No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Influence of Surface Flour Treatment on the Thermal, Structural and Morphological Properties of Polypropylene/ Spartium Junceum Flour Composites
Abstract
Vegetable flour (Spartium junceum) reinforced polymer composites provide the customers with more alternatives in the material market due to their unique advantages. The effects of Spartium junceum (SJ) flour content and coupling agent concentration on the composite properties were studied. The above samples were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (ATG), X-ray diffraction (XRD), and scanning electron microscopy. The results obtained from XRD indicated that the incorporation of SJ flour involves a shift to lower 2 of the other polypropylene peaks.
... This group is responsible to improve the compatibilization between the fibers and the polymer matrix by establishing covalent bonds between them. Therefore, the silane coupling agents' function as a bridge between the fibers and the matrix [17][18][19]. ...
... This increase is due to the better dispersion of the filler and particularly to the reinforcement of interfacial bonds between PS polystyrene and olive pomace flour. Explain by the ability of silane to form strong interfacial bonds between the PS and OPF and therefore a better stress transfer between matrix and olive flour [17,30]. Figure 6 shows the evolution of the elongation at break of composites as a function of the load rate. ...
This paper aims to disclose the effects of surface modification on the morphological, thermal and mechanical properties of olive pomace flour (OPF) reinforced polystyrene composites. First, the OPF was treated by the silane coupling agent: 3-(Trimethoxysilyl) propyl methacrylate (TMSPMA). Then, the treated OPF was added to polystyrene (PS) at different ratios, creating the composite samples. The structural and property changes resulting from this treatment were observed and discussed through Fourier transform infrared spectroscopy (FTIR), morphological analysis, thermal analysis and mechanical analysis. The results show that, with the growing OPF content, the tensile strength and elongation at break of the composites decreased, while the Young’s modulus increased; the composites prepared with the silane coupling agent were more thermally stable than the untreated composites; the filler-matrix interaction was improved through the surface modification of the OPF by the TMSPMA).
... The silane coupling agents provide bridges between the fibers and the matrix. [17][18][19] Boussehel 20 prepared composites of polystyrene (PS) with 3-(trimethoxysilyl) propyl methacrylate grafted on the olive pomace flour as a coupling agent to enhance the interfacial bonding between that flour and PS -and thus to improve morphological, thermal and mechanical properties of PS. Composites of PS with fillers such as silica and carbon black were created using coupling agents such as fluorine substituted styrene compounds and styrene compounds containing triethoxy(4-vinylphenylethyl) silane functional groups. ...
Ecologically friendly composites have been made on the basis of wood sawdust and sillylated styrene as the binder. That binder acts simultaneously as a reinforcing agent. The surface structures were studied by a scanning electron microscopy and energy dispersive X-ray microanalysis. The bending strength increases with the increase in temperature from 453 to 493 K at the constant pressure of 15 MPa. Likely we have heterogeneous reactions between active groups of triethoxysilylated styrene and sawdust, which lead to increasing of the spatial (per specific volume) concentration of chemical bonds. Impact viscosity increases in the same temperature range from 14.6 to 25.8 kJ/m2. Water absorption determined after 3 and 24 h varies over a wide range in the function of the composition. The lowest value is 4.1 wt% water after 24 h
... Spanish broom (Spartium junceum) has been subject of several previous scientific researches in the field of polymer biocomposites. Moreover, different matrices such as polypropylene (PP) [10,[21][22][23], low density polyethylene (LDPE) [24], polyvinyl chloride (PVC) [25] and polylactic acid (PLA) [26] have been compounded with Spanish broom fiber or flour to prepare biocomposites. The current work brings a supplementary contribution and aims to take advantage of the low cost, low density, recyclability, biodegradability and the abundant local fibers crops which is Spanish broom for application as potential reinforcement agent for PP matrix. ...
This work presents the chemical modification of Spanish broom flour (SBF), and the study of SBF loading and surface treatment on the performances of polypropylene (PP) biocomposites. In order to enhance the interfacial interactions between the PP matrix and the SBF, two types of chemical treatments were used: 2 wt% of sodium hydroxide (NaOH) for different times (8, 24 and 48 h) and 5 wt% of vinyltrimethoxysilane (VTMS), respectively. Different techniques for characterization such as the melting flow index (MFI), X-ray diffraction, transient plane source (TPS) and water absorption were used. The experiment results showed a decrease of the MFI with increasing of modified SBF content, independently of the type of the chemical treatment. Moreover, this decrease became significant in the biocomposites containing SBF-VTMS. The X-ray patterns showed that surface treatment of SBF could improve their crystallinity and crystallite sizes. The TPS measurements illustrates that the thermal conductivity of the biocomposites decreases with 10 wt% of modified SBF loading. Higher content than 20 wt% of SBF, improved the thermal conductivity of the biocomposites. Meanwhile, the lowest values were found when the VTMS is used. Besides, it was accompanied by a decrease in absorptivity due to the better interfacial adhesion SBF-PP.
This study investigates the morphology and properties of biocomposites based on a blend of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly (lactic acid) (PLA) 50/50 (w/w) reinforced with untreated (UNDF) and alkali-treated (ATDF) Diss (Ampelodesmos mauritanicus) fibers at 20 wt. %. Moreover, PHBV-g-MA used as the compatibilizer was added at 5 wt. % to the alkali-treated biocomposites. Morphology, and crystallinity, thermal, thermo-mechanical, rheological and mechanical properties of PHBV/PLA biocompo-sites were studied. The study showed that the treated Diss fibers were uniformly dispersed in both PLA and PHBV phases. This results in a good interfacial adhesion between the components, as observed by scanning electron microscopy (SEM). Further, the results also indicated that the compatibi-lized biocomposite samples showed an enhancement in crystallinity degree and heat deflection temperature (HDT) passing from 48.7% to 62.4% and 119.2 to 132.9 C, respectively, in comparison with the neat blend. Similar trend is also observed with the tensile data indicating a significant increase in Young's modulus by almost 48.5% compared to PHBV/PLA matrix. This is due to better interactions between Diss fibers and PHBV/PLA matrix. The results suggest the occurrence of a synergistic effect between PHBV-g-MA and alkali-treated Diss fibers in the development of materials with interesting properties and could be a potential means to expand their applications.
Environmental pollution problems, especially air pollution, seriously endanger public health globally. Facing the severe air pollution, air filters still have many challenges, especially in terms of filtration performance and filtration stability. Herein, a zeolitic imidazolate framework-8/polypropylene-polycarbonate bark-like meltblown fibrous membrane (PPC/ZIF-8) was designed through meltblown and in-situ growth method, achieved efficient PM2.5 capture and great filtration stability under harsh environment. After in-situ growth, the PPC/ZIF-8 membrane can dramatically enhance the PM2.5 filtration efficiency without increasing the pressure drop, the PM2.5 filtration efficiency and quality factor up to 32.83 % and 116.86 % higher than pure PPC membrane, respectively. Moreover, through five filtration-wash-dry cycles, the PM2.5 filtration performance is still at a high level. This PPC/ZIF-8 membrane provides a new strategy for the preparation of air filter with excellent comprehensive filtration performance.
Pine cone and Spartium junceum are readily available cellulosic materials which can be used as reinforcements in thermoplastic-based composites. In the present study, flours issued from Pine cone (PCF) and Spartium junceum (SjF) were first chemically modified with maleic anhydride (MA) and silane. Then, neat and treated flours were incorporated into a polypropylene (PP) matrix and the properties of composites prepared without or with maleic anhydride-grafted-polypropylene (PP-g-MA), added as a compatibilizer, were compared. FTIR analysis proved the efficiency of the treatments in removing some non-cellulosic components and formation of ester linkages due to the reaction between MA and the flours hydroxyl groups. In the case of Silane-PCF, the bands observed around 1730 cm⁻¹ and 1241 cm⁻¹ disappeared, thus indicating that the silane treatment allowed the extraction of hemicellulose and lignin from the flour surface. X-rays diffraction results showed that the applied chemical treatments contributed in increasing the flours crystallinity index, which implies that by the removal of the amorphous material covering the fibers, the more crystalline cellulosic component of the fibers is exposed. The incorporation of PCF and SjF increased the composites crystallinity which emphasizes their significant role in heterogeneous nucleating of PP matrix. Additionally, the composites observation by electron microscopy revealed more intimate contact between the flours and PP matrix after surface modification which permitted the dissolution of impurities. As a result, treated PCF and SjF induced a significant increase in the composites resilience and decreased notably their water uptake aptitude relatively to the composites based on untreated flours.
The aim of this work was to study the effects of alkali and alkali-silane surface treatments on Spartium junceum (Sj) fibers characteristics. Then, untreated and surface treated fibers were incorporated into a poly(lactic acid) matrix and the properties of the composites were studied. To improve the adhesion at the interface between the PLA matrix and alkali-silane treated fibers, maleic anhydride-grafted poly (lactic acid) (PLA-g-MA) was added as a compatibilizer. FTIR and TGA analysis proved the efficiency of the alkali treatment in removing some non-cellulosic components, namely hemicelluloses and lignin. Also, XRD results showed that the applied chemical treatments contribute to the increase in the crystallinity index of the Sj fibers. The incorporation of Sj fibers was found to decrease notably the impact strength of PLA and to affect its thermal behavior by increasing the melting temperature of the composites. However, it has been observed that the treatments increased notably the composites impact properties. These results have been confirmed by scanning electron microscopy (SEM) observations of the composites fractured surfaces which revealed a more intimate contact between the Sj fibers and the PLA matrix after surface modification. Also, the PLA-g-MA acted positively on the adhesion in the interfacial region.
This study investigates the effects of surface treatments by sodium hydroxide (NaOH) and vinyltrimethoxysilane (VTMS) of Spartium junceum (SJ) fibers on the structural and physical properties of Spartium junceum fibers. SJ fibers were characterized by Fourier Transform Infrared (FTTR) spectroscopy, X-ray diffraction (XRD) and optical microscopy. FTBR was performed to see the extent of chemical modification of the fibers, the results obtained from XRD indicated an improvement in the crystallinity index of the SJ fibers by treatments. The effects of the treatments on the properties of the prepared SJ fiber reinforced poly(vinyl chloride) (PVC) composites were investigated. Also, the treatments improved notably the mechanical properties of the composites. The observations by scanning electron microscopy (SEM) of fracture surfaces of PVC/SJ composites showed more intimate contact between fibers and PVC matrix after surface modification.
In this investigation, naturally woven coconut sheath, a new type of reinforcement was used. The composite was fabricated using compression molding machine. The mechanical properties like tensile, flexural and impact strengths were studied according to the ASTM standards. For comparison, conventionally used glass fiber-reinforced composites were also fabricated and tested. In all the testing, the coconut sheath-reinforced polyester composite showed enhanced results. For further improvement in the properties, chemical modification such as silane treatment was given to the fibers. As expected, the mechanical properties of coconut sheath-reinforced composites were improved.
The effect of silane treatments on the water absorption properties of mercerized bamboo matting reinforced polyester composites were investigated. Treatments using γ-Aminopropyltriethoxy silane, 3-trimethoxysilylpropyl methacrylate, Vinyltris(2-methoxyethoxy)silane, Bis[3-(triethoxysilyl)propyl] tetrasulfide, 3-aminopropyltrimethoxy silane and n-Octyltrimethoxy silane were carried out to improve the water resistant property of the bamboo fibers. Water absorption in the composites was studied by long-term immersion and 2 h boiling in distilled water. The process of absorption of water was found to follow the kinetics and mechanism described by Fick's theory. Alkali treatment results in reduction of water absorption from 51% to 35%. Further reduction is observed with silane treatment. Water absorption varies between 19% and 44%, the minimum being for aminopropyl triethoxy silane-treated composites.
In this study, the thermal properties of bio-flour-filled, polypropylene (PP) bio-composites with different pozzolan contents
were investigated. With increasing pozzolan content, the thermal stability, 5% mass loss temperature and derivative thermogravimetric
curve (DTGmax) temperatures of the bio-composites slightly increased. The coefficient of thermal expansion (CTE) and thermal expansion
of the bio-composites decreased as the pozzolan content increased. The glass transition temperature (T
g), melting temperature (T
m) and percentage of crystallinity (X
c) of the bio-composites were not significantly changed. The thermal stability, thermal expansion and X
c of the maleic anhydride-grafted PP (MAPP)-treated bio-composites were much higher than those of non-treated bio-composites
at 1% pozzolan content due to enhanced interfacial adhesion. X-ray diffraction (XRD) analysis confirmed the crystallinity
of pozzolan-added bio-composites. From these results, we concluded that the addition of pozzolan in the bio-composites was
an effective method for enhancing the thermal stability and thermal expansion.
The effects of coupling agents on the mechanical, morphological, and water sorption properties of luffa fiber (LF)/polypropylene(PP) composites were studied. In order to enhance the interfacial interactions between the PP matrix and the luffa fiber, three different types of coupling agents, (3-aminopropyl)-triethoxysilane (AS), 3-(trimethoxysilyl)-1-propanethiol (MS), and maleic anhydride grafted polypropylene (MAPP) were used. The PP composites containing 2–15 wt% of LF were prepared in a torque rheometer. The tensile properties of the untreated and treated composites were determined as a function of filler loading. Tensile strength and Young's modulus increased with employment of the coupling agents accompanied by a decrease in water absorption with treatment due to the better adhesion between the fiber and the matrix. The maximum improvement in the mechanical properties was obtained for the MS treated LF composites. The interfacial interactions improved the filler compatibility, mechanical properties, and water resistance of composites. The improvement in the interfacial interaction was also confirmed by the Pukanszky model. Good agreement was obtained between experimental data and the model prediction. Morphological studies demonstrated that better adhesion between the fiber and the matrix was achieved especially for the MS and AS treated LF composites. Atomic force microscope (AFM) studies also showed that the surface roughness of LFs decreased with the employment of silane-coupling agents.
Natural fiber reinforced polymer composites (NFPCs) provide the customers with more alternatives in the material market due to their unique advantages. Poor fiber–matrix interfacial adhesion may, however, negatively affect the physical and mechanical properties of the resulting composites due to the surface incompatibility between hydrophilic natural fibers and non-polar polymers (thermoplastics and thermosets). A variety of silanes (mostly trialkoxysilanes) have been applied as coupling agents in the NFPCs to promote interfacial adhesion and improve the properties of composites. This paper reviews the recent progress in using silane coupling agents for NFPCs, summarizes the effective silane structures from the silane family, clarifies the interaction mechanisms between natural fibers and polymer matrices, and presents the effects of silane treatments on the mechanical and outdoor performance of the resulting composites.
This paper reports on the effect of additives on the properties of injection moulded composites based on polypropylene (PP) and high density polyethylene (HDPE) filled with wood and cellulose flour. Three types of additives were studied: dispersion aids, elastomeric additives, and adhesion promoting agents. Some of the dispersion aids were found to improve the filler dispersion and the impact strength. The modulus remained relatively unaffected while the strength was lowered. The high molecular weight elastomeric additives increased the impact strength and ductility, while the stiffness was reduced. An adhesion promotor based on a maleic anhydride modified polypropylene was found to behave as a true coupling agent, i.e. the strength and ductility increased, the melt strength was improved, and also the hot water resistance was raised. The experimentally determined composite moduli are found to agree relatively well with theoretical predictions. The effect of processing on the shape and size of the filler particles is evaluated using automatic image analysis.
The composites investigated in this article were polypropylene reinforced with Spanish broom (Spartium junceum) fibers. These fibers were modified with N[-3 Trimethoxysilyl propyl] ethylene diamine (Z6020) or stearic acid, which work as coupling agents between fibers and matrix. This work studied the thermal (differential scanning calorimetry) and thermomechanical (dynamic mechanical thermal) analysis. The surfaces of the composites were characterized by electron microscopy. It was found that silane-treated fiber composites show superior properties compared with the specimens made of pure polypropylene. Microscopic observations correlate with these results.
The thermal and crystallization behavior of PP/Spartium junceum fiber composites were studied by thermogravimetry (TGA) and differential scanning calorimetry (DSC). The surface modification of Spartium junceum fibers was carried out using silane coupling agents in order to improve the interfacial adhesion between the fiber and the matrix. The effects of fiber content and chemical treatment on thermal properties were evaluated. It was found that Spartium junceum fiber degraded before the PP matrix but the thermal stability of the PP/Spartium junceum fiber composites was higher than those of the fiber and the matrix. DSC measurements showed that the incorporation of Spartium junceum fiber caused an increase in the crystallinity of the matrix. These effects have been attributed to the fact that the surfaces of Spartium junceum fibers act as nucleating agents for the crystallization of the polymer, promoting the growth and the formation of transcrystalline regions around the fibers.
Short date palm tree lignocellulosic fibres have been used as a reinforcing phase in commodity thermoplastic matrices (polypropylene-PP and low density polyethylene- LDPE). Both unmodified and compatibilized fibres were used. Compatibilization was carried out with the use of maleic anhydride copolymers. The morphology, thermal and mechanical properties of the ensuing composites were characterized using scanning electron microscopy, differential scanning calorimetry and tensile tests. The reinforcing capability of the unmodified fibres was found to depend on the nature of the matrix and the main parameter governing the composite behaviour was the degree of crystallinity of the matrix. Compatibilization was reported to enhance the mechanical performances for both sets of composites up to a critical amount of compatibilizer beyond which the degree of crystallinity of the matrix decreases.
In this research, sisal fibre reinforced polypropylene (SF/PP) composites were prepared by injection moulding using a pre-coating technique that we have developed earlier. The composite specimens were subjected to hot water immersion treatment at 90 °C for different durations. The effects of the immersion treatment on the tensile and impact fracture characteristics were investigated. The apparent weight gain and weight loss curves were constructed. From the weight loss curves for the individual composites, the weight loss within the induction period was negligible. At the end of the induction period, the weight loss increased sharply. Due to the weight loss and the formation of additional moisture diffusion paths as immersion treatment proceeds, the apparent weight gain was non-Fickian. Both the tensile modulus and tensile strength of the SF/PP composites decreased continuously with increasing water immersion time. On the contrary, the Izod impact strength increased initially with immersion treatment. After reaching the maximum impact strength, the impact strength was found to decrease with further increase in immersion time. These contradictory behaviours between the tensile and impact properties were explained by the plasticization of the SF/PP interface and the swelling of the reinforcing sisal fibres.
In the present study, Spartium junceum (SJ) fibers were chemically treated with different concentrations of two coupling agents, silane N [-3 Trimethoxysilyl propyl] ethylene diamine (Z-6020) and stearic acid, in order to improve the mechanical properties of polypropylene/Spartium junceum fibers (PP/SJ) composites. The chemical modification efficiency was verified by FTIR analysis which showed the appearance of bands around 1260 and 1100 cm attributed to asymmetric stretching of Si-O-Si linkage and Si-O-Cellulose for (Z-6020) modified SJ fibers. The mechanical properties of the composites prepared from chemically treated Spartium junceum fibers are found to increase substantially compared to those with untreated ones.
Wood fiber reinforced polypropylene composites containing different types of wood fiber (hard and softwood fiber) were prepared by an injection molding and a compression molding process. Influence of different processing systems and compatibilizer on the composite mechanical properties was investigated. The present study investigated the tensile, flexural, charpy impact, and impact properties of wood-fiber reinforced polypropylene composites as a function of processing system and compatibilizer. From the results, it is observed that injection molding process showed better tensile and flexural properties comparative with compression molding process, which is about 155% and 60% for tensile strength, and flexural strength, respectively. Charpy impact strength increased the maximum in compression molding for hard-wood fiber-PP (PP) composites, and it is about 70% at the wood-fiber content of 30%. Impact resistance in injection molding process shows better performance comparison to compression molding process and damping index decreased the most at about 60% in injection molding process for hard-wood fiber-PP composites at the wood-fiber content of 50%. Scanning electron microscopy of the composites also is investigated to better understand the interaction between wood fiber and polypropylene in both processing systems.
The suitability of using polypropylene modified with an organosilane as a coupling agent for polypropylene/wood-flour composites was investigated. The tensile properties, the water-absorption behavior, the thermal degradation properties and the morphology of the composites were analyzed and compared with those of non-coupled composites and of composites coupled with polypropylene modified with maleic anhydride. The coupling agents were prepared in the laboratory and it was verified that the silane showed higher reactivity towards PP chains. The results indicated that the silane-modified polymer increased the interfacial adhesion between the fibers and the polymer matrix and this effect was better than that obtained for the maleated-polypropylene-coupled composites.
In this study, the possibility of using silane technology in crosslinking composites of wood flour and polyethylene has been investigated. Composites of vinyltrimethoxy silane grafted high density polyethylene and wood flour were produced by compounding in a twin-screw extruder. Gel content analysis with p-xylene extraction revealed higher gel content in the samples where wood flour was added compared to neat crosslinked matrix. Mechanical analysis of the crosslinked composites showed increased tensile strength with increasing amount of wood flour, which might be an indication of improved adhesion between the matrix and the wood flour. The stiffness increased with increasing amount of wood flour with accompanied decrease in strain at break. Dynamic mechanical thermal analysis of crosslinked plastics and composites showed no significant shift in the γ-transition towards higher temperature for the composites compared to neat plastic. Short-term creep experiments showed reduced creep deformation with increasing amount of wood flour. Crosslinking of the composites reduced the creep deformation further. A boiling test in water followed by tensile testing showed that the crosslinked composites were less susceptible to water uptake compared to the non-crosslinked. Moreover, the decrease in tensile strength of the crosslinked composites was not as significant as for the non-crosslinked composites. Scanning electron microscopy revealed good compatibility and adhesion between the plastic and the wood flour for crosslinked composites.
Natural fibres such as jute, coir, sisal, bamboo and pineapple are known to have high specific strength and can be effectively used in composites in various applications. The use of hemp fibres to reinforce the polymer aroused great inter- est and expectations amongst scientists and materials engineers. In this paper, composites with isotactic polypropylene (iPP) matrix and hemp fibres were studied. These materials were manufactured via the patented FIBROLINE process based on the principle of the dry impregnation of a fibre assembly with a thermoplastic powder (iPP), using an alternating electric field. The aim of this paper is to show the influence of fibre/matrix interfaces on dielectric properties coupled with mechan- ical behaviours. Fibres or more probably the fibre/matrix interfaces allow the diffusion of electric charges and delocalise the polarisation energy. In this way, damages are limited during mechanical loading and the mechanical properties of the composites increase. The structure of composite samples was investigated by X-ray and FTIR analysis. The mechanical properties were analysed by quasistatic and dynamic tests. The dielectric investigations were carried out using the SEMME (Scanning Electron Microscope Mirror Effect) method coupled with the measurement of the induced current (ICM).
The paper reports on the processing and properties of composites consisting of thermoplastics and cellulose-based fillers. The plastics used were HDPE, PP, PS, SB, PA 6, and PA 12; the fillers were wood flour (white spruce), cellulose flour (bleached sulphate, pine) and cellulose fibre (bleached sulphate, birch). The mixtures were homogenized (kneader, alternatively single-screw extruder) before being injection moulded into tensile test bars. The modulus increased with the filler content, while the yield and breaking stress remained relatively unaffected. For HDPE, SB, and PA 12 a moderate increase in the strength level was noted. The extension at rupture and the impact strength fell sharply when the filler content was increased. The compounding method had no influence on the modulus. Kneader compounding, producing a higher homogeneity, gave in general higher strength and impact values than compounding in a single-screw extruder. The temperature dependence of the modulus was highly reduced, as was also the mould shrinkage. At processing temperatures in excess of 200°C, severe discolouration was noted.Cellulosic fillers may be regarded as low-reinforcing fillers comparable to untreated mineral products such as calcium carbonate. On the other hand, the materials used here have the advantage of a substantially lower density.
Morphological and structural investigation of textile artefacts recovered from Pompeii, Herculaneum and Scafati was successfully carried out by scanning electron microscopy (SEM), optical microscopy (OM) and wide angle X-ray scattering (WAXS). The majority of the samples were carbonized as a result of the eruption of the Vesuvius volcano in the yearad79 and therefore were blackish-brown coloured and very brittle. Only two textile fragments were recovered in a good state of preservation; the first was a cloth fragment characterized by a brown colour with green spots, the second was flock and peculiarly brown-green coloured. SEM, OM and WAXS studies allowed the identification of the nature, origin and molecular structure of the natural fibres and the determination of the kind of weaves used. In addition, cotton, broom, hemp, kapok and Graminae fibres, all obtained from seeds, stems and leaves, were recognized. Ovidae wool and Angora wool fibres coming from animal skin and byssus fibres coming from secretion of the Pinna mollusc were also found. Plain cloth and twill essential weaves were identified, together with derived weaves such as reps. The cassimere composite weave obtained without using a loom by intertwining parenchyma tissue of Graminae leaves was also recognized.
This paper presents the influence of Spartium junceum (SJ) fiber content, surface treatment and temperature on the water uptake of polypropylene/Spartium junceum fiber (PP/SJ) composites. Composites specimens were dried at 70°C to reach a constant weight and then were submerged in distilled water at different temperatures, 23°C and 85°C. Water uptake of PP/SJ fiber composites was found to increase with fiber content. Impact strength properties are dramatically affected by the water absorption. Water-saturated samples present poor impact strength. The SEM micrograph of Spartium junceum fiber untreated and treated with silane (Z-6020) illustrate the reduction of roughness via surface treatment of fiber.
We describe how poly(lactic acid)/sweet sorghum fiber composites were made by melt compounding and compression molding. Four different kinds of surface treating agents (amino silicone oil (ASO), silane coupling agent (SCA), emulsified wax (EW) and titanate coupling agent (TCA)) were used to modify the natural fiber surface to reduce hydrophilicity. Fourier Transform Infrared Spectroscopy and X-Ray Photoelectron Spectroscopy data indicated that the SSF surfaces were successfully covered by treating agents. And the hydrophilic property of modified fiber characterized by the contact angle measurements. With the test of mechanical properties, PLA/TCA-F composite showed the maximum flexural strength, 60 MPa, which is 63% than that of the control. Fourier Transform Infrared Spectroscopy data indicated that the chemical reaction between TCA-F and PLA matrix played a prominent role in the high mechanical properties of PLA/TCA-F composites.
Sisal fiber (SF) surface modification was carried out by grafting with methyl methacrylate (MMA) using cerium and ammonium nitrate as initiator. The effects of reaction time, monomer, and initiator concentration on the grafting parameters were systematically investigated. The results showed that MMA was successfully grafted onto the sisal fiber surface. The PMMA-grafted sisal fibers were melt blended with polypropylene (PP) and then injection molded. The PP/SF composites were characterized by means of thermal analysis, mechanical testing, wide-angle X-ray diffraction, and SEM examination. PMMA grafted onto the surface of SF enhanced the intermolecular interaction between the reinforcing SF and PP matrix, improved the dispersion of SF in the PP matrix, and promoted the formation of β-crystalline PP. These enhanced the thermal stability and mechanical properties of PP/SF composites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1055–1064, 2003
The fusion process, melting temperature and heat of fusion of carefully crystallized fractions of isotactic polypropylene (molecular weights from 5·4 × 104 to 2·2 × 105) have been investigated. The equilibrium melting temperature, obtained by the extrapolation method in experiments involving very low degrees of crystallinity, corresponds to 208°. The fusion enthalpy was found to be 1·386 cal/mole. This low value and the high depression of Tmo suggest a relatively high interfacial energy; a value of 285 erg/cm2 is estimated for σec.
The thermal and viscoelastic properties of polypropylene (PP)/cellulose as well as PP/Xylan composites were investigated
by differential scanning calorimetry (DSC) and dynamic mechanical thermoanalysis (DMTA). Morphological aspects were available
by using polarizing light microscopy and scanning electron microscopy (SEM). Three types of fillers were incorporated in PP:
xylan fillers (XL), cellulose microfibers (CM) and short fibers of spun cellulose (CS). The compatibilizer maleic anhydride
modified PP (MAPP) was added to the composites. The crystallization temperature and crystallinity of PP apparently increased
in the presence of all fiber types. The cellulose fiber surfaces act as nucleating agents for PP, resulting in the formation
of transcrystalline regions around the fibers. The DMTA spectra of PP/filler composites revealed a significant increase in
the stiffness and a remarkable decrease of the damping values. This effect was stronger for PP/CS than for the other composites.
The results verify that improved compatibility and interfacial adhesion between fiber and matrix markedly contribute to an
improvement of the mechanical properties.
The aim of this work was to compare the effect of modification way of short flax fibre bundle/polypropylene (PP) composites on mechanical properties. Modification was carried out on fibre surface and also modifying PP matrix using several amounts of maleic anhydride-polypropylene copolymer (MAPP) as compatibilizer. The optimum doses of two different MAPP compatibilizers have been obtained. The effect of fibre bundle loading on composite mechanical properties was also analysed. The influence of water uptake on the sorption characteristics of composites has been studied by immersion in distilled water at room temperature. The effects of fibre bundle loading and also the use of MAPP modification on both water sorption and mechanical properties were also evaluated. Results showed that using MAPP as coupling agent, mechanical properties of composites improved, and water uptake rate clearly decreased. However, after long period of water immersion mechanical properties drastically decreased. On the other hand, mechanical recycling of flax fibre bundle/PP composites has been shown to be feasible.
The thermal and crystallisation behaviour of sisal/PP composites was studied by thermogravimetry (TG), differential scanning calorimetry (DSC) and polarising optical microscopy. Chemical modifications were made to sisal fibre using a urethane derivative of polypropylene glycol (PPG/TDI), maleic anhydride modified polypropylene (MAPP), and KMnO4 in order to improve the interfacial adhesion between the fibre and matrix. The thermal properties of the blends were analysed by TG analysis. The effects of fibre content and chemical treatments on the thermal properties were evaluated. It was found that treated fibre composites show superior properties compared to the untreated system. DSC measurements exhibited an increase in the crystallisation temperature and crystallinity, upon the addition of fibres to the PP matrix. This is attributed to the nucleating effects of the fibre surfaces, resulting in the formation of transcrystalline regions. On increasing the fibre content, the melting peak of the PP component was shifted to higher temperatures suggesting a constrained melting. The thickness of the transcrystalline layer formed depends on crystallisation temperature and time. The transcrystalline growth rate was slow in the quiescent state. On the other hand, upon the application of stress, transcrystallinity developed quickly. In fact, the shear stress at the polymer/fibre interface initiated the nucleation. Fibre surface modification by PPG/TDI increases the nucleating ability of sisal fibre to a very small extent.
The properties of cellulose fiber and PMMA- or PBA-grafted cellulose fibers are investigated as a function of the initiator (ceric-ammonium nitrate) concentration and the amount of grafted polymer onto cellulose fiber. The molecular weight of cellulose decreases while the crystallinity increases with an increment of initiator concentration because of the partial degradation of the amorphous zone of the fibers exposed to the oxidation by the initiator. This results in a reduction of the elastic modulus and tensile strength at high initiator concentrations. Degradation of cellulose is partially inhibited during the grafting process and, therefore, the effect of initiator on the mechanical properties is less notorious in the grafted cellulose fiber. The grafting of PMMA or PBA on the fiber results in lower mechanical properties than those of the ungrafted cellulose fiber. The reduction of the elastic modulus is independent of the amount of grafted PMMA or PBA, but the tensile strength decreases with the PBA content on the PBA-grafted fiber. Either the grafted or the ungrafted cellulose fibers improve the mechanical properties of plasticized PVC composites, and the best results are obtained for PMMA-grafted cellulose fibers because of the better fiber–matrix adhesion. The Halpin–Tsai equation seems to better agree with the experimental data when there is a good fiber–matrix adhesion. In contrast, for poor fiber–matrix adhesion the experimental data has a better agreement with the parallel arrangement equation.
An account is given on natural and man-made cellulose fiber reinforced plastics. Possible applications of this material group are detailed. A survey is also discussed about physical and chemical treatment methods that improve fiber matrix adhesion, as well as their results and effects on the physical properties of composites. The results show that natural fibers can be processed with the already commonly applied methods: glass mat thermoplastic matrix (GMT, sheet moulding compound (SMC) or bulk moulding compound (BMC).
Chemical treatment of natural reinforcements can enhance their adhesion to polymer matrices. This work reports the effects of different treatments on the fibre–matrix compatibility in terms of surface energy and mechanical properties of composites. The composites were compounded with two kinds of flax fibres (natural flax and flax pulp) and polypropylene. The applied treatments were maleic anhydride (MA), maleic anhydride-polypropylene copolymer (MAPP) and vinyl trimethoxy silane (VTMO). The treatment effects on the fibres have been characterised by Infrared Spectroscopy. Two techniques have been used to determine the surface energy values: the Dynamic Contact Angle method for the long flax fibres and the Capillary Rise method for the irregular pulps. The use of different methods involves a small discordance in the wettability values. Nevertheless, the three treatments reduce the polar component of the surface energy of the fibre. Composites containing MAPP-treated did the highest mechanical properties, whilst the MA and VTMO-treated fibre gave similar values to that for the untreated ones.
The main objective of this research was to study the potential of grain by-products such as wheat husk, rye husk as reinforcements for thermoplastics as an alternative or together with wood fibres. Thermal degradation characteristics, bulk density, water absorption and solubility index were also investigated. The particle morphology and particle size was investigated by scanning electron microscopy. Water absorption properties of the fibres were studied to evaluate the viability of these fibres as reinforcements. The chemical composition of fibre such as cellulose, hemicellulose, lignin, starch, protein and fat were also measured. Surface chemistry and functionality of grain by-products was studied by EDX and FT-IR. Polypropylene composites were fabricated using a high speed mixer followed by injection moulding with 40 wt.% of fibre load. Tensile and Charpy impact strength of resulting composites were investigated.
Composites based on recycled high density polyethylene (RHDPE) and natural fibers were made through melt blending and compression molding. The effects of the fibers (wood and bagasse) and coupling agent type/concentration on the composite properties were studied. The use of maleated polyethylene (MAPE), carboxylated polyethylene (CAPE), and titanium-derived mixture (TDM) improved the compatibility between the bagasse fiber and RHDPE, and mechanical properties of the resultant composites compared well with those of virgin HDPE composites. The modulus and impact strength of the composites had maxima with MAPE content increase. The composites had lower crystallization peak temperatures and wider crystalline temperature range than neat RHDPE, and their thermal stability was lower than RHDPE.
Abaca fibre reinforced PP composites were prepared using a high speed mixer followed by injection moulding with 30 wt.% of fibre load. Prior to composite production, the fibres were modified by fungamix and natural enzyme. The effects of modification of the fibre were assessed on the basis of morphology and thermal resistance and as well as on mechanical, thermal and environmental stress corrosion resistance properties of the resulting composites. Coupling agent (MA-PP) was also used with unmodified abaca fibre to observe the coupling agent effect on resulting composites properties. The moisture absorption of the composites was found to be reduced 20–45% due to modification. Tensile strength found to be 5–45% and flexural strengths found to be 10–35% increased due to modification. Modified fibre composites found to better resistance in acid and base medium.
This paper is focused on the interactions between leafwood cellulose fibres and a plasticized wheat starch matrix. Different plasticized starch (TPS)-based composites have been elaborated. LDPE-based composites are used as reference materials (no fibre-matrix interactions). After extrusion and injection moulding, the properties of the different composites are analysed. Mechanical properties (tensile tests), thermomechanical properties (DMTA) and morphology (SEM) are evaluated. DMTA analysis shows for TPS composites a strong evolution of the main relaxation temperature, which can be linked to the existence of cellulose-starch interactions resulting in a decrease of starch chain mobility. This phenomenon is consistent with the evolution of mechanical behaviour. SEM observations correlate this hypothesis. After cryogenic fracture, TPS composites present fibres, which are embedded in the matrix. On the composites, reinforcing effects have been observed according to the evolution of fibre length and fibre content. (C) 2001 Elsevier Science Ltd. Ah rights reserved.
Lignocellulosic fractions from wheat straw were used as natural fillers in composites of a polyolefin (a copolymer of polyethylene and polypropylene) and a biodegradable polyester [poly(butylene adipate-co-terephtha-late)]. The mechanical properties of these injected composites were investigated with tensile and impact testing. A reinforcing effect of wheat-straw residues was found for both types of composites. Compared with the polyester-based composites, the polyolefin composites were more brittle. The addition of compatibilizing agents (-gamma-methacrylo-xypropyltrimethoxysilane, maleic anhydride modified polypropylene, and stearic acid) did not improve the prop-erties of the polyolefin composites. The surface properties were studied with contact-angle measurements, and poor interfacial adhesion was found between the hydrophilic lignocellulosic filler and the hydrophobic polyolefin matrix. Thermal characterization revealed the formation of low intermolecular bonds between the polyester matrix and the lignocellulosic filler, in agreement with the surface tensions results and scanning electron microscopy observations. (C) 2004 Wiley Periodicals, Inc.
Composite Materials with lignocellulosic fibers
- A Bendahou
- Y Habbibi
- H Kaddami
- A Dufresne
Bendahou, A.; Habbibi, Y.; Kaddami, H.; Dufresne, A. Composite
Materials with lignocellulosic fibers. Revue Roumaine de Chimie
2009, 54 (7), 557-563.
SEM micrographs of PP=SJ flour composites (a):(80=20) SJ treated with 4 wt% of silane
- Nekkaa Et
FIG. 13. SEM micrographs of PP=SJ flour composites (a):(80=20) SJ
treated with 4 wt% of silane, (b): (80=20) SJ treated with 5 wt% of silane
and (c): (60=40), SJ treated with 5 wt% of silane.
180
S. NEKKAA ET AL.