Article

Isolation and characterization of nanofibers from agricultural residues-Wheat straw and soy hulls

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Abstract

Cellulose nanofibers were extracted from the agricultural residues, wheat straw and soy hulls, by a chemi-mechanical technique to examine their potential for use as reinforcement fibers in biocomposite applications. The structure of the cellulose nanofibers was investigated by transmission electron microscopy. The wheat straw nanofibers were determined to have diameters in the range of 10-80 nm and lengths of a few thousand nanometers. By comparison, the soy hull nanofibers had diameter 20-120 nm and shorter lengths than the wheat straw nanofibers. Chemical characterization of the wheat straw nanofibers confirmed that the cellulose content was increased from 43% to 84% by an applied alkali and acid treatment. FT-IR spectroscopic analysis of both fibers demonstrated that this chemical treatment also led to partial removal of hemicelluloses and lignin from the structure of the fibers. PXRD results revealed that this resulted in improved crystallinity of the fibers. After mechanical treatments of cryocrushing, disintegration and defibrillation, the thermal properties of the nanofibers were studied by the TGA technique and found to increase dramatically. The degradation temperature of both nanofiber types reached beyond 290 degrees C. This value is reasonably promising for the use of these nanofibers in reinforced-polymer manufacturing.

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... As with banana fiber, the aliphatic saturated C-H stretching vibration in cellulose and hemicellulose fibers causes the peaks at 2917 cm −1 [32][33][34][35]. The peak of 1731 cm −1 is formed by the ester linkage of acetyl hemicellulose and uronic ester groups or the ester linkage of lignin's carboxylic frulic groups and p-coumaric acids [32][33][34][35][36]. The reect C-H asymmetric deformation is responsible for the peak of 1370 cm −1 [32,35,37]. ...
... The reect C-H asymmetric deformation is responsible for the peak of 1370 cm −1 [32,35,37]. The peaks of 1509 cm −1 and 1425 cm −1 are produced by the aromatic C=C stretch of lignin aromatic rings [35,36,38]. The C-O stretch and deformation bands in cellulose, lignin, and residual hemicellulose range from 1200 to 1056 cm −1 [32,34,35,39]. ...
... The peak of 1033 cm −1 in hemicelluloses is caused by C-O, C-C stretching, or C-OH bending [40,41]. the peak of 903 cm −1 owing to the β-glycosidic connections of the cellulose glucose ring [36,38,41]. Analysis of the FTIR results for plaster is shown in Figure 7b, The stretching vibration bands of O-H characterize the two bands at 3605 and 3555 cm −1 , respectively [42,43]. ...
Article
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In this paper, a new material consisting of plaster and wheat straw was studied with the purpose of reducing energy consumption. The aim of this study is to test this new compound for use as an insulation material in buildings, where the samples were prepared by mixing wheat straw after grinding it in different proportions from 0% to 15%. On the other hand, the physico-chemical properties and thermal conductivity of the samples were experimentally investigated, and the time lag and energy savings for the samples were also studied. The results showed that the addition of wheat straw leads to an increase in the time lag and also to a decrease in the thermal conductivity, which leads to an improvement in the thermal resistance and energy savings. As well, fiber addition has no effect on the chemical composition of the matrix, as shown by FTIR and XRD analyses.The findings of the DSC and TGA analysis indicate that the inclusion of wheat straw fibers has an effect on the thermal characteristics of the matrix. This new biocomposite can be used as an additive to plaster to create environmentally friendly composite materials for thermal insulation in buildings.
... 4890 due to stretching vibration of O-H from OH groups of cellulose molecules (Khalil et al. 2001;Xu et al. 2005;Sain et al. 2006;Viera et al. 2007;Mandal and Chakrabarty 2011;Li et al. 2012;Lu and Hsieh 2012;Hokkanen et al. 2013;Rosli et al. 2013;Maiti et al. 2013;Kumar et al. 2014;Maryana et al. 2014;Li et al. 2014;Almasian et al. 2016;Saelee et al. 2016;Wulandari et al. 2016;Lam et al. 2017). The peak from 1649 to 1641 cm -1 was also related to the O-H vibration of the adsorbed water (Ramo et al. 2000;Alemdar and Sain 2008;Mandal and Chakrabarty 2011;Li et al. 2012;Hokkanen et al. 2013;Almasian et al. 2016;Wulandari et al. 2016). Moreover, one peak at 894 cm -1 is related to the glycosidic CH deformation with a ring vibration contribution and O-H bending, which are known characteristics of b-glycoside linkages between the anhydro glucose units in cellulose. ...
... The peak observed at 894 cm -1 in the bleached soda bagasse pulp sample is related to β-glycoside bonds in cellulose (Nelson and O'Connor 1964;Alemdar and Sain 2008;Mandal and Chakrabarty 2011;Wulandari et al. 2016). With increasing hydrolysis time, peak intensity was decreased at 894 cm -1 , indicating that the glycosidic bond was broken and more OH groups were released (Niua et al. 2017). ...
... Nelson and O'Connor 1964;Alemdar and Sain 2008;Mandal and Chakrabarty 2011; Li et al. 2014;Wulandari et al. 2016; Lam et al. 2017). The peaks from 1505 to 1511 and 1602 to 1604 cm -1 are attributed to C=C stretching vibration in lignin(Kumar et al. 2014), and the band at 1245 cm -1 is related to C-O stretching vibration of aryl group in lignin(Mandal and Chakrabarty 2011;Rosli et al. 2013;Saelee et al. 2016). ...
Article
Cellulose nanocrystals (CNC) and succinic anhydride-modified CNC from bleached soda bagasse pulp under different parameters were used to remove Cd+2 and Pb+2 heavy metal ions from aqueous solution. The aim was to modify the chemical structure of cellulose nanocrystal using succinic anhydride and to investigate the effect of CNC and succinic anhydride-modified CNC on the adsorption capacity of heavy metal ions. The adsorption parameters included pH (3, 5, 6, and 8), contact time (30, 60, and 90 min), and initial metal ion concentration (40, 120, 200, and 280 ppm). It was found at all pHs that the adsorption capacity of the succinic anhydride-modified CNC adsorbent was much higher than that of the default CNC adsorbent, and this difference was greater at higher pHs. The results showed that the maximum metal ion adsorption was obtained at pH 6 for Pb+2 and Cd+2 ions. Both types of CNC had a higher adsorption capacity for lead ions than cadmium ions. To investigate the kinetic models of adsorption, the pseudo-first-order and pseudo-second-order kinetics model were used. Adsorption on unmodified adsorbent gave a better fit to the Langmuir model than the Freundlich model for both Pb+2 and Cd+2 metals. In addition, the adsorption mechanism was changed by modifying the adsorbent, and then it had better fit to the Freundlich adsorption model. Adsorption of cadmium and lead metals by adsorbents fit better to the pseudo-first-order kinetics model.
... Dandia et al. [53] found that 70 • C was optimal for maximum conversion to the rGO/CuO product. Also, it can be seen that as temperature increased, the I c of rGO increased and that of CuO decreased, for both methods A and B. This was in agreement with Pratheepa and Lawrence [56], who concluded that rGO% increase significantly enhanced the yield of the photocatalytic reduction of CO 2 to methanol, while Rashidian et al. [47] found that the I c of rGO was 86.2%. Dutta et al. [54] showed that CuO content increment had no obvious influence on I c , and Sahu et al. [55] concluded that with temperature increment, CuO I c % decreased due to particle coalescence, as a result of which there was a decrease in the average crystallite size and I c . ...
... The I c % of CuO (A) values were found to be highest, followed by rGO/CuO (A) and rGO (A) respectively, as explored in Section 3.3. When the test period increased, I c values decreased from 85.88% to 75.68% and 71.28% to 62.81% for rGO/CuO methods A and B, respectively, in agreement with [51][52][53][54][55][56][57][58][59][60][61][62][63][64], which proves that the temperature effect had a higher effect compared with the test time period, in agreement with [58][59][60][61][62]. Kargarzadeh et al. [65] and Kian et al. [66] proved that increasing the test time beyond 30 min decreased the crystallinity index values, among which the best values were achieved at 40 min at 45 • C and 65% sulfuric acid [63]. However, Al-Dulaimi et al. [67] found that the best crystallinity index values using hydrolysis reaction were achieved at 80 min with 58% sulfuric acid. ...
... The number of particles in the rGO/CuO composites and their size distribution are shown in Figure 5 (53,(55)(56). Sumedh et al. [4] found that CuO has an average size of 15-27 nm whereas rGO size varies from 15 to 80 nm for rGO/CuO composites, and Mahjouri et al. [68] showed that DLS analysis of rGO-CuO composites produces average size ranges from 43 to 86 nm. Hassan et al. [69] showed that 90% of CuNPs were less than 85.45 nm in size, and Yu et al. [70] found that the CuNP sizes ranged from 15 to 165 nm. ...
Article
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In this study, we synthesized a reduced form of graphene oxide/copper oxide (rGO/CuO) nanocompounds produced at rGO wt. of 0.125%, 0.25%, 0.5% and 1%. The crystallinity indexes for rGO and rGO/CuO increased, and that for CuO decreased as the test temperatures increases, while the crystallinity indexes of rGO, CuO and rGO/CuO decreases with test periods increment. Measurement by dynamic light scattering reported average crystallite sizes of 0.7, 8.8, 25.4, 38.5 nm for 0.125 wt.% rGO/CuO, 0.25 wt.% rGO/CuO, 0.50 wt.% rGO/CuO and 1.0 wt.% rGO/CuO respectively. The electrochemical properties of the nanocomposites were checked. The rGO/CuO XRD peaks were 18.114320 Å, 225.1856 Å, 321.41740 Å, and 365.98290 Å, with 11.051640%, 0.461075%, 0.280083%, and 0.174259% for 2ϴ of 22.2031°, 43.5865°, 50.7050°, and 74.3729°, respectively. FTIR spectroscopy identified the existence of vibrational frequencies with pseudo-capacitance at 458 cm−1 which confirmed the presence of rGO-CuO nanoparticles. The voltammetry of rGO-CuO indicated the increment of electrochemical activity, large capacitance, and conduction in the reduced rGO/CuO composite. For rGO wt. of 0.125%, 0.25%, 0.5%, and 1.0%, the rGO/CuO composite specific capacitance was 561 F/g, 582 F/g, 597 F/g, and 611 F/g, respectively, which indicated good electrochemical performance.
... The discrete peak at 1740 cm −1 is ascribed to uronic ester and/or acetyl groups of hemicelluloses, or the carboxylic group of ferulic and p-coumaric acids from lignin or hemicellulose. Less stretching obtained in this region for RLCs indicates the removal of some of these mentioned groups during the washing process [5,37,38]. The peak at 1511 cm −1 corresponds to the aromatic ...
... The discrete peak at 1740 cm −1 is ascribed to uronic ester and/or acetyl groups of hemicelluloses, or the carboxylic group of ferulic and p-coumaric acids from lignin or hemicellulose. Less stretching obtained in this region for RLCs indicates the removal of some of these mentioned groups during the washing process [5,37,38]. The peak at 1511 cm −1 corresponds to the aromatic ring of lignin's C=C stretching vibration, whereas the C-H asymmetric distortions are seen at 1379 cm −1 , and C-O stretching is visible in the 950-1200 cm −1 area [5]. ...
Article
Regenerated lignocellulose nanofibrils (RLCNFs) have recently piqued the interest of researchers due to their widespread availability and ease of extraction. After dewaxing, we treated sisal fiber with alkali, followed by heating and agitation, to obtain RLCNFs, which were then vacuum oven-dried. We used a variety of characterization techniques, including XRD, SEM, and FT-IR, to assess the effects of the alkali treatment on the sisal fiber. Various characterizations demonstrate that lignocellulose fibrils have been successfully regenerated and contaminants have been removed. In addition, employing the RLCNFs as a stabilizer, stable Pickering emulsions were created. The effects of RLCNF concentration in the aqueous phase and water-to-oil volume ratio on stability were studied. The RLCNFs that have been produced show promise as a stabilizer in Pickering emulsions.
... The band at 1427 cm −1 might be attributed to the symmetric bending of CH2, while the band at 1318 cm −1 corresponds to O-H in-plane bending. The absorbance band observed around 1161 cm −1 was assigned to C-O-C asymmetric stretching vibrations, and the absorption band at 1029 cm −1 was associated with the stretching vibration of the primary hydroxyl group [56]. The obtained spectra also showed a band around 899 cm −1 , corresponding to interactions between glycosidic linkages and glucose units of the cellulose [57]. ...
... The band at 1427 cm −1 might be attributed to the symmetric bending of CH 2 , while the band at 1318 cm −1 corresponds to O-H in-plane bending. The absorbance band observed around 1161 cm −1 was assigned to C-O-C asymmetric stretching vibrations, and the absorption band at 1029 cm −1 was associated with the stretching vibration of the primary hydroxyl group [56]. The obtained spectra also showed a band around 899 cm −1 , corresponding to interactions between glycosidic linkages and glucose units of the cellulose [57]. ...
Article
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In this study, thin chitosan-gelatin biofilms cross-linked with dialdehyde cellulose nanocrystals for dressing materials were received. Two types of dialdehyde cellulose nanocrystals from fiber (DNCL) and microcrystalline cellulose (DAMC) were obtained by periodate oxidation. An ATR-FTIR analysis confirmed the selective oxidation of cellulose nanocrystals with the creation of a carbonyl group at 1724 cm−1. A higher degree of cross-linking was obtained in chitosan-gelatin biofilms with DNCL than with DAMC. An increasing amount of added cross-linkers resulted in a decrease in the apparent density value. The chitosan-gelatin biofilms cross-linked with DNCL exhibited a higher value of roughness parameters and antioxidant activity compared with materials cross-linked with DAMC. The cross-linking process improved the oxygen permeability and anti-inflammatory properties of both measurement series. Two samples cross-linked with DNCL achieved an ideal water vapor transition rate for wound dressings, CS-Gel with 10% and 15% addition of DNCL—8.60 and 9.60 mg/cm2/h, respectively. The swelling ability and interaction with human serum albumin (HSA) were improved for biofilms cross-linked with DAMC and DNCL. Significantly, the films cross-linked with DAMC were characterized by lower toxicity. These results confirmed that chitosan-gelatin biofilms cross-linked with DNCL and DAMC had improved properties for possible use in wound dressings.
... After each chemical treatment, these peaks become sharp, and this situation indicates an increase in cellulose content [45]. The presence of a significant peak at about 1740 cm −1 is due to the C = O stretching of acetic and uronic ester groups of hemicellulose or ester linkage of the carboxylic groups of ferulic and p-coumaric acids of lignin [5,79,80]. This peak was gradually removed as it moved from raw to bleached fiber of the Ensete ventricosum pseudo-stem and finally disappeared completely from the final product, CNCs. ...
... This peak was gradually removed as it moved from raw to bleached fiber of the Ensete ventricosum pseudo-stem and finally disappeared completely from the final product, CNCs. Chemo pretreatments caused the disappearance of hemicellulose and lignin [5,79]. 1634.74 cm −1 represents OH bending of adsorbed water (Hemmati et al., 2018a), whereas 1414.16 and 1327.74 ...
Article
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Ensete ventricosum (false banana) is a common food source for a considerable section of Ethiopia’s population in the central, southern, and southwestern areas. Ensete ventricosum pseudo-stem fiber is a type of agro-industrial waste that is widely available across the country. It has a limited number of known conventional applications and merits further investigations. One of the activities that prompted the completion of this study was the upgrading of Ensete ventricosum pseudo-stem fiber to value-added products such as cellulose nanocrystals. The goal of this study was to extract cellulose nanocrystals from Ensete ventricosum pseudo-stem fiber using sulfuric acid hydrolysis. An acid-catalyzed reaction technique using 1:20 mL cellulose to H2SO4 (51.1%) ratio and hydrolysis period of 52 min at 51 °C reaction conditions was used to separate cellulose nanocrystals from Ensete ventricosum pseudo-stem fiber cellulose. Thermal stability, crystallinity, surface charge, shape, size, and functional changes were all assessed in the cellulose nanocrystals that resulted. It had a better crystallinity index (78.0%), an average particle size of 66.7 nm, a yield of 39.78%, good thermal stability (> 300 °C), and a morphologically comparable rod-shaped structure. As a result, it is feasible to conclude that Ensete ventricosum pseudo-stem fiber offers a lot of potential for isolating cellulose nanocrystals for various applications.
... The world production of soybean (2020/2021 crop) is estimated at 362,947 million tons and that of Brazil at 135,409 million tons [36], with each ton of soy yielding around 20 kg of hulls (2%) [37]. Soy hulls are generally used in animal feed, however, a significant amount of this residue is not used [38]. ...
... It has been found [38] that the addition of CWs obtained from soybean hulls significantly increases the mechanical strength of a rubber matrix. This effect is attributed to the high aspect ratio and the stiffness of the percolating nanoparticles network formed within the polymer matrix. ...
Article
Zn-soybean nanocrystal composite coating was produced through electrodeposition. The coatings were obtained in the absence and presence of different concentrations of soybean nanocrystals obtained through the bleaching process with a sodium hypochlorite (NaClO) solution and hydrolysis in a sulfuric acid solution. The effect of nanocrystal addition on the coating characteristics was analyzed through scanning electron microscopy (SEM), roughness measurements, hardness measurements, corrosion resistance evaluation and current efficiency determination. Corrosion resistance was evaluated at 0.5 wt% NaCl solution through mass loss and electrochemical measurements. The results obtained indicate that the presence of soybean nanocrystal reduces the hardness, but increases the corrosion resistance of the Zn coating and this effect is related to the decrease in the roughness of the coating.
... However, the CNF XRD pattern did not show the third peak that appeared on the WSC XRD pattern at 31.2° (Figure 7b), which represented the crystal plane (300) in Cellulose I. The calculated CNF crystallinity was 57.5%, which was higher than the wheat straw crystallinity (42.2%), and also significantly higher than that reported by Alemdar [42]. ...
... However, the CNF XRD pattern did not show the third peak that appeared on the WSC XRD pattern at 31.2 • (Figure 7b), which represented the crystal plane (300) in Cellulose I. The calculated CNF crystallinity was 57.5%, which was higher than the wheat straw crystallinity (42.2%), and also significantly higher than that reported by Alemdar [42]. ...
Article
To accelerate the high value-added usage of agricultural residue, cellulose and cellulose nanofibers (CNFs) were extracted from wheat straw and then formed into all-cellulose nanocomposite films. The acid-alkali method (AM) and the extraction method (EM) were respectively adopted to prepare wheat straw cellulose (WSC), and the TEMPO oxidation method was used to extract CNFs. The nanocomposite films were fabricated by dissolving WSC and adding different CNF contents of 0.0, 0.5, 1.5, and 3.0%. There was a better miscibility for the all-cellulose nanocomposite film prepared by EM (Composite-E) compared to that for the all-cellulose nanocomposite film prepared by AM (Composite-A). Composite-E also showed a better optical transparency than Composite-A. The thermal stability of the two RWSCs presented contrary results when the CNFs were added, indicating a higher thermal stability for Composite-E than for Composite-A. This should have determined the properties of the films in which Cellulose I and Cellulose II coexisted for the all-cellulose nanocomposite films, and the forming mechanism of Cellulose II and crystallinity were determined by the cellulose-extracting method. X-ray diffraction (XRD) and Fourier-transform infrared (FT-IR) spectroscopy also showed that there was more Cellulose I in Composite-E than in Composite-A. The results are expected to enrich the data for deep processing of agricultural residues.
... The discrete peak at 1740 cm −1 is ascribed to uronic ester and/or acetyl groups of hemicelluloses, or the carboxylic group of ferulic and p-coumaric acids from lignin or hemicellulose. Less stretching obtained in this region for RLCs indicates the removal of some of these mentioned groups during the washing process [5,37,38]. The peak at 1511 cm −1 corresponds to the aromatic ...
... The discrete peak at 1740 cm −1 is ascribed to uronic ester and/or acetyl groups of hemicelluloses, or the carboxylic group of ferulic and p-coumaric acids from lignin or hemicellulose. Less stretching obtained in this region for RLCs indicates the removal of some of these mentioned groups during the washing process [5,37,38]. The peak at 1511 cm −1 corresponds to the aromatic ring of lignin's C=C stretching vibration, whereas the C-H asymmetric distortions are seen at 1379 cm −1 , and C-O stretching is visible in the 950-1200 cm −1 area [5]. ...
Article
Full-text available
Regenerated lignocellulose nanofibrils (RLCNFs) have recently piqued the interest of researchers due to their widespread availability and ease of extraction. After dewaxing, we treated sisal fiber with alkali, followed by heating and agitation, to obtain RLCNFs, which were then vacuum oven-dried. We used a variety of characterization techniques, including XRD, SEM, and FT-IR, to assess the effects of the alkali treatment on the sisal fiber. Various characterizations demonstrate that lignocellulose fibrils have been successfully regenerated and contaminants have been removed. In addition, employing the RLCNFs as a stabilizer, stable Pickering emulsions were created. The effects of RLCNF concentration in the aqueous phase and water-to-oil volume ratio on stability were studied. The RLCNFs that have been produced show promise as a stabilizer in Pickering emulsions.
... The dominant peaks in the range of 3400-2800 cm −1 were due to the stretching vibration of CH and OH. The prominent peak at 1720 cm −1 in Yucca leaves was due to the C = O stretching in 125 hemicellulose and/or lignin and disappeared after alkali treatment (Alemdar and Sain 2008). The disappearance of this peak could be attributed to the cleavage of the ester-bond component of hemicellulose by alkali and oxidative treatment (Sheltami et al. 2012). ...
... The peaks in the range of 1200-900 cm −1 could be attributed to C-O stretching 135 (Xiao, Sun, and Sun 2001). The peaks at 1097 cm −1 and 896 cm −1 , which were related to the C-O stretching and C-H rocking vibrations of cellulose, were increased after alkali treatment (Alemdar and Sain 2008;Xiao, Sun, and Sun 2001). The ring bend and CH out of the plane of lignin located in the 660-800 cm −1 region was observed in the Yucca leaf spectra; then it disappeared after alkali treatment. ...
Article
The present study addressed the isolation of cellulose microfibers (CMF) from Yucca leaves using chemical treatments. This study was conducted in three stages, namely, two stages of alkaline treatments (NaOH 3%), and a single stage of bleaching treatment (H2O2 6%). The resulting microfibers were characterized using Scanning Electron Microscope (SEM), X-Ray diffraction (XRD), Fourier Transform Infra-red (FTIR), and Thermogravimetric Analysis (TGA). Alkaline and oxidative bleaching treatments had a positive impact on defibrillation and morphology of the fibers by the partial removal of non-cellulosic materials. FTIR results also revealed that most of the amorphous components were removed through proper alkali and bleaching treatments from the fibers. Further, SEM analysis showed that cellulose microfibers with an average diameter of 7 µm were successfully isolated with a yield of about 25%. The crystallinity index (76%) and crystallite size (3.41 nm) of CMF were also determined through the XRD analysis. The method used in this study led to the isolation of the microfibers with the thermal stability of 215°C and activation energy of 67.72 kJ/mol. The values obtained in this study were reasonably promising for the use of Yucca cellulose microfibers in various applications, such as reinforced-polymer manufacturing.
... The discrete peak at 1740 cm −1 is ascribed to uronic ester and/or acetyl groups of hemicelluloses, or the carboxylic group of ferulic and p-coumaric acids from lignin or hemicellulose. Less stretching obtained in this region for RLCs indicates the removal of some of these mentioned groups during the washing process [5,37,38]. The peak at 1511 cm −1 corresponds to the aromatic ...
... The discrete peak at 1740 cm −1 is ascribed to uronic ester and/or acetyl groups of hemicelluloses, or the carboxylic group of ferulic and p-coumaric acids from lignin or hemicellulose. Less stretching obtained in this region for RLCs indicates the removal of some of these mentioned groups during the washing process [5,37,38]. The peak at 1511 cm −1 corresponds to the aromatic ring of lignin's C=C stretching vibration, whereas the C-H asymmetric distortions are seen at 1379 cm −1 , and C-O stretching is visible in the 950-1200 cm −1 area [5]. ...
Article
Full-text available
Regenerated lignocellulose nanofibrils (RLCNFs) have recently piqued the interest of researchers due to their widespread availability and ease of extraction. After dewaxing, we treated sisal fiber with alkali, followed by heating and agitation, to obtain RLCNFs, which were then vacuum oven-dried. We used a variety of characterization techniques, including XRD, SEM, and FT-IR, to assess the effects of the alkali treatment on the sisal fiber. Various characterizations demonstrate that lignocellulose fibrils have been successfully regenerated and contaminants have been removed. In addition, employing the RLCNFs as a stabilizer, stable Pickering emulsions were created. The effects of RLCNF concentration in the aqueous phase and water-to-oil volume ratio on stability were studied. The RLCNFs that have been produced show promise as a stabilizer in Pickering emulsions.
... Interestingly, our thermal compression technique, which further induced the z-shrinkage, improved the strength, modulus, and toughness by 12%, 11%, and 34% than the non-compressed films, i.e., xy and z films. This simultaneous improvement of strength and toughness was possible 83 As previous reports 29,36 suggest that the mechanical properties of CNF films are a function of density, we normalized the tensile strength, strain, modulus, and toughness by density and ran the statistical analysis again. The results of analysis of variance before and after density normalization are shown in Table C.2 and Table C ...
... homogenization, refining, grinding). Alternative non-woody sources like bast fibers 81 , fruit stalks 82 and agricultural residues of different crops83,84 are also studied as inexpensive sources. However, all those sources are not still commercially available on a large scale and require chemical and mechanical pretreatment even before nanofibrillation increasing the ultimate cost of CNF production. ...
Thesis
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Self-standing cellulose nanofibril (CNF) films are regarded as one of the promising alternatives to current petroleum-based packaging materials. The mechanical and barrier properties of CNF films are not yet up to the mark for certain applications, especially at high relative humidity. Those properties of CNF films can be tuned by the drying methods of films, degree of fibrillation, cross-linking, and controlled shrinkage. A comprehensive understanding of these processes and their influence on the structure and properties of CNF films have been presented in this thesis. First, we prepared CNF films from CNF suspensions with two different degrees of fibrillation- standard CNF (90% fine) and high-fine CNF (97% fine) by casting and filtration. These were dried in four different ways: air, oven, heat gun, and hot press drying. The CNF films made by hot press drying showed the highest tensile strength (98.82 MPa) and lowest water vapor permeability (13.91 g.mm/m2.day.kPa). A facile thermal compression on the dried films further improved the strength by 13.1%, reduced the water vapor permeability by 22% and oxygen permeability by 43%. With the hot-press drying and thermal compression technique, we created self-standing films of lignin-containing cellulose nanofibrils (LCNFs) derived from recycled old corrugated cardboard (OCC) pulp that cost considerably less than bleached softwood Kraft (BSK) pulp yet only use half as much energy for refining to obtain the same fines content. The low zeta potential (-3.83 mV) of OCC-derived LCNFs (OCC-LCNFs) resulted in aggregation of the fibrils in aqueous suspension, leading to considerable unpredictability in oxygen permeability values (coefficient of variation 36%). The addition of 3 wt.% (based on the dry weight of LCNF) carboxymethyl cellulose (CMC) lowered the coefficient of variation with an average oxygen permeability of 1478 (cc.µm/m2.atm.day) at 80% relative humidity. We demonstrated that ionic crosslinking with Al3+ or covalent crosslinking with polyamide epichlorohydrin could decrease the oxygen permeability by 30% at 23 °C and 80% relative humidity, while also significantly enhancing the tensile strength and modulus. Finally, the shrinkage in CNF films upon drying has been studied. The shrinkage was classified into radial and vertical direction. Two types of CNF films were prepared: one in a restrained condition that did not allow shrinkage in the radial direction but enabled it in the vertical direction and another one with 11% radial shrinkage but limited vertical shrinkage. The radial shrinkage led to a more porous and less dense structure than the vertical shrinkage, which brought about poorer oxygen and moisture barrier performance than its counterpart. Interestingly, radial shrinkage resulted in 140% and 90% higher strain at break and toughness in films with a significant sacrifice in strength and modulus. The structural changes caused by the radial and vertical shrinkage were revealed by scanning electron and optical microscope images.
... Cellulose shows orderly hydrogen bonding arrangement among the molecules, and hence during acid hydrolysis, acid could not penetrate and hydrolyze the crystalline region. Therefore, it cleaved only the amorphous region, leaving the crystalline area intact, which resulted in high degree of crystallinity of CNC [18,19]. PEG was observed to show major XRD peaks at 2 theta = 19.39°, ...
... Cellulose shows orderly hydrogen bonding arrangement among the molecules, and hence during acid hydrolysis, acid could not penetrate and hydrolyze the crystalline region. Therefore, it cleaved only the amorphous region, leaving the crystalline area intact, which resulted in high degree of crystallinity of CNC [18,19]. PEG was observed to show major XRD peaks at 2 theta = 19.39 ...
Article
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A Semi Interpenetrating Polymer Network (semi-IPN) hydrogel was prepared and loaded with an antibiotic drug, gentamicin, to investigate the wound healing activity of this system. The semi-IPN hydrogel was synthesized by combining natural polymer cellulose nanocrystal (CNC) and synthetic polymer polyethylene glycol (PEG) and poly (N,N′-dimethyl acrylamide) (PDMAA), which was initially added as a monomer dimethyl acrylamide (DMAA). CNC was prepared from locally obtained jute fibers, dispersed in a PEG-NaOH solvent system and then mixed with monomer DMAA, where polymerization was initiated by an initiator potassium persulphate (KPS) and cross-linked by N,N′-methylenebisacrylamide (NMBA). The size, morphology, biocompatibility, antimicrobial activity, thermal and swelling properties of the hydrogel were investigated by different characterization techniques. The biocompatibility of the hydrogel was confirmed by cytotoxicity analysis, which showed >95% survival of the BHK-21, Vero cell line. The drug loaded hydrogel showed antimicrobial property by forming 25 and 23 mm zone of inhibition against Staphylococcus aureus (gram-positive) and Escherichia coli (gram-negative) bacteria, respectively, in antimicrobial analysis. At pH 5.5, 76% of the drug was released from the hydrogel within 72 h, as observed in an in vitro drug release profile. In an in vivo test, the healing efficiency of the drug loaded hydrogel was examined on a mice model with dorsal wounds. Complete healing of the wound without any scar formation was achieved in 12 days, which revealed excellent wound healing properties of the prepared drug loaded semi-IPN hydrogel. These results showed the relevance of such a system in the rapid healing of acute wounds.
... All these mentioned bands have disappeared in the FTIR spectra of NFC and CNC, meaning the successful removal of non-cellulosic material upon the treatments. The main absorption peak located near 3,424 cm −1 in the spectrum is formed by the free O-H stretching vibrations of the OH groups in the cellulose molecule (Alemdar and Sain 2008;Johnson et al., 2011). Moreover, the absorption peaks at 2,918 cm −1 , 1,639 cm −1, and 1,424 cm −1 are attributed to the characteristic C-H stretching vibration, the O-H bending of the adsorbed water, and the CH 2 bending vibration of the crystalline region in cellulose (Mandal and Chakrabarty 2011;Wang et al., 2017). ...
Article
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Nanocellulose has gained increasing interest due to its excellent properties and great potential as a functional component or carrier in food and pharmaceutical industries. This study investigated the structural, thermal, and physicochemical properties of nanofibrillated cellulose (NFC) and nanocrystalline cellulose (CNC) extracted from bamboo shoot (Leleba oldhami Nakal) processing byproducts. NFCs were prepared through low concentration acid hydrolysis combined with ultrasonic treatment. CNCs were further isolated from NFCs using sulfuric acid hydrolysis treatment. TEM images showed that NFC and CNC exhibited typical long-chain and needle-like structures, respectively. CNC suspension was stable due to its zeta potential of -34.3 ± 1.23 mV. As expected, both NFC and CNC displayed high crystallinity indexes of 68.51 and 78.87%, and FTIR analysis confirmed the successful removal of lignin and hemicellulose during the treatments. However, the thermogravimetric analysis indicated that sulfuric acid hydrolysis decreased the thermal stability of CNCs. The improved physicochemical properties of NFC and CNC suggested their potential in various applications.
... Including hydrogen bonds, 2898 cm -1 due to CH and CH2 stretching; 1650 cm -1 corresponding to OH from absorbed water; and 1061 cm -1 due to C-O/C-C stretching [44][45]. Figure 1A revealed the presence of a peak around 1505cm -1 of the aromatic C=C stretch of lignin [46]. The intensity of the band decreased in the spectra of the peroxidated cellulose fibers in Figure 1B. ...
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The performance of peroxidated powdered fibers of corn stover and sugarcane bagasse as fillers in natural rubber was evaluated in this study. Powdered corn stover and sugar bagasse fibers were subjected to the conventional peroxidation treatment for conversion to more hydrophobic fillers with enhanced tensile properties. The physicochemical properties of the peroxidated fibers were assessed using standard methods. Morphological properties, thermal stability, and functional groups were also assessed. The treated and untreated fibers were then used as fillers in natural rubber compounding using the two-roll mill, compression moulding and subjected to physico-mechanical characterization. There was improved dispersion of the peroxidated fibers in the polymer matrix, which meant significant improvement in the reinforcement and mechanical properties of the natural rubber compounds. A morphological study of the composites showed that natural rubber-peroxided fiber composites have very good dispersion in the rubber matrix. The mechanical properties showed that the composites have improved properties with the highest tensile strength of 44.55 MPa, modulus at 100% elongation of 6.11 MPa, elongation at break of 294%, hardness of 74.30 IRHD. INTRODUCTION In recent decades, natural fibres have been considered as alternative bio-filler as reinforcing agents to synthetic fibres for composite applications because of their renewability, biodegradability, sustainability, good availability, low cost, low density, low abrasiveness, high specific stiffness, and strength [1-3] However, natural fibres also have some difficulties as their flammability, low thermal stability, and sensitivity to polar characters lead to poor interaction with hydrophobic polymer matrices. Thus, the pretreatment of natural fibres is necessary to enhance their dispersion in the polymer matrix and improve the mechanical performance of the polymer composites.
... The finding was almost similar to that reported by Ribeiro et al. [56] in untreated mandarin peels, where the peak was located around~1750 cm −1 . The p-coumeric acids of lignin and/or hemicellulosic acids were also linked to this peak [57]. Peak 1602 cm −1 appeared to represent the stretching vibration of carboxyl ions (COO-) which indicated the presence of pectin in HPP powder [10]. ...
... The diffraction spectra of all samples were similar, demonstrating that the form of the raw material did not affect the chemical functionality of the isolated CN. A dominant band of 3450-3400 cm −1 and 2900 cm −1 contributed to the O-H and C-H stretching vibrations, corresponding to the aliphatic moieties in polysaccharides in all spectra [29]. Another spectrum observed at the wavenumber of 1640 cm −1 is related to the bending behavior of the O=H groups, affected by the absorption of water. ...
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Cellulose nanospheres (CN) have been considered a leading type of nanomaterial that can be applied as a strengthening material in the production of nanocomposites. This work aimed to isolate and characterize the properties of CN from different agricultural by-products. CNs were successfully isolated from rice straw, corncob, Phulae pineapple leaf and peel using acid hydrolysis (60% H2SO4) combined with homogenization-sonication (homogenized at 12,000 rpm for 6 min and ultrasonicated for 10 min). The results showed that the CN from rice straw (RS-CN) and corncob (CC-CN) exhibited high yields (22.27 and 22.36%) (p < 0.05). All hydrolyzed CNs exhibited a spherical shape with a diameter range of 2 to 127 nm. After acid hydrolysis, Fourier transform infrared (FTIR) results showed no impurities. X-ray diffraction (XRD) showed that the structure of cellulose was changed from cellulose-I to cellulose-II. However, cellulose-I remained in pineapple peel cellulose nanosphere (PP-CN). The crystalline index (CI) ranged from 43.98 to 73.58%, with the highest CI obtained in the CC-CN. The CN from all sources presented excellent thermal stability (above 300 °C). The functional properties, including water absorption Index (WAI), water solubility index (WSI) and swelling capacity were investigated. PP-CN showed the highest WAI and swelling capacity, while the PL-CN had the highest WSI (p < 0.05). Among all samples, CC-CN showed the highest extraction yield, small particle size, high CI, and desirable functional properties to be used as a material for bio-nanocomposites film.
... Consequently, it is of major concern to grow economic and scientific methods for recovering cellulose from agricultural wastes. Lots of efforts have been made by various researchers and engineers to produce environmental-friendly composite constituents from agricultural wastes [8], [9], [10], [11], [12]. ...
Article
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The environmental concern occurs due to the extreme use of synthetic materials that have been fortified to develop innovative, multifunctional, and sustainable materials using copious lignocellulosic biomass. In this present study, work was done on the extraction of nanocellulose from wheat straw, and found that wheat straw is an admirable source of cellulose. Chemical processes were used to isolate the cellulose and remove unwanted lignin and hemicellulose from wheat straw followed by sonication, cryo-crushing, and magnetic stirring to achieve nanocellulose. The observed amount of cellulose (36.1%), hemicellulose (30.3%), lignin (17%), and ash content (9.2%) of raw wheat straw. Structural, morphological, and thermal characterization were estimated from FTIR, XRD, FESEM, TEM, DSC, TGA, and AFM for the identification and characterization of extracted cellulose from wheat straw. FTIR showed that the peaks at wavelength 1430.50 cm-1 and 1638.41 cm-1 both show that cellulose is present in the extracted nanocellulose. Extracted nanocellulose was crystalline and had a 68.96% Crystallinity Index. Morphological analysis, FESEM showed that the untreated wheat straw has an irregular porous structure but the extracted nanocellulose has a regular shape having straight fibers connected. TEM analysis showed that the extracted nanocellulose has a spherical shape structure connected, showing the regular shape, the obtained spherical shape regulates the nanocellulose for further applications. Thermal degradation was observed using TGA which shows that the nanocellulose decomposition was observed around 3600C. AFM determination shows a bell-shaped structure on a smooth surface with a particle height of 3.2 nm and the mean roughness of 110.4 nm was obtained from the extracted nanocellulose. Extracted nanocellulose has a particle size of 58.77 nm.
... Among these commercial fillers, carbon black is the most commonly used filler and the high cost of this petroleum-based material together with the quest for a sustainable environment has led to a search for low-cost and renewable material as fillers in the rubber processing industry. Recently, there has been a growing interest in the use of organic fillers, especially agricultural and industrial wastes, such as rice husk ash [7][8][9][10][11][12][13], almond shell [12], corn derivatives [14], coconut fiber [15][16][17][18][19], palm kernel husk [20], oil palm ash [21][22][23][24], eggshell powder [23][24][25][26][27][28], oil palm fiber [26], tomato peel [27], soy hulls [29][30][31], cocoa pod husk [32], neem seed [33], cereal straw [34] etc. as reinforcing agents in natural rubber processing due to their low cost and environmental friendliness. Among these ecofriendly fillers, the use of natural fibers derived from plants as flax, hemp, and cotton; animals as silk and wool, is receiving enormous attention from researchers due to their low cost, sustainability, high aspect ratio, recyclability, biodegradability, and natural abundance. ...
Article
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The mechanical properties of materials such as natural rubber composites determine their usefulness as engineering or biological materials. The thermodynamic properties of natural rubber composites filled with clay and corn cob at varying volume fraction of filler were studied with a view of relating and comparing thermodynamic parameters (ΔG, ΔH and ΔS) to mechanical properties (Young’s modulus, tensile strength, elongation at break, etc) of natural rubber composites. The rubber composites were prepared using a standard compounding recipe. The tension observed for each rubber composite as a result of changes in temperature was used in evaluating thermodynamic parameters via Arrhenius equation and plot. These properties have been evaluated by measuring the thermodynamic parameters of natural rubber composites compounded with varying percent volume fractions (5% - 25%) of two fillers- clay and corn cob. The results indicated that the maximum values of ΔG and ΔH was obtained for corn cob filled composites at 10% volume fraction, while the optimal values of ΔS for the same composites was found to be at 5% and 25% volume fraction. At lower filler concentration (5 – 17.5%), corn cob filled composites were observed to have higher modulus than clay filled rubber composites, while at these concentration ranges, clay was found to impact higher tensile strength to natural rubber than corn cob filler.
... SEM images show an irregular pattern and an amorphous surface. In Figure 4(d), can be seen a microfiber, product of the second alkali treatment (bleaching) (Alemdar & Sain, 2008;Ogunsuyi & Olawale, 2021) . ...
Article
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Obtaining cellulose from agro-industrial waste offers the possibility of generating added value to solid biomass that is currently deposited in sanitary landfills. This research performed the evaluation of a residue from cocoa husk pods (Theobroma cacao L.), from the agricultural industry. The cellulose fiber was obtained through chemical treatments with KOH at 5% w/v to remove non-cellulosic components and then the fiber was bleached with 3% v/v hydrogen peroxide. The changes in chemical structure were determined through Fourier transform infrared spectroscopy (FTIR). The FTIR analysis confirms the progressive decrease of lignin and hemicellulose after applying chemical treatment. The morphological changes in the surface of the fiber were characterized using the SEM technique. The mass percentage of cellulose increases up to 68 %. It is expected that the Nano-Crystals (NCC) extracted from the biomass of the cocoa husk pods, present a high index of crystallinity and that they are also in suitable conditions to be useful as reinforcing agents in polymeric or mineral matrices, and may have potential application for technology transfer.
... FTIR analysis was used to study PCL-and CNC/PCL-reinforced nanofiber composites (Fig. 7). As the CNC content of PCL increased, the peak at around 3300 cm −1 (telescopic vibrational peak of O-H groups (Alemdar and Sain 2008) increased in size. The strong absorbance peaks at 3000 to 2850 cm −1 corresponded to C-H bond stretching vibrations (Sun et al. 2011). ...
Article
Three-dimensional printing (3DP) has high flexibility and controllability, and has attracted extensive attention in the biomedical field. However, the scaffolds prepared only by 3D bioprinting have poor mechanical properties, and they cannot effectively carry the required drugs. At the same time, compared with the size of cells, the pore size of 3D printed scaffolds is relatively large, and the efficiency of cell inoculation and tissue formation are still limited by the pore resolution of scaffolds. Therefore, a new method of forming 3D printing trachea composites is proposed. When combined, 3D bioprinting and electrospinning (ESP) can overcome the issues associated with scaffolds prepared by 3D bioprinting alone. Nanofibers create a suitable environment for cell growth. In terms of material use, Polycaprolactone (PCL) is commonly used as an ideal material source for 3D printing, but its biomechanical properties are insufficient. Cellulose nanocrystals (CNC) can effectively improve the properties of polymers such as PCL. Therefore, the inner layer of the scaffold used in tracheal surgery is created from PCL/CNC composite by 3D bioprinting, and the outer nano-cellulose film is deposited on the inner surface by electrospinning. Mechanical properties and cell adhesion/growth of scaffolds prepared by 3D bioprinting combined with electrospinning were found to be superior to those of scaffolds prepared by 3D bioprinting.
... Cellulose can be isolated from different plant sources, such as leaves, fruits, wood, cereal straws, roots, agricultural residues, etc. [6,7]. Currently, nanocellulose is more preferably extracted from bacterial sources than plant sources because of its chemical purity, larger contact angle, better permeability to liquid and gases, elevated water holding capacity, and mechanical robustness [8]. ...
Article
Tissue engineering aims to exploit the regenerative capacity of cells and connect the inherent ability of the body to repair and regenerate. Cells are seeded onto a porous three-dimensional scaffold in tissue engineering, which will provide protection and direct cells to the development of new tissue-like structures. These scaffolds can provide a medium for the delivery, under controlled conditions of growth factors release and drug delivery. Herein, nanocellulose was extracted from Ixora coccinea L. plant root, plasticized scaffold of nanocellulose were prepared by using glycerol, gelatin, and PEG 600 followed by morphological characterized by FTIR, XRD, SEM, and tensile modulus analysis. FTIR indicated extracted nanocellulose is without any hemicelluloses, lignin, and non-cellulosic materials. XRD data displayed the extracted nanocellulose has a crystal size of around 3.6 nm while SEM data revealed the fiber diameter was around 20 µm. In the tensile modulus analysis, 1% PEG 600 exhibited the highest (tensile strength 69 MPa with young’s modulus 67.326 MPa) as compared to glycerol and gelatin and hence selected for further studies. The In vitro cytocompatibility studies revealed that nanocellulose and 1% PEG 600 incorporated nanocellulose scaffolds were cell-friendly, promote cell proliferation, and do not show RBC aggregation as well as haemolysis suggesting its potential in various tissue engineering applications. The novelty of this work is that the nanocellulose extracted from the root of I. coccineahas traditional medicinal values in Ayurveda.
... Physical, biochemical, and biological methods have all been utilised to separate NFCs from a variety of resources, with physical/mechanical treatments being the most popular one. Mechanical methods used to remove CNF include high stress homogenization, cryocrushing, and grinding [56][57][58]. Alkali treatments are used in chemical treatments, while enzymatic therapies are used in biological treatments [59,60]. Researchers frequently use a combination of these strategies to achieve the ...
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Cellulose is a group of materials that can be made into low-cost devices because they are the most common biomaterials in nature. Cellulose-based polymers are flexible, biocompatible, biodegradable, and easy to functionalise and mass produce. Cellulosic substrates are attractive biosensing platforms because of their unique properties, exceptional simplicity, and compatibility with standard technologies. Furthermore, cellulose-based biosensing approaches can meet the following criteria for optimal diagnostic assays or devices: real-time connectivity; simplicity of specimen collection; affordability; specificity; sensitivity; user-friendliness; speed and robustness; and deliverability to end-users. As a result, cellulose is suitable for constructing novel analytical devices in the biosensing community. The use of cellulose as a nano-engineered matrix material has enabled recent advancements in biosensors. Several methodologies for producing cellulose-based composites for the fabrication of various biosensors have been described and reviewed. Biological macromolecules have immense importance in genetic and pathogenicity detection. Likewise, there are many research reports, but there is a gap regarding review in this area of biological macromolecule detection like nucleic acids and proteins. This study looked at this previously unexplored area as well as the unique features that make it a good choice for biosensing applications and the engineering features of cellulose-based biosensors. It also looked at how different analytical systems have used such matrices to detect biological macromolecules (DNA, proteins, and RNA) in different samples.
... The spectra had a broad band at 3446 to 2890 cm −1 that corresponded to stretching of Hbonded -OH groups and methyl, and methylene units C-H stretching absorption at 2890-2850 cm −1 . These findings support the work of Alemdar and Sain [35], who investigated the characterization of nano-fibres derived from agricultural residues-wheat straw and soy hulls. ...
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Biomass systems are based on a wide range of feedstock, like food and agricultural waste. The quest for bio-adsorbents that are environmentally benign is the rationale for this study. Thus, the research is aimed at the isolation, physicochemical, and BET analysis of cellulose obtained from Pentaclethra macrophylla Benth Pod (PMBP) biomass waste. The powdered PMBP was dewaxed with toluene and ethanol (2:1) and, thereafter, treated with aqueous sodium hypochlorite (7.5% at 70 o C) and sodium hydroxide (17.5%w/v at 80 o C) to obtain isolated cellulose. Proximate, ultimate, and chemical composition analysis reveals the presence of cellulose (42.7%), hemicelluloses (7.8%), lignin (38.5%), silicon (40.72%), aluminium (17.10%) and elements. The FTIR and Raman spectroscopic analysis revealed some of the functional groups associated with isolated cellulose and raw PMBP. The presence of hemicelluloses and lignin in the isolated cellulose implies that the isolation process did not remove all the impurities. The BET analysis reveals a better specific surface area, pore volume, and average pore diameter or size of the isolated cellulose, and could serve as a better adsorbent than the raw. As a result of the increased surface area and high percentage of isolated cellulose in PMBP, it can be used as a sustainable energy source as well as for the environmental remediation of heavy metals.
... Wang et al., 2015), and ultrasound sonics (Tischer et al., 2010) are widely reported. The process has low product yield and the hydrophilic nature of cellulose causes irreversible agglomeration during the drying process and compounding in nonpolar matrices (Hu et al., 2017), While the chemical treatment methods such as refining (Stelte and Sanadi, 2009), DES hydrolysis , alkaline-acid treatment (Alemdar and Sain, 2008b), sulfuric acid (Rajan et al., 2020), phosphotungstic acid (Lu et al., 2016), chemical modified (Hietala et al., 2013), TEMPO-oxidized (Hietala et al., 2014), enzymes (Yassin et al., 2019), ionic liquid (Voronova et al., 2006) has shown 60-80 % product yield with large effluent generation. ...
Article
A twin-screw extrusion processing has been developed for compounding the reinforced thermoplastic starch for food packing applications. The reinforcement material was developed from the bamboo pulp through green processing technique (hydrated deep eutectic solvent (DES) hydrolysis and continuous ultrasonication). Hydrolysis with 50 % DES provided an optimum yield of 83.34 % with a 20–40 nm particle size distribution. The starch compounded film with 5 % cellulose nanofiber achieved a tensile strength of 5.07 ± 0.15 MPa and was comparable to commercially available biodegradable starch-polybutylene adipate terephthalate film (5.77 ± 2.03 MPa). The reinforcement of nanofiber in starch decreases the melt flow index and hydrophilic nature with enhanced thermal stability by 27.64 %. The film achieved 11.6 g/m²/day water vapor transmission rate that addressed the shelf-life required for bio composite packing. Biodegradability studies for films confirm a 70–85 % degradation within 60 days. Antimicrobial studies confirm the non-inhibitory nature of the prepared biodegradable composites.
... In addition, it is also readily accessible to physical or chemical modifications (Li et al. 2021). CNF can be synthesized by agro-waste and incorporated as Fig. 6 Conversion methodologies of agro-waste to biofertilizer (Du et al. 2018) reinforcing filler in biocomposites (Alemdar and Sain 2008). In transparent nano cellulosic film, the carbon dots enhance UV blocking characteristics and protect from microbial growth (Feng et al. 2017). ...
Article
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Agricultural waste residues (agro-waste) are the source of carbohydrates that generally go in vain or remain unused despite their interesting morphological, chemical, and mechanical properties. With rapid urbanization, there is a need to valorize this waste due to limited non-renewable resources. Utilizing agro-waste also prevents the problems like burning and inefficient disposal that otherwise lead to immense pollution worldwide. In addition, conversion of biomass to value-added products like earthen cups, weaving baskets, and bricks is equally beneficial for the rural population as it provides secondary income, creates jobs, and improves rural people’s lifestyles. This review paper will discuss an overview of different applications utilizing agro-waste residues. In particular, agro-wastes used as construction material, bio-fertilizers, pulp and paper products, packaging products, tableware, heating applications, biocomposites, nano-cellulosic materials, soil stabilizers, bioplastics, fire-retardant additive, dye removal, and biofuels will be summarized. Finally, several commercially available agro-waste products will also be discussed, emphasizing the circular economy.
... Wheat straw consists of about 33%-40% cellulose, 20-25% hemicellulose and 15-20% lignin [8]. Using agricultural leftovers in biomaterials now has potential to release the possibilities of these underutilized recyclable sources while also providing a non-food market for the agricultural industry [9]. ...
Article
Wheat straw and Sugarcane bagasse are agricultural as well as industrial wastes rich in lignocellulosic components that can be extracted easily and used as a renewable source of energy. The main aim of this present work was to explore the alternative source of cellulose extraction using simple, fast, and eco-friendly conditions. The process involves NaOH degradation, acid hydrolysis, and bleaching using hydrogen peroxide as a bleaching agent. The extracted compound was analyzed by XRD and FTIR techniques. The XRD peaks obtained were specific to cellulose Iβ which is a crystalline allomorph with a monoclinic structure. The crystallite size of cellulose obtained from sugarcane bagasse was 10.51 nm which is larger than the size of cellulose obtained from wheat straw i.e 4.04 nm. Cellulose from sugarcane bagasse showed a crystallinity index of 51.84 % whereas wheat straw showed only 17.94 %. The yield was slightly higher in wheat straw than in sugarcane bagasse. FTIR analysis in sugarcane bagasse showed a characteristic peak at 3255.84 cm-1 which is shifted to 3340 cm-1 in the case of wheat straw. This peak is due to the vibration of the –OH group in both of the materials. However, both of the materials showed the vibration of the C-O-C bond at 1033 cm-1.
... The researchers have investigated alternative value-added application of jute sticks in different fields, viz. pulp and paper industries, bio-fuel production [4] composite making [5] activated carbon and microcrystalline cellulose [6] in order to uplift the socio-economic status of the jute cultivators and also to commercialize jute sticks in diversified fields. Keeping this in mind, the objective of the present study is to synthesize 101 microcrystalline cellulose from jute stick through mechanical and chemical pre-treatment process. ...
Article
Synthesis of microcrystalline cellulose (MCC) from jute sticks has been studied and reported in this work. The successful removal of lignin and hemi-cellulose has been confirmed through Fourier Transform Infrared (FTIR) spectroscopic technique. X-ray Diffraction (XRD) technique has been used to measure the crystal size and crystallinity index. The FTIR analysis revealed that the acid hydrolysis had an effect on the crystalline of the fibre; however it did not influence the chemical components of the fibres. Pharmaceutical standard tests were done. Higher concentration of sodium chlorite produces minimum particle size and the effective thermal degradation occurs at 340 °C.
... Cellulose can be extracted from a broad range of plants and animals. Moreover, it can be obtained from various agricultural wastes such as wheat husks, straw, and soybeans [323,324], coconut husk fibers [325], mulberry [326] etc. Thus, people do not cause additional damage to the environment using waste for cellulose production. ...
Article
The presented review is an attempt to systematize the enormous scientific knowledge accumulated over several decades in the field of electrorheology. The review examines the basic principles of the elec-trorheological effect and its physical foundations, approaches of rheological description, and widely uses experimental techniques and methods. A roadmap for modern electrorheological fluids has been proposed. Various compositions of electrorheological fluids and the types of used fillers are considered in detail. The exceptional wideness of the operational characteristics of materials with electrorheological activity is shown, as well as their areas of application. The general modern research trends and directions that are still being developed are also noted. Particular attention of researchers is directed to materials with a low concentration of the dispersed phase and a contrasting transition from viscous to elastic behavior under an electric field. In this regard, fillers with high aspect ratio are widely considered for electrorheological fluids. It is assumed that this review will be useful not only for a novice reader who has just become familiar with the concept of electrorheological fluids, but also for an experienced researcher, in order to better understand the nature of the effect. The review can promote to reach the goal of creating materials with tunable and predetermined properties.
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Benefiting from excellent mechanical properties, large surface area, rich hydroxyl groups, good sustainability, etc., nanocellulose is highly promising for various applications. However, intense chemical treatment and long-term processing are usually required to fabricate nanocellulose. Herein, a new synthesis method of nanocellulose is developed by using ultraviolet light irradiation-assisted delignification and subsequent sonification. This method is more cost-effective, time-saving, and environmentally benign compared to most of previously reported synthesis methods of nanocellulose. The obtained nanocellulose contains a small amount of lignin, which is unfavorable for high-temperature stability and optimal transparency. However, a small amount of lignin is beneficial to mechanical properties and in-water stability. With this nanocellulose, flexible MnO2 cathode film and hydrogel electrolyte are constructed and a quasi-solid-state zinc-ion battery is assembled. The battery exhibits 233.3 mAh g–1 after 1000 cycles at 1 A g–1 and 20 ℃. And more than half of that capacity can be maintained at –20 ℃. The battery also possesses great rate capability and good endurance to external forces. This work provides new insights into the synthesis and application of nanocellulose.
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Sugarcane bagasse, a sugar industry waste, has plentiful cellulose. The present work was aimed to prepare the quality nanocellulose with different polymorphs, nanocelluloses I (NC-I) and II (NC-II) utilizing natural deep eutectic solvents (choline chloride and oxalic acid dihydrate) combined with mechanical treatment from purified cellulose (celluloses I and II), which were prepared from sugarcane bagasse, and to further compare the structural and rheological properties of NC-I and NC-II. Results showed that the yields of NC-I and NC-II were 73.66 ± 0.11 % and 75.15 ± 0.08 %, respectively. Morphology indicated that NC-I had a needle-like appearance with a length of 769.9 ± 76.4 nm and a width of 4.9 ± 1.3, while NC-II displayed a rod-like profile with a smaller size (length: 196.3 ± 50.1 nm; width: 14.9 ± 3.8 nm). Structural characterization revealed that both NC-I and NC-II had high purity, good thermal stability (>300 °C) and high crystallinity (85.5 % and 86 %, respectively). Rheological and zeta potential properties revealed that NC-I suspension had bigger shear resistance, viscoelasticity and lower zeta potential, resulting in better storage stability compared with NC-II suspension. Therefore, the NC-I and NC-II with different characteristics may have potential applications in multiple fields, such as the food, pharmaceutical, and chemical industry.
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The presence of natural hormones in water resources has gained considerable attention in recent years due to their capacity to cause imbalances in several biological systems. Studies have shown that estrone (E1), 17β-estradiol (E2), and estriol (E3) have a high contamination potential even in low concentrations. Thus, new methods are needed to remove these contaminants directly at the source. The present study evaluated the use of the in natura soybean hull as a biosorbent for the removal of estrone (E1), 17β-estradiol (E2), and estriol (E3) from swine manure, using single and multi-component systems. Best hormone removal conditions were performed at room temperature (25 oC) with no pH adjustment. Equilibrium for a single component (SC) and multi-component (MC) systems was reached in 1 h for E1 and 2 h for E2 and E3, and the kinetics were well described by the pseudo-first-order model. Ternary equilibrium models indicated that there was no competition among the hormones. For the MC system, Langmuir model showed maximum adsorption capacities of 2.560 mg g⁻¹, 1.978 mg g⁻¹ and 0.835 mg g⁻¹ for E1, E2, and E3, respectively. Thermodynamic analysis indicated that the adsorption was favorable and spontaneous with physisorption characteristics. The hydrogen-bonding represented the primary adsorption mechanism between the hormones and the adsorbent. The in natura soybean hulls, used as an adsorbent, showed to be promising for removing hormones present in the biofertilizer (swine manure), with characteristics that allow the adsorbent to remain together with the biofertilizer at its final destination. Therefore, an environmentally friendly technology.
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Industrial wastewater is causing serious health problems due to presence of large concentrations of toxic metals. Removal of these metals is still a big challenge using pristine natural biopolymers due to their low surface area, water solubility, and poor recovery. Developing biopolymeric composites with other materials has attained attention because they possess a high surface area and structural porosity, high reactivity, and less water solubility. In simple words, biopolymeric nanohybrids have great adsorption capacity for heavy metals. Biopolymeric materials are abundant, low cost, biodegradable, and possess different functional moieties (carboxyl, amine, hydroxyl, and carbonyl) which play a vital role to adsorb metal ions through various inter-linkages (i.e., electrostatic, hydrogen bonding, ion exchange, chelation, etc.). Biopolymeric nanohybrids have been proven a potent tool in environmental remediation such as the abatement of heavy metal ions from polluted water. Herein, we have reported the adsorption potential of various biopolymers (cellulose, chitosan, pectin, gelatin, and silk proteins) for the removal of heavy metals. This review discusses the suitability of biopolymeric nanohybrids as an adsorbent for heavy metals, their synthesis, modification, adsorption potential, and adsorption mechanism along with best fitted thermodynamic and kinetic models. The influence of pH, contact time, and adsorbent dose on adsorption potential has also been discussed in detail. Lastly, the challenges, research gaps and recommendations have been presented. This review concludes that biopolymers in combination with other materials such as metal-based nanoparticles, clay, and carbon-based materials are excellent materials to remove metallic ions from wastewater. Significant adsorption of heavy metals was obtained at a moderate pH (5–6). Contact time and adsorbent dose also affect the adsorption of heavy metals in certain ways. The Pseudo-first order model fits the data for the initial period of the first step of the reaction. Kinetic studies of different adsorption processes of various biopolymeric nanohybrids described that for majority of bionanohybrids, Pseudo-second order fitted the experimental data very well. Functionalized biopolymeric nanohybrids being biodegradable, environment friendly, cost-effective materials have great potential to adsorb heavy metal ions. These may be the future materials for environmental remediation.
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Due to the complex and recalcitrant structure of the cell wall, the current process of lignocellulose nanofibrils (LCNF) preparation directly from lignocellulosic biomass presents environmental pollution, large consumption of energy and chemicals, and low economic efficiency. In the previous research, we successfully prepared LCNF from wheat straw. However, the mechanism of different acids with small quantities in the pretreatment of lignocellulose during the preparation of LCNF is unrevealed. Herein, we select six organic and inorganic acids to pretreat wheat straw combined with glycerol swelling and mechanical action to directly prepare LCNF from wheat straw. The chemical, physical, mechanical, and thermal performances of LCNF are systematically investigated. Furthermore, the acidity of different reaction systems (glycerol and glycerol mixture containing varied acids) is evaluated to reveal the potential relationship between the performance of LCNF and varied acids with small quantities. The obtained H2SO4-LCNF film possesses good mechanical performances (the specific tensile stress of 78.4 KN m/kg and specific Young's modulus of 6.0 MN m/kg). Overall, we hope this work could offer theoretical guidance for the large-scale production of LCNF directly from lignocellulosic biomass by varied acid pretreatments.
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Nanocellulose, as the most abundant natural nanomaterial with sustainability, biodegradability, and excellent mechanical properties, has been widely applied in modern electronic systems, such as, in the flexible electrochemical energy storage devices. Herein, a reduced graphene oxide (RGO)/cellulose nanocrystal/cellulose nanofiber (RCC) composite membranes was prepared by using a one-pot method. Compared to the pure RGO membrane, the RCC composite membranes exhibited better mechanical properties and hydrophilicity. In addition, due to the insertion of nanocellulose between RGO sheets and easier for permeation of electrolyte, the RCC composite films showed a specific capacitance as high as 171.3 F·cm-3. Consequently, we constructed a nanocellulose-based symmetric flexible all-solid-state supercapacitor (FASC), in which two RCC composite membranes served as electrodes and a porous cellulose nanofiber membrane acted as separator. This fabricated FASC demonstrated a high volumetric specific capacitance of 164.3 F·cm-3 and a satisfactory energy density of 3.7 mW·h·cm-3, which exceeded that of many other FASCs ever reported. This work will open a new avenue in design of next-generation nanocellulose based, sustainable and flexible energy storage device.
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Defatted rice bran (DRB), an underutilized agricultural waste, was subjected to sequential pre‐treatment steps to isolate the cellulose from the lignocellulosic materials. Further extraction by using 55wt% sulfuric acid combined with ultrasonication was able to produce the nanocellulose (NCso). The results reveal that ultrasonication effectively reduced the particle size and increased the crystallinity of NCso compared to the control (NCcont). Unchanged functional groups and insignificant reduction on the degradation temperature of NCso described the negligible impact of ultrasound on the chemical structure and thermal stability of the extracted nanocellulose. Nanocellulose isolated in this study has potential applications as biocomposite materials and emulsifier in stabilizing emulsion.
Article
In this paper, with cellulose microsphere as the substrate, a polyaniline/cellulose composite was prepared by means of in situ polymerization in supercritical CO2 (SCCO2) environment, and the effect of experimental pressure, temperature, and reaction time on the morphology and electrochemical properties of the composite were explored. In addition, the electrochemical properties of the composite were compared with the one prepared under normal temperature and pressure condition (NPT). The results show that the polymerization time of aniline in SCCO2 is greatly shortened comparing with chemical oxidation of 6 h, and the capacitance of the composite prepared in SCCO2 can reach 391 F·g−1 at the scanning rate of 5 mV·s−1, which is higher than 286 F·g−1 under NPT. After 300 charge–discharge cycles, the capacitance retention of the composite prepared in SCCO2 and NPT are 91% and 83%, respectively. The stability of the composite material prepared in SCCO2 is significantly improved.Graphical abstract
Article
Various oil spill cleanup sorbents have good hydrophobicity and oil separation efficiency, but their practical use has been limited due to the difficult and costly fabrication procedure. The research aims towards material development using the consumption of lignocellulosic agricultural residue for isolating cellulose nanofiber and its forward use to construct a 3D porous structure. A simple freeze-drying technique was used to assemble low-density porous structure. The biodegradable polylactic acid coating was used to alter the wettability from hydrophilic to hydrophobic and the maximum water contact angle value was around 120°. The prepared coated samples were testified for a series of oil/organic solvents-water mixtures. The sorption capacity was in the range of 28–70 g/g. The prepared aerogels were efficiently reused for at least 10 cycles. Developed material was used in continuous oil-water separation to remove oil from the water's surface. The cost analysis was estimated for scaleup production in the future.
Poster
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Harnessing lignocellulosic fractions and bioactive compounds from cocoa pod husks (CPH) and shells can lead to the development of profitable commodity products. Consequently, these cocoa pod shells can generate income for farmers and promote economic development (Lu et al., 2018). Each ton of dry cocoa beans generates 10 to 15 Tons of wet cocoa residue, consisting mainly of pods. Pods are typically left to decompose on the cocoa farm, producing off-odors and exacerbating the spread of plant diseases, including black pod rot (Mansur et al., 2014)
Article
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Globally, developing countries require access to safe drinking water to support human health and facilitate long-term sustainable development, in which waste management and control are critical tasks. As the most plentiful, renewable biopolymer on earth, cellulose has significant utility in the delivery of potable water for human consumption. Herein, recent developments in the application of nanoscale cellulose and cellulose derivatives for water treatment are reviewed, with reference to the properties and structure of the material. The potential application of nanocellulose as a primary component for water treatment is linked to its high aspect ratio, high surface area, and the high number of hydroxyl groups available for molecular interaction with heavy metals, dyes, oil-water separation, and other chemical impurities. The ability of superhydrophobic nanocellulose-based textiles as functional fabrics is particularly acknowledged as designed structures for advanced water treatment systems. This review covers the adsorption of heavy metals and chemical impurities like dyes, oil-water separation, as well as nanocellulose and nanostructured derivative membranes, and superhydrophobic coatings, suitable for adsorbing chemical and biological pollutants, including microorganisms.
Article
In this study, four types of cellulose nanomaterials obtained from wheat straw including cellulose nanocrystals (CNCs), TEMPO oxidized cellulose nanofibers (TCNFs), mechanical‐driven cellulose nanofibers (MCNFs) and lignocellulose nanofibers (LCNFs) were first produced and then separately added to carboxymethyl cellulose (CMC) with different mixing ratio of 1, 3, and 6 wt% to make nanocomposite. Pure CMC film and cellulose microfibers (CFs) reinforced composite were also fabricated. BET test showed that TCNFs and CFs had the highest (124 m2/g) and lowest (3.6 m2/g) specific surface area, respectively. FE‐SEM confirmed that TCNFs and CFs presented the thinnest (8 ± 4 nm) and the thickest (24 ± 7 μm) fibers. The nanocomposite containing TCNFs had a transparency of 56%, while CF‐CMC composite showed the lowest one (18%). After the addition of cellulose nanomaterials the XRD peaks of nanocomposites became narrower and shifted partly to the right side compared to that of pure CMC. The highest and lowest water vapor permeability values obtained for rod‐like CNC reinforced nanocomposite and pure CMC film, respectively. The nanocomposite containing 6 wt% TCNFs showed the highest tensile strength and Young's modulus. Cellulose nanomaterials positively affected on the strain at break of the nanocomposites.
Article
Since natural cellulose is mostly cellulose I and has a fibrous form, most cellulose-based adsorbents are fibrous/rod-shaped and exhibit the cellulose I crystal structure. This study reports a cellulose II-based spherical nanoparticle microcluster adsorbent (SNMA), synthesized from biomass by a bottom-up approach, for removing toxic hexavalent chromium (Cr(VI)). The basic structure of SNMA was investigated. Notably, the prepared adsorbent was a microcluster composed of spherical nanoparticles, while exhibiting cellulose II crystal structure, resulting in higher thermal stability and significantly enhanced adsorption performance. The adsorption process and mechanism of SNMA on Cr(VI) were studied in detail. The SNMA achieved a high adsorption capacity (225.94 mg/g) and receptor site density. The SNMA is expected to be used as a bio-based spherical nanoparticle microcluster adsorbent platform for the adsorption of different toxic substances by changing the surface functional groups of its components, spherical nanoparticles.
Article
Presently on a global scale, one of the major concerns is to find effective strategies to manage the agricultural waste to protect the environment. One strategy that has been drawing attention among the researchers is the development of biocompatible materials from agricultural waste. This strategy implies successful conversion of agricultural waste products (e.g.: cellulose, eggshell etc.) into building blocks for biomaterial development. Some of these wastes contain even bioactive compounds having biomedical applications. The replacement and augmentation of human tissue with biomaterials as alternative to traditional method not only bypasses immune-rejection, donor scarcity, and maintenance; but also provides long term solution to damaged or malfunctioning organs. Biomaterials development as one of the key challenges in tissue engineering approach, resourced from natural origin imparts better biocompatibility due to closely mimicking composition with cellular microenvironment. The “Garbage In, Biomaterials Out (GIBO)” concept, not only recycles the agricultural wastes, but also adds to biomaterial raw products for further product development in tissue regeneration. This paper reviews the conversion of garbage agricultural by-products to the biocompatible materials for various biomedical applications. The agro-waste biomass processed, purified, modified, and further utilized for the fabrication of biomaterials-based support system for tissue engineering applications to grow living body parts in vitro or in vivo.
Article
This study presents the preparation of cellulose micro-nanofibrils (CMNFs) from Enteromorpha (EP) and the application in PVA/acetylated distarch phosphate (ADSP)/CMNFs composite films. The Micro-nano scale, hydrophilicity, and strong hydrogen bond characteristics of CMNFs prepared form EP by acid hydrolysis were confirmed through the granular statistics, XRD analysis and chemical structure analysis. With the addition of CMNFs, the ultimate tensile strength and elongation at break of composite films are increased by 42.4 % and 90.3 %. An original Weibull statistical analysis shows the impact of CMNFs' added amount on strength distribution and ultimate stress. SEM and polarizing microscope images show the CMNFs' dispersion state in that films is optimal, when their addition was to be 2 %-3 % of total dry weight of PVA/ADSP matrix, which is consistent with the results of Weibull modulus analysis. The main thermal weight-loss process of the composite film is divided into four stages, CMNFs can significantly increase the thermostability at 280 °C to 400 °C. The experiment of water contact angle and water vapor transmission rate of the composite films confirmed that CMNFs can improve films' hydrophilicity. This study provides basis for the preparation of hydrophilic CMNFs and mechanism of modification study PVA-based composites.
Book
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Additive (Manufacturing) technology offers the ability to produce personalized products with lower development costs, shorter lead times, less energy consumed during manufacturing and less material waste. It can be used to manufacture complex parts, and enables manufacturers to reduce inventory, make products on-demand, create smaller localized manufacturing environments, and even reduce supply chains. Additive manufacturing (AM), also known as fabricating three-dimensional (3D) and four-dimensional (4D) components, refers to processes that allow for the direct fabrication of physical products from Computer-Aided Design (CAD) models through the repetitious deposition of materials layers. Compared with traditional manufacturing processes, AM allows the production of customized parts from bio and synthetic polymers without the need for molds or machining typical for conventional formative and subtractive fabrication. Today, AM offers numerous advantages, i.e. few assembly required, supply chain efficiencies, sustainability, geometric flexibility, low Buy-to-Fly ratio, shortened time-to-market, environmental, and in the production of single and multiple components, offering incomparable design independence with the facility to manufacture components from various bio and synthetic polymer. These advantages make AM a major player in the next polymer industrial revolution. Polymers and their composites are one of the most widely used materials in today’s industry and are of great interest in AM due to the vast potential for various applications, such as in the apparel, art and jewelry, electric and electronic, healthcare, biomedical, robotics, military defense, sensor and actuators, construction, aerospace and automotive industries. Polymers that are utilized in AM including hydrogels, elastomers, thermosets, thermoplastics, functional polymers, polymer composites, polymer hybrid composites, polymer nanocomposites and polymer blends. Over the past 30 years, many research have been done on developing new polymeric materials for AM processes such as material jetting (MJ), drop on demand (DOD), sand binder jetting, vat photopolymerization, fused deposition modeling (FDM), stereolithography (SLA), digital light processing (DLP), and selective laser sintering (SLS). In this special issue, we aim to capture the cutting-edge of the state-of-the-art in research pertaining to advancing additive manufacturing of polymeric materials. The topic themes include advanced polymeric materials development, processing parameter optimization, characterization techniques, structure-property relationships, process modelling, etc., specifically for AM.
Article
Wheat straw (WS) was considered the most abundant agricultural residue in China. Therefore, it was meaningful to explore the effective utilization of WS. Thus far, WS has been considered a potential raw material to produce lignocellulose nanofibrils (LCNFs) with the rapid development of nanotechnology. Unfortunately, the existing methods of LCNFs preparation directly from WS still faced some hurdles. Herein, screw extrusion and ball milling considered the common mechanical pretreatments were employed to directly prepare LCNFs from WS. The different impacts of screw extrusion and ball milling pretreatments on the properties of LCNFs were revealed by systematically comparing physicochemical analyses. The results showed that the crystalline and chemical structure of samples was little affected by the mechanical pretreatment. However, the mechanical pretreatment caused a change in the morphology, yield, and chemical composition of LCNFs. LCNFs prepared by screw extrusion with a high yield of 73% had the narrowest diameter distribution (0 ~ 80 nm), the most cellulose content (51.1%), and the maximum crystallinity degree (44.7%). LCNF samples all exhibited good thermal stability. This work could not only offer theoretical guidance on the preparation of LCNFs by mechanical pretreatments but also expand the high‐value application of WS in polymer composites. Herein, the morphology, physicochemical structure, chemical composition, and thermostability of Wheat straw (WS) and lignocellulose nanofibrils (LCNFs) were systematically investigated, aiming to reveal the impact of screw extrusion and ball milling during the process of LCNF preparation. This work could not only offer theoretical guidance on the preparation of LCNFs by mechanical pretreatments but also expand the high‐value application of agricultural residues in polymer composites.
Article
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Composites based on natural rubber reinforced with mineral (precipitated silica and chalk) and organic (sawdust and hemp) fillers in amount of 50 phr were obtained by peroxide cross-linking in the presence of trimethylolpropane trimethacrylate and irradiated by electron beam in the dose range of 150 and 450 kGy with the purpose of degradation. The composites mechanical characteristics, gel fraction, cross-linking degree, water uptake and weight loss in water and toluene were evaluated by specific analysis. The changes in structure and morphology were also studied by Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy. Based on the results obtained in the structural analysis, possible mechanisms specific to degradation are proposed. The increasing of irradiation dose to 450 kGy produced larger agglomerated structures, cracks and micro voids on the surface, as a result of the degradation process. This is consistent with that the increasing of irradiation dose to 450 kGy leads to a decrease in crosslinking and gel fraction but also drastic changes in mechanical properties specific to the composites' degradation processes. The irradiation of composites reinforced with organic fillers lead to the formation of specific degradation compounds of both natural rubber and cellulose (aldehydes, ketones, carboxylic acids, compounds with small macromolecules). In the case of the composites reinforced with mineral fillers the degradation can occur by the cleavage of hydrogen bonds formed between precipitated silica or chalk particles and polymeric matrix also.
Article
Cellulose nanocrystals (CNCs) were extracted from jujube seeds by the exertion of sulfuric acid hydrolysis procedure initially and thus, utilizing the alkaline and bleaching treatments. The resultant materials were identified after each stage of treatment. In the following, we performed morphological researches by the usage of field diffusion scanning electron microscopy (FESEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). In addition, the spherical forms of synthesized CNCs were observed with a diameter of 27 nm throughout the FESEM images, while displaying a value of 27.37 nm as well due to TEM micrographs. The obtained Zeta potential displayed a reasonable negative surface charge for CNCs. In conformity to the outcomes of TEM and FESEM, the results of AFM revealed the fine dispersion and spherical form of cellulose nano-particles. Thermogravimetric analysis (TGA) was performed to assess the thermal stability of CNCs, provided by the usage of jujube seeds, and it was suggested by the outcomes that this factor is affected mainly through the induced dehydration by sulphate groups. The obtained spectra from Fourier transform infrared (FTIR) spectroscopy displayed the gradual ejection of non-cellulosic materials (lignin and hemi-cellulose) and determined the affiliation of resulting samples to cellulose species. Jujube and CNC seed crystallization was also investigated through X-ray diffraction (XRD) analysis, which was indicative of the high crystalinity of 87.21%. According to the results of energy dispersive x-ray diffraction (EDX), CNCs contained 0.74 wt% sulfur impurity next to the company of other main components, while the evaluation of CNCs cytotoxicity did not show any cytotoxic effect. The synthesized novel CNC from jujube seed was screened by using an in vitro assay to measure the increases in glucokinase (GK) activity that was stimulated by the glucose concentration of 10 mM. According to the results, this substance proved to be capable of acting as a potent activator for GK. The Ksv values obtained from fluorescence quenching for GK-glucose and GK-glucose-CNC were 4.98 × 10³ M⁻¹ and 8.95 × 10³ M⁻¹ respectively. Spectral results revealed the conformational changes in GK upon interaction with glucose-CNC with higher binding affinity than to glucose. The circular dichroism spectroscopy indicates that the secondary structure of GK is changed in the presence of glucose and glucose-CNC.
Article
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This study presents the isolation, characterization, and kinetic analyses of cellulose nanocrystals (CNCs) from date palm waste in the United Arab Emirates. After bleaching date palm stem waste with acidified NaClO2 and delignification via NaOH treatments, cellulose was extracted. Mineral acid hydrolysis (62 wt % H2SO4) was performed at 45 °C for 45 min to produce crystalline nanocellulose. Fourier transform infrared (FTIR) and chemical composition analysis confirmed the removal of noncellulosic constituents. The crystallinity index increased gradually with chemical treatments, according to the obtained X-ray diffraction (XRD) results. Thermogravimetric analysis and differential scanning calorimetry results revealed that the CNC has high thermal stability. The Coats-Redfern method was used to determine the kinetic parameters. The kinetic analysis confirmed that CNC has more activation energy than cellulose and thus confirms its compact and resistive crystalline structure. This has been attributable to the stronger hydrogen bonding in CNC crystalline domains than that in cellulose crystalline domains. Scanning electron microscopy revealed that lignin and hemicellulose were eliminated after chemical pretreatments, and CNC with a rodlike shape was obtained after hydrolysis. Moreover, transmission electron microscopy confirmed the nanoscale of crystalline cellulose. ζ potential analysis indicated that the CNC afforded a stable suspension (-29.27 mV), which is less prone to flocculation. Kinetic analyses of cellulose and cellulose nanocrystals isolated from date palm waste are useful for making composites and designing selective pyrolysis reactors.
Article
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Soil mulch composite films composed of biodegradable materials are being increasingly used in agriculture. In this study, mulch films based on wheat straw fiber and an environmentally friendly modifier were prepared via in situ polymerization and tested as the ridge mulch for crops. The mechanical properties of the straw fiber film were significantly enhanced by the modification. In particular, the films exhibited a noticeable increase in dry and wet tensile strength from 2.35 to 4.15 and 0.41 to 1.51 kN/m, respectively, with increasing filler content from 0% to 25%. The contact angle of the straw also showed an improvement based on its hydrophilicity. The crystallinity of the modified film was higher than that of the unmodified film and increased with modifier content. The changes in chemical interaction of the straw fiber film were determined by Fourier transform infrared spectroscopy, and the thermal stability of the unmodified film was improved by in situ polymerization. Scanning electron microscopy images indicated that the modifier was uniformly dispersed in the fiber film, resulting in an improvement in its mechanical properties. The modified straw fiber films could be degraded after mulching for approximately 50 days. Overall, the superior properties of the modified straw fiber film lend it great potential for agricultural application.
Article
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Cellulose nanofibers are obtained from various sources such as flax bast fibers, hemp fibers, kraft pulp, and rutabaga, by chemical treatments followed by innovative mechanical techniques. The nanofibers thus obtained have diameters between 5 and 60 nm. The ultrastructure of cellulose nanofibers is investigated by atomic force microscopy and transmission electron microscopy. The cellulose nanofibers are also characterized in terms of crystallinity. Reinforced composite films comprising 90% polyvinyl alcohol and 10% nanofibers are also prepared. The comparison of the mechanical properties of these composites with those of pure PVA confirmed the superiority of the former.
Article
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The microstructure, thermal and mechanical properties of flax and wheat straw fibres have been examined with a view to using these natural fibres as reinforcing additives for thermoplastics. In this regard, the fibres were characterized prior to incorporation into the polymer, using a range of techniques, including SEM, image analysis, thermogravimetric analysis and micro-mechanical tensile testing, at room and elevated temperatures. The thermal and mechanical properties obtained have been discussed in relation to the measured composition and structural form of the fibres.
Article
Plant fiber reinforced thermoplastic composites have gained much attraction in structural applications such as building and automotive products. Agricultural residues such as wheat straw, bagasse, and corn stover can also be exploited as readily available natural fiber resources for similar applications. The objective of this study was to extract fibers from wheat straw and also to determine the usefulness of fungal retting of wheat straw before extracting the fibers. Wheat straw was mechanically defibrillated using a laboratory-scale mechanical refiner before and after fungal retting. Fiber characteristics such as physico-chemical and mechanical properties, surface characteristics, and thermal properties of the resultant fibers were measured in order to explore the possibilities of using the fibers as reinforcing materials. Retted fibers were stronger than un-retted fibers. The length and diameter of the retted fibers were lower than the un-retted fibers. FT-IR spectroscopic analysis of the wheat straw fibers indicated the fractional removal of hemicelluloses and lignin from the retted fiber. X-ray photoelectron spectroscopy (XPS) of the fibers showed the partial removal of extractives from the surface of the retted fibers. Also, the oxygen to carbon ratio (O/C) of the fibers illustrated that there is more lignin type surface structure for both retted and un-retted fibers. However, slightly higher ratio of oxygen to carbon in the retted fiber indicated a more carbohydrate-rich fiber than the un-retted fiber. Thermal degradation characteristics demonstrated the suitability of processing wheat straw fibers with thermoplastics.
Article
Thermal analysis has recently become prominent, particularly in applications to fibers, plastics, and other synthetic polymeric materials. Thermal analysis may be defined as a set of techniques used to describe the physical or chemical changes associated with substances as a function of temperature [1]. Thermograms have been used to determine thermodynamic and kinetic parameters associated with the chemical changes which occur upon heating, the heat capacity of a substance, first- and second-order transition temperatures, latent heats of transformation, and effects of radiation or additives on natural and synthetic polymers. Particularly successful appears to be the simultaneous use of two or more thermal analytical techniques or the combination of thermal analytical and spectroscopic techniques (for example, infrared, electronic, and nuclear magnetic resonance analysis). The increasing commercial importance of polymers and the commercial manufacture of thermal analytical instruments have resulted in rising interest and intensified research in this field, with the number of articles published yearly on thermal analysis rapidly increasing. The journals Thermochimica Acta (published by Elsevier), the Journal of Thermal Analysis (published by the Hungarian Academy of Sciences), and the Japanese Journal of Calorimetry and Thermal Analysis are today the major sources of information on thermal analysis. The first two deal solely with reports of thermal analytical research.
Article
Treatment of dewaxed maize stems, rye straw, and rice straw with 1 M NaOH at 30 °C for 18 h resulted in a dissolution of 78.0, 68.8, and 82.1% of the original lignin, and 72.1, 72.6, and 84.6% of the original hemicelluloses, respectively. The three alkali lignin fractions and three hemicellulosic preparations and the corresponding residues (mainly cellulose) were characterized by both degraded methods, such as alkaline nitrobenzene oxidation and acid hydrolysis, and non-destructive techniques, e.g. ultraviolet (UV), Fourier transform infrared (FT-IR), carbon-13 nuclear magnetic resonance spectroscopies (13C-NMR), and gas permeation chromatography (GPC). It was found that the three lignin preparations contained substantial amounts of non-condensed guaiacyl and syringyl units with fewer p-hydroxyphenyl units, and had weight-average molecular weights between 3280 and 3890 g mol−1. The two hemicellulosic preparations, obtained from maize stems and rye straw, were dominant in glucuronoarabinoxylans. While the hemicelluloses present in rice straw were mainly composed of α-glucan and k-arabino-(4-O-methyl-d-glucurono)-d-xylan. The thermal analysis of the polymers showed that hemicelluloses degraded in first place, while lignin showed less degradation, and therefore, its structure was more stable. Cellulose, on the other hand, showed an important degradation process, mainly between 250 and 330 °C, and its thermal stability is lower than that of lignin, but higher than that of hemicelluloses.
Article
Water at 40° removes from acetone extracted soy bean hulls a galactomannan in 2% yield. The ratio of D-galactose units to D-mannose units is 2:3. Periodate analysis as well as examination of the products from hydrolysis of the methylated polysaccharide indicate the presence of a chain of 1 → 4 linked D-mannopyranose units with D-galactopyranosyl units joined to certain D-mannose units by 1 → 6 linkages. The structure is similar to guaran but is of lower molecular weight.
Article
The mechanical behavior of films cast from sugar beet cellulose microfibrils was investigated through tensile tests. The obtaining of these microfibrils by chemical and mechanical treatments from the raw beet pulp is described. Depending on their purification level, individualization state, and moisture content, differences in tensile modulus are observed. It is found that pectins act as a binder between the cellulose microfibrils, which tends to increase the Young's modulus in dry atmosphere and to decrease it in moist conditions. The extraction of the cellulose microfibrils from the sugar beet cell wall and the obtainment of microfibril suspensions with partial individualization of the microfibrils by a mechanical treatment lead to the formation of a network of cellulose microfibrils within the film, which in turn increases the tensile modulus. Furthermore, the effect of the remaining pectins is compared with the effect of pectins previously removed and added to completely purified cellulosic microfibrils. As expected, once removed and so partly degraded, those pectins have nearly no influence on the mechanical properties. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1185–1194, 1997
Article
Annual crop fibres are rich in cellulose and they are a cheap and rapidly renewable source of fibres with potential for polymer reinforcement. Straw fibres have been incorporated in a polyester resin matrix and the properties of the fibre and composite determined. The fibres have a Young's modulus of approximately 8 GN m–2 and an effective density of 5.1 kN m–3 when combined with resin. Useful composites can be formulated with an optimum fibre volume fraction of about 0.61, resulting in a flexural stiffness of 7.3 GN m–2 and flexural strength of 56 MN m–2. The specific flexural stiffness is about 2.5 times greater than that of polyester resin and about half that of softwoods and GRP. The work of fracture measured in impact is about half that of softwoods. It is envisaged that alternative methods for processing the fibres and the use of a phenolic resin matrix will improve the composite properties further. Straw-based composites are suitable as core material for structural board products.
Article
The microstructure and mechanical properties of polypropylene composites containing flax and wheat straw fibres are discussed. Particular emphasis has been given to determining the nature and consequences of fibre damage induced during melt-processing operations, fibre orientation occurring in mouldings, and possible interfacial adhesion between the matrix and fibres. Compared to unfilled polypropylene, addition of flax and wheat straw caused a significant increase in tensile modulus, particularly, in the case of flax fibres, which also gave higher tensile yield strength and Charpy toughness, despite a lack of interfacial bonding. Tensile strength was increased further through inclusion of 5% by weight of maleic anhydride-modified polypropylene, which was shown to promote adhesion between fibres and matrix.
Article
Environmentally friendly composite materials can be prepared using wood fibers and/or various types of agro-derived fibers as reinforcements. In this study, agro-residues such as wheat straw and corn stem filled polypropylene were prepared and their suitability was investigated as a reinforcing filler in thermoplastics and as an alternative to the wood flour filled plastics. Effect of compounding techniques, compatibilizer and fungal treatment of agro-residues on the mechanical properties of the composites were evaluated. It was found that high shear compounding of wheat straw fibers exhibited similar properties to that produced by the milled wheat straw. This may be due to the extensive fiber breakage occurred during the high shear compounding that results in a similar aspect ratio to that of milled straw. Compatibilizer is needed for improving the strength properties of the agro-residue filled PP composites. Fungal treatment of milled wheat straw did not show much improvement in the strength properties of the composites. Comparison of mechanical properties of the agro-residue filled PP with that of the wood flour and the old newsprint filled PP showed the suitability of the agro-residues as alternative filler for thermoplastics.
Article
The treatment of wheat straw with 2% H2O2 at 50°C and pH 11.5 for 4–30 h or with 2% H2O2–0.05% anthraquinone at 50°C and pH 11.5 for 4.5 h resulted in the release of 79–86% of the original lignin and 77–91% of the original hemicelluloses, which contained 3.8–6.5% of associated lignins. Xylose was the major sugar constituent in all the solubilized hemicellulosic fractions, and arabinose, glucose, and galactose were present in small amounts. The isolated seven hemicellulosic samples were further characterized by Fourier transform infrared, and carbon-13 magnetic resonance spectroscopy as well as gel permeation chromatography. Comparison of these hemicellulosic fractions with those obtained by alkali extraction from wheat straw in the absence of hydrogen peroxide provided evidence of similar chemical composition and structure. The treatment by alkaline peroxide under the conditions used did not result in any significant change in the macromolecular structure of hemicelluloses.
Article
The present paper investigates the effect of fiber treatment on the mechanical properties of unidirectional sisal-reinforced epoxy composites. Treatments including alkalization, acetylation, cyanoethylation, the use of silane coupling agent, and heating were carried out to modify the fiber surface and its internal structure. As indicated by infrared spectroscopy, X-ray diffraction and tensile tests, variations in composition, structure, dimensions, morphology and mechanical properties of the sisal fibers can be induced by means of different modification methods. When the treated fibers were incorporated into an epoxy matrix, mechanical characterization of the laminates revealed the importance of two types of interface: one between fiber bundles and the matrix and the other between the ultimate cells. In general, fiber treatments can significantly improve adhesion at the former interface and also lead to ingress of the matrix resin into the fibers, obstructing pull-out of the cells. As a result, the dependence of laminate mechanical properties on treatment methods becomes complicated. On the basis of a detailed analysis, the relationship between optimized fiber treatment and performance improvement of sisal composites was proposed.
Article
By aqueous alkaline extraction of commercial soybean hull holocellulose, there is obtained a crude hemicellulose B fraction in 6% yield. The major polysaccharidc from this fraction is isolated by alcohol fractionation and is electrophoretically homogeneous; [α]D25 +57.3 ° with a number-average molecular weight of 40,800. It contains 17.7% glucuronic acid isolatable in the aldobiouronic acid 2-O-(4-O-methyl-α-d-glucopyranosyluronic acid)-d-xylose. Hydrolysis of the fully methylated polysaceharide yields 2-O-methyl-d-xylose, 2,3-di-O-methyl-d-xylose, 2,3-di-O-methyl-d-glucose, 2,3,4,6-tetra-O-methyl-d-galactose, and 2,3,5-tri-O-methyl-l-arabinose and 2,3,4-tri-O-methyl-d-xylose in the ratio 2.4:2.0:1.5:1.5:1.0. Thus, the polysaccharide is branched with d-xylose, l-arabinose, and d-galactose as end units and d-xylose and d-glucose at points of branching.
Article
The isolation of cellulose from wheat straw was studied using a two-stage process based on steam explosion pre-treatment followed by alkaline peroxide post-treatment. Straw was steamed at 200 degrees C, 15 bar for 10 and 33 min, and 220 degrees C, 22 bar for 3, 5 and 8 min with a solid to liquid ratio of 2:1 (w/w) and 220 degrees C, 22 bar for 5 min with a solid to liquid ratio of 10:1, respectively. The steamed straw was washed with hot water to yield a solution rich in hemicelluloses-derived mono- and oligosaccharides and gave 61.3%, 60.2%, 66.2%, 63.1%, 60.3% and 61.3% of the straw residue, respectively. The washed fibre was delignified and bleached by 2% H2O2 at 50 degrees C for 5 h under pH 11.5, which yielded 34.9%, 32.6%, 40.0%, 36.9%, 30.9% and 36.1% (% dry wheat straw) of the cellulose preparation, respectively. The optimum cellulose yield (40.0%) was obtained when the steam explosion pre-treatment was performed at 220 degrees C, 22 bar for 3 min with a solid to liquid ratio of 2:1, in which the cellulose fraction obtained had a viscosity average degree of polymerisation of 587 and contained 14.6% hemicelluloses and 1.2% klason lignin. The steam explosion pre-treatment led to a significant loss in hemicelluloses and alkaline peroxide post-treatment resulted in substantial dissolution of lignin and an increase in cellulose crystallinity. The six isolated cellulose samples were further characterised by FT-IR and 13C-CP/MAS NMR spectroscopy and thermal analysis.
Article
The potential of wheat straw fibers prepared by mechanical and chemical processes as reinforcing additives for thermoplastics was investigated. Fibers prepared by mechanical and chemical processes were characterized with respect to their chemical composition, morphology, and physical, mechanical and thermal properties. Composites of polypropylene filled with 30% wheat straw fibers were prepared and their mechanical properties were also evaluated. The fibers prepared by chemical process exhibited better mechanical, physical and thermal properties. Wheat straw fiber reinforced polypropylene composites exhibited significantly enhanced properties compared to virgin polypropylene. However, the strength properties of the composites were less for chemically prepared fiber filled composites. This was due to the poor dispersion of the fibers under the processing conditions used. These results indicate that wheat straw fibers can be used as potential reinforcing materials for making thermoplastic composites.
Isolation of Cellulose Nanofibers from Renewable Feed Stocks and Root Crops
  • A Bhatnagar
Bhatnagar, A., 2004. Isolation of Cellulose Nanofibers from Renewable Feed Stocks and Root Crops. PhD thesis, University of Toronto.
US Patent Pending, Application No. 60/512
  • A Bhatnagar
  • M Sain
Bhatnagar, A., Sain, M., 2003. US Patent Pending, Application No. 60/ 512, 912.
Mechanical behavior of sheets prepared from sugar beet cellulose microfibrils
  • A Dufresne
  • J Caville
  • M Vignon
Dufresne, A., Caville, J., Vignon, M., 1997. Mechanical behavior of sheets prepared from sugar beet cellulose microfibrils. J. Appl. Polym. Sci. 64, 1185-1194.