Article

Development of formaldehyde-free bio-board produced from mushroom mycelium and substrate waste

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Synthetic adhesives in the plywood industry are usually volatile compounds such as formaldehyde-based chemical which are costly and hazardous to health and the environment. This phenomenon promotes an interest in developing bio-boards without synthetic adhesives. This study proposed a novel application of natural mycelium produced during mushroom cultivation as natural bio-adhesive material that convert spent mushroom substrate (SMS) into high-performance bio-board material. Different types of spent mushroom substrates were compressed with specific designed mould with optimal temperature at 160 °C and 10 mPa for 20 min.. The bio-board made from Ganoderma lucidum SMS had the highest internal bonding strength up to 2.51 mPa. This is far above the 0.4-0.8 range of China and US national standards. In addition, the material had high water and fire resistance, high bonding and densified structures despite free of any adhesive chemicals. These properties and the low cost one step procedure show the potential as a zero-waste economy chain for sustainable agricultural practice for waste and remediation.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... A review of mycelium-based construction materials has revealed a considerable amount of progress over the past decade. Cumulative forms of mycelium-based construction materials include block materials [130], particle board [23,[131][132][133], acoustic materials [44,45,134], thermal insulations [34,39], cladding materials [53], surface materials (thin sheet and film) [63,133,135] and paste material [136] (Figure 5). Block materials are material composites exhibiting foam-like characteristics. ...
... It is then fabricated into a thinner material and shifts its characteristics from foam-like to more cork-like and wood-like characteristics that can be used in various non-structural applications. The varying degrees of thickness have been researched in several studies [23,131,132]. Appels et al. [23] studied the characteristics of an agricultural-by-product mycelium composite comprised of two types of fungus, including P. ostreatus and T. multicolor, through the employment of three fabrication processes (no-press, cold press, and hot-press processes). Improvements in the stiffness and homogeneity of the composite were observed after utilizing the hot-press process. ...
... As a result, the weights of both fungus mycelium composites were lighter than those of the medium-density fiberboard (MDF; 500-1000 kg/m 3 ) and oriented strand board (OSB; 550-700 kg/m 3 ), while the composite still retained the preferred mechanical properties of a conventional wood composite. Khoo et al. [131] investigated mycelium bonding as a natural adhesive in the development of high-strength bio-boards prepared from compressed spent mushroom substrates (SMS) in conjunction with various fungal species. These can minimize the harm associated with formaldehyde-based adhesives that are believed to have hazardous health and environmental effects. ...
Article
Full-text available
The continually expanding use of plastic throughout our world, along with the considerable increase in agricultural productivity, has resulted in a worrying increase in global waste and related environmental problems. The reuse and replacement of plastic with biomaterials, as well as the recycling of agricultural waste, are key components of a strategy to reduce plastic waste. Agricultural waste is characterized as lignocellulosic materials that mainly consist of cellulose, hemicellulose, and lignin. Saprobe fungi are able to convert agricultural waste into nutrients for their own growth and to facilitate the creation of mycelium-based composites (MBC) through bio-fabrication processes. Remarkably, different fungal species, substrates, and pressing and drying methods have resulted in varying chemical, mechanical, physical, and biological properties of the resulting composites that ultimately vary the functional aspects of the finished MBC. Over the last two decades, several innovative designs have produced a variety of MBC that can be applied across a range of industrial uses including in packaging and in the manufacturing of household items, furniture, and building materials that can replace foams, plastics, and wood products. Materials developed from MBC can be considered highly functional materials that offer renewable and biodegradable benefits as promising alternatives. Therefore, a better understanding of the beneficial properties of MBC is crucial for their potential applications in a variety of fields. Here, we have conducted a brief review of the current findings of relevant studies through an overview of recently published literature on MBC production and the physical, mechanical, chemical, and biological properties of these composites for use in innovative architecture, construction, and product designs. The advantages and disadvantages of various applications of mycelium-based materials (MBM) in various fields have been summarized. Finally, patent trends involving the use of MBM as a new and sustainable biomaterial have also been reviewed. The resulting knowledge can be used by researchers to develop and apply MBC in the form of eco-friendly materials in the future.
... Cyclocybe aegerita (specified as Aaegerita agrocibe) [36]; Coprinopsis cinerea [62]; Daedaleopsis confragosa [44]; Flammulina velutipes [77]; Fomes fomentarius [38,83,85,87,108]; Fomitopsis pinicola [63]; "Ganoderma. sp." [21,41,44,61,68,77,110], G. applanatum [87], G. boninense [75], G. lucidum [22,25,31,32,41,69,70,[72][73][74]77,[79][80][81][82][83]89,100,102,106,109,112], G. resinaceum [44,49,86,93,101], G. sessile [61,110]; Inonotus obliquus [67]; Irpex lacteus [42]; Kuehneromyces mutabilis [77]; Laetiporus sulphureus [63]; Lentinula edodes [32,64,77]; Lentinus velutinus [67]; Megasporaporia minor [49]; ...
... Oxyporus latermarginatus [49]; Phaeolus schweinitzii [63]; Piptoporus betulinus [63]; "Pleurotus sp." [33], P. albidus [67], P. citrinopileatus [74], P. djamor [62], P. eryngii [74], P. ostreatus [26,29,32,[35][36][37][38]41,46,56,57,63,74,77,81,82,84,88,90,91,94,96,99,103,105,106], P. ostraceus florida [77], P. ostraceu sajorcaju caju [77], P. salmoneo-stramineus [36]; Polyporus arcularius [63], P. brumalis [59], P. pulmonarius [36]; Pycnoporus sanguineus [67,83,92]; Trametes sp. [53,61]; Trametes hirsuta [83,99,104], T. multicolor [46,57,110], T. pubescens [63], T. suaveolens [63], T. versicolor [29,36,44,50,59,65,66,78,86,87,101,110], Trichaptum abietinu [63]; Schizophyllum commune [46,48,53,57]; "white-rot saprotrophic fungi, endemic to Alaska" [42] ably white rot Specified as "phylum Basidiomycetes" [24,40,51] As can be seen from Table 1, most studies on Mycelium-Based Composites conce white rot fungi. ...
... Various su strates are compared in scientific analyses or combined as mixtures in different propo tions. Combinations of various substrates in scientific experiments, described in 85 scie tific publications [21,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][40][41][42]45,46,[49][50][51][52][53][57][58][59][60][61][62][63][64][65][66][67][68]70,[72][73][74][75][76][77][78][79][80][81][82][83][84]111,112], are p sented in Figure 8. The size of the circle shows the popularity of the substrate and the lin indicate the most frequently used comparisons of substrates in scientific publications. ...
Article
Full-text available
Mycelium-Based Composites (MBCs) are innovative engineering materials made from lignocellulosic by-products bonded with fungal mycelium. While some performance characteristics of MBCs are inferior to those of currently used engineering materials, these composites nevertheless prove to be superior in ecological aspects. Improving the properties of MBCs may be achieved using an adequate substrate type, fungus species, and manufacturing technology. This article presents scientifically verified guiding principles for choosing a fungus species to obtain the desired effect. This aim was realized based on analyses of scientific articles concerning MBCs, mycological literature, and patent documents. Based on these analyses, over 70 fungi species used to manufacture MBC have been identified and the most commonly used combinations of fungi species-substrate-manufacturing technology are presented. The main result of this review was to demonstrate the characteristics of the fungi considered optimal in terms of the resulting engineering material properties. Thus, a list of the 11 main fungus characteristics that increase the effectiveness in the engineering material formation include: rapid hyphae growth, high virulence, dimitic or trimitic hyphal system, white rot decay type, high versatility in nutrition, high tolerance to a substrate, environmental parameters, susceptibility to readily controlled factors, easy to deactivate, saprophytic, non-mycotoxic, and capability to biosynthesize natural active substances. An additional analysis result is a list of the names of fungus species, the types of substrates used, the applications of the material produced, and the main findings reported in the scientific literature.
... There is a new trend that replaces the current chemical adhesives with bio-based adhesives to reduce the use of toxic materials in the automotive and building materials. This is because new furniture releases formaldehyde levels up to more than 0.3ppm and this causes health problems [19]. Mycelium can be used as green adhesive material instead of the synthetic adhesive in wood production. ...
... penetrate to form tight nets of cohesion and incoherent material within the SMS matrix which enhance the adhesive and bonding resulting in a strong bio-composite [19]. In addition, these thick mycelium layers also showed good water resistance properties. ...
... This ash can be used as a chemical activator to enhance the pozzolanic reactivity of pulverized fuel ash in the cement industry [20]. According to Khoo et al. [19] the SMS is used in the formulation of bioblocks, and during hot-compression process, the solid white mycelium melt and then penetrate to form tight nets of cohesion and incoherent material within the SMS matrix which enhance the adhesive and bonding resulting in a strong bio-composite. The SMS have also been used in manufacturing of biodegradable bioblocks which is done using a green synthesis approach and the mycelium as a natural adhesive material [22]. ...
... Soybean meal (SBM) as a widely sourced, environmentally friendly, and renewable biomass adhesive material has attracted much attention in recent years [7]. SBM has been widely studied in the area of plant protein adhesive, with the treatment reagents including enzyme [8], surfactants [9], urea [10], alkali [11], and epoxy resin [12]. The results showed that the dry shear strength (DSS) of SBM protein adhesive was close to that of formaldehyde adhesive, but the water resistance and wet shear strength (WSS) were poor due to large amounts of hydrophilic groups on the surface of soybean protein. ...
... 11Cracks on the surface of A1-pure HPMP, B1-SDS/HPMP, C1-SDS/nSiO2/HPMP, D1-HPMP, A2-pure SBMP, B2-SDS/SBMP, C2-SDS/nSiO2/SBMP, D2-SBMP, A3-pure CSMP, B3-SDS/CSMP, C3-SDS/nSiO2/CSMP, and D3-CSMP adhesives. ...
Article
Full-text available
Plant protein adhesive has received considerable attention because of their renewable raw material and no harmful substances such as formaldehyde. However, for the plant protein adhesive used in the field of plywood, low cost, strong water resistance, and high bonding strength were the necessary conditions for practical application. In this work, a double-network structure including hydrogen bonds and covalent bonds was built in hot-pressed peanut meal (HPM) protein (HPMP) adhesive, soybean meal (SBM) protein (SBMP) adhesive and cottonseed meal (CSM) protein (CSMP) adhesives. The ether bonds and ester bonds were the most in CSMP adhesive, followed by SBMP adhesive, while the hydrogen bond was the most in HPMP adhesive. The solubility of the HPMP, SBMP, and CSMP adhesives decreased by 14.3%, 24.2%, and 19.4%, the swelling rate decreased by 56.9%, 48.4%, and 78.5%, respectively. The boiling water strength (BWS) of HPMP (0.82 MPa), SBMP (0.92 MPa), and CSMP adhesives reached the bonding strength requirement of China National Standards class I plywood (type I, 0.7 MPa). The wet shear strength (WSS) of HPMP, SBMP, and CSMP adhesives increased by 334.5% (1.26 MPa), 246.3% (1.42 MPa), and 174.1% (1.59 MPa), respectively. This study provided a new theory and method for the development of eco-friendly plant meal protein adhesive and promotes the development of green adhesive.
... Over the years, natural fibre-based panels and other bio-composites have been attracting great attention of the scientific community and construction industry because of our increasing awareness of health and energy conservation and these biodegradable materials incorporating natural fibres present tremendous opportunities for growth and for further industry competitiveness in a world that is rapidly consuming many petroleum-based non-renewable resources at an ever-increasing rate [13][14][15][16]. The eco-friendly biocomposites can be easily disposed of or composted at the end of their life without harming the environment, which is not possible with synthetic fibre based polymer composites [17][18][19][20]. Many recent studies on this line have been reported including the novel idea of mycelium-based composites, an emerging category of bio-composites relying on the valorisation of lignocellulosic wastes and the natural growth of the living fungal organism. ...
Article
Full-text available
The concept of Ultra Low-Density Fibreboard (ULDF) from natural fibres was originated and advanced during the past few decades due to the need for a lightweight , better insulating and buffering material that could replace the synthetic materials like Styrofoam. Recently developed mycelium-based composites were considered as excellent replacements for such synthetic materials. However, one of the drawbacks of mycelium composites were the need for providing optimum conditions for the fungal growth. The present research work explored for the first time, a more practical way of producing ultra-low-density fibreboard by reinforcing the wood fibres with plant roots. As the plant root system grows, it absorbs moisture and the water which pass through the roots by capillary action to the shoots and the water is removed from the leaves due to transpiration. This process also binds together fibrous substrate materials and a biofibre reinforced system is produced in situ, offering great opportunities for the capillary action to the shoots and the water is removed from the leaves due to transpiration. This process also binds together fibrous substrate materials and a biofibre reinforced system is produced in situ, offering great opportunities for the development of fibreboard, utilising almost zero energy for drying of the substrate. Along with that, the work also experimented on the possibilities of creating moulded products using the same method. The boards produced were of lightweight and the production process eliminated the need of hot pressing or drying, thus being highly energy efficient. Nevertheless, the time taken for drying stands out to be a drawback of the process. The study being in its infancy has lot more to improve, together with the need of detailed tests on the physical and mechanical properties of the ULDF products.
... The contact angle of biocomposites was analyzed by the contact angle tester (DSA100S, KRUSS, Germany). During the experiment, a camera was used to record the shape and contact angles of water droplets staying on the surface of the samples at different time durations (0 s, 5 s, 10 s) (Khoo et al., 2020). Whether the sample is hydrophilic or hydrophobic was determined according to the ASTMD7334 standard. ...
Article
Green composite processing technology of wood fibers is an inevitable choice for global sustainable development. In this research, waste poplar powder with different particle sizes was used to prepare glue-free biocomposites with good mechanical and waterproof properties by hot-molding. The biocomposites made of larger size wood powder had better tensile strength (40.3 MPa) and the biocomposites made of smaller size wood powder had the greater bending strength (50.5 MPa). The thickness swelling rate of the biocomposites was only 4.26% after soaking in water for 24 h. The cross-section morphology of the biocomposites showed that the cell wall collapses enhanced the interfacial bonding. Chemical analysis showed that lignin repolymerized with cellulose and hemicellulose for the vitrification transition. In addition, the biocomposites with excellent mechanical properties had no formaldehyde release, which can replace the traditional density boards made of adhesives and applied as furniture materials and in line with the concept of cleaner production.
... For fiberboards, although fungal and enzymatic pretreatments were reported to decrease these values, all reported 24 h TS values were still much higher than the values required by ANSI standard. One exception is from a recently published paper (Khoo et al., 2020) where the 24 h TS of 160 • C hot-pressed fungal pretreated rubberwood sawdust was only 3.1%. This value is dramatically lower than the data obtained from other research groups. ...
Article
Full-text available
Fungal and enzymatic pre-treatments have long been used to activate the surface of lignocellulosic biomass particles or fibers to promote adhesion or develop novel composite materials and other products. Research into mycelium-based bio-composites, i.e. products in which constituents are bonded by fungal mycelium, is quite new and still growing. There has also been a significant amount of attention given to these materials by the industry and private sector. These bio-composites can be produced by enzymatically or fungally treating lignoicellulosic substrates and then either molding them into a shape and letting the fungus grow or, alternatively, by hot-pressing the substrate into a panel product. This review article focuses on hot-pressed, higherdensity lignocellulosic bio-composites produced following enzymatic or fungal pretreatment. The definitions, raw materials, processing procedures, material properties, factors governing product properties, and potential adhesion mechanisms are summarized and discussed. Finally, current commercial products are introduced and roadblocks in the way of further development are presented along with the identification of knowledge gaps.
... Last but not least, Khoo et al. (2020) recently published a new study involving the use of mushroom mycelium and substrate waste for the development of formaldehyde-free high-performance bio-board material. A thermocompression method was used to prepare different bio-panels. ...
Chapter
Most mushroom farming has been carried out using classical farming practices, giving one of the main reasons for low mushroom yield; in traditional mushroom farms routine practices are more labor intensive. Moreover, controlling insects, pests, and diseases is much more challenging and needs more vigilance. However, adapting innovative agricultural techniques can improve overall efficiency and productivity at a mushroom farm. One of the most advanced technologies is the application of the Internet of Things (IoT), which provides remote access to daily farm operations, and insect and pest control to the farmers. This sensor-based technique can be used to monitor crucial environmental factors including humidity, light, moisture, and temperature at a mushroom farm. The long-term benefits of semi- or fully automated farms result in high productivity, less labor, and reduced cost of production. Aside from the surrounding environmental conditions, controlling biotic stresses is also a challenging task at a mushroom farm. These may include insect pests, fungi, bacteria, nematodes, and some viral diseases. The use of synthetic chemical products at a mushroom farm can be hazardous to mushroom cultivation; thus, integrated pest management (IPM) and use of modern molecular approaches to confer natural resistance to biotic stresses can be effective control measures.
... They are the basis of many adhesives. A collaboration between plant biotechnology and environmental science research units in China, Malaysia and Denmark, led by Nyuk Ling Ma and Christian Sonne, has tested mycelium as a possible "green" adhesive substitute for the toxic urea-formaldehyde commonly used in particle board (Khoo et al., 2020). Rather than focusing on feeding regimes for living mycelium, as other researchers and manufacturers have done, this team has explored the potential of dead mushrooms, a growing waste product from the food industry. ...
Article
Full-text available
Architects, artists and engineers around the world have been experimenting with the potential of mycelium, the vegetative body of a fungus, as a future building material for the past 15 years. It shares many of the positive material attributes of polystyrene but unlike the synthetic material it is fully sustainable and completely biodegradable. Mycelium has also proved to be simple to grow at scale. Its capacity to rapidly grow its tangled hyphae in a multiplicity of directions, digesting nothing more than organic waste, has shown promise for the production of a variety of materials for the building industry. But despite this, mycelium has struggled to find a market within the building industry. Drawing on the literature, this article argues that the challenges have been psychological, aesthetic and economic, rather than technical. Western industrial systems have conditioned us to expect material cultures to be clean, precise and durable. Mycelium is messy and some fungi are known pathogens. Like any living creature it can be unpredictable. Further, while the materials for growing mycelium are cheap, initial production costs for mass production and distribution typical of industrial fabrication are high. The risk for investors in the absence of an assured market stymied early forays into production. But as the environmental crisis becomes more urgent, there is evidence of a growing interest in finding new avenues for production. Centralised large-scale production is only one way forward. Another, which learns from early failures, is mass production through a multiplicity of micro-scale, do-it-yourself systems.
... In this context it should also be pointed out that the spent mushroom substrate remaining after mushroom production is composed of mycelium and partly degraded substrate, and may have several applications that can benefit the development of a biobased society (Grimm and Wösten, 2018). Considering a spent substrate composed of sawdust, anaerobic digestate and mycelium, a potential use could be development of biomaterials as discussed by Khoo et al. (2020) or recirculating it back to the biogas process. ...
Article
Anaerobic digestion of organic waste results in production of biogas and a nutrient-rich digestate that has an established use as fertilizer in plant production. This study evaluated use of anaerobic digestate based on a high concentration of organic household waste as a fertilizer in sawdust-based production of oyster mushrooms (Pleurotus ostreatus). Inclusion of 0.5 L of anaerobic digestate (AD) per kg sawdust gave similar productivity in terms of biological efficiency (79.5 ± 5.4 %), and protein concentration (24.7 ± 2.4 % of dry weight (dw)) as standard mushroom substrate (78.1 ± 5.3 %, and 21.9 ± 3.0 % of dw, respectively). However, mushroom growth was impaired at the highest concentration of anaerobic digestate tested, 1 L digestate per kg dw sawdust. Comparison of the AD-fertilized substrate with a mushroom substrate with standard components (sawdust, wheat bran, calcium sulfate) and with similar C/N-ratio revealed some differences in elemental composition of the fruiting bodies, with an major increase in sodium concentration for the AD-fertilized substrate compared with the standard substrate (413.3 ± 28.9 and 226.7 ± 30.6 mg kg⁻¹ dw, respectively). This difference can be explained by high sodium concentration in the anaerobic digestate, most likely due to inclusion of food scraps from households and restaurants in the biodigester feedstock. Screening of both substrates for a total of 133 micropollutants revealed that total sum of micropollutants was significantly higher in the AD-fertilized substrate (258 ± 12 ng/g dw substrate) than in the standard substrate (191 ± 35 ng/g dw substrate). Nitrogen losses during preparation of the AD-fertilized substrate were negligible.
... The produced bio-board material from SMS of G. lucidum recorded the highest strength (2.51 mPa); high resistance to both fire and water [203] Discarded sticks of mushrooms MnO 2 -modifed biochar Antimony, Sb 100 mg L −1 in aqueous solution MnO 2 -modified biochar produced from discarded sticks of mushrooms was excellent adsorbent; adsorption capacity 64.12 mg g −1 [204] Abbreviations: nanoscale zero-valent iron (nZVI), palladium nanoparticles (Pd-NPs), Polycyclic aromatic hydrocarbons (PAHs), Spent mushroom substrate (SMS), weight/weight (w/w). ...
Article
Full-text available
Soil is the main component in the agroecosystem besides water, microbial communities, and cultivated plants. Several problems face soil, including soil pollution, erosion, salinization, and degradation on a global level. Many approaches have been applied to overcome these issues, such as phyto-, bio-, and nanoremediation through different soil management tools. Mushrooms can play a vital role in the soil through bio-nanoremediation, especially under the biological synthesis of nanoparticles, which could be used in the bioremediation process. This review focuses on the green synthesis of nanoparticles using mushrooms and the potential of bio-nanoremediation for polluted soils. The distinguished roles of mushrooms of soil improvement are considered a crucial dimension for sustainable soil management, which may include controlling soil erosion, improving soil aggregates, increasing soil organic matter content, enhancing the bioavailability of soil nutrients, and resorting to damaged and/or polluted soils. The field of bio-nanoremediation using mushrooms still requires further investigation, particularly regarding the sustainable management of soils.
... As layers, materials of synthetic and bio-based origin are suitable for mycelium composite formation, whereby the variety in the macro and nano range is almost unlimited. 15,16 Needleless electrospinning is a process in which polymer fibers with diameters in the range of ten to several hundred nanometers are produced. 17,18 In recent years, electrospinning has received increasing attention in scientific research and has found several technical applications. ...
Article
Full-text available
Mycelium-bound composites are new environmentally friendly, cost-effective and sustainable materials, enable energy-saving bio-composite fabrication, and provide an alternative to synthetic materials. Current research on mycelium-based composites reports on relatively coarse material compositions such as rice husks, cotton residues, sawdust, leaves and bio-waste, etc. According to research, very few publications report on mycelium-reinforced composites with the use of nanomaterials and this topic is under-researched and this study helps to fill this gap. The focus of this study deals with the preparation of mycelium-reinforced nanocomposites including nanofiber mats and the investigation of the different nanofiber mat morphologies on the growth of fungal mycelium. The mycelium macrofibers from Pleurotus ostreatus fungi were grown on polyacrylonitrile (PAN) nanofiber mats. Different morphologies of nanofiber mats such as fibrous and non-fibrous membrane areas or a mixture of both were used for mycelial growth with an additional nutrient. Moreover, mycelium/PAN nanocomposites were oxidative stabilized and carbonized and mycelium retains its morphology. For faster color differentiation between mycelium and nanofibers, PAN nanofiber mats were dyed in a one-step process by adding dye powder to the electrospinning solution as an additional tool. No significant differences in mycelial growth and morphology were observed regarding the different nanofiber mat types and the use of dye. These mycelium-reinforced nanocomposites are promising for many applications such as medicine and biotechnology, air and water purification and filtration, vertical farming, architecture, etc., and enable energy-saving bio-composite fabrication.
... The waterproof properties (hydrophilic or hydrophobic) of the biocomposites was then determined according to the ASTM D7334 standard. It was found that the surface of the biocomposites falls in the hydrophilic category where its contact angle was < 90 • [25]. ...
Article
There are abundant shrub species resources in the world, but their natural defects such as short growth cycle, loose material, easy cracking plus deformation, and low strength have seriously affected their scope of application. With the ever-decreasing of natural forest resources, the research on quality improvement and efficiency enhancement of small-diameter timber of artificial shrub represents a promising effort in global continual advancement. In this study, an innovative and environmentally-friendly approach was developed to produce high-quality biocomposites from Buxus sinica. Pretreatment of Buxus sinica in an alkaline sodium sulfite solution had degraded part of the amorphous structure from the cell walls. The fiber cell walls collapsed completely in further thermoforming, resulting in a closer alignment of the fiber filaments before the formation of high-strength physical and chemical bonding, expanded crystalline regions, and enhanced dimensional stability. The resulted biocomposites show higher ultimate tensile strength (5.31 times) and ultimate flexural strength (5.22 times) than that of Buxus sinica. In addition, the preparation method also endows the biocomposites with excellent hydrophobicity and high chemical stability towards concentrated strong acid and alkali. Overall, this study reveals a promising method to effectively transform the artificial shrub resources into high-quality biocomposites with versatile applications.
... For fiberboards, although fungal and enzymatic pretreatment were reported to decrease the values, all reported 24h TS values are still much higher than the ANSI standard. One exception is from a recently published paper (Khoo et al., 2020) where the 24h TS of 160 °C hot-pressed fungal pretreated rubberwood sawdust was only 3.1%. This value is dramatically lower than the data obtained from other research groups. ...
Article
The increasing environmental awareness has led to an increased interest in developing more sustainable materials as alternatives to petroleum-derived products. Among different nature-based products, fungal-mycelium-based bio-composites have gained considerable attention in various applications. Multiple materials with different densities and structures and potential applications can be fabricated by inoculating filamentous white-rot fungi in lignocellulosic materials and other substrates. Different from lower-density as-grown foam-like mycelium composites, higher-density mycelium-lignocellulosic panels have the potential to replace commercial particleboard and fiberboard bonded by petroleum-based resins. This kind of composite can be produced by directly adding heat and pressure to the low-density foams or by assembling mycelium-industry wastes before hot-pressing. The main goal of this dissertation was to investigate the principal adhesion mechanisms involved in the production of hot-pressed mycelium bio-composites. The functionality of surface mycelium for wood bonding was thoroughly investigated by growing Trametes versicolor on yellow birch veneers. The presence of surface mycelium improved the interface between two wood layers and consequently enhanced bonding. The surface mycelium layer was also confirmed to be able to be utilized as a stand-alone adhesive to bond untreated wood. The exopolysaccharides and proteins located at the interface between aerial mycelium and the substrate were confirmed to play an essential role in adhesion. The bonding mechanism and functionality of mycelium were also investigated in both as-grown and hot-pressed bio-composite structures. For low-density as-grown foam structures, fungal mycelium only worked as a binder, the lignocellulosic substrate material played an essential role in sound absorption and thermal insulation properties, and the denser mycelium structure had a negative effect on these properties. In a higher-density hot-pressed panel system, fungal mycelium contributed to bonding and reinforced the bio-composite by filling the gaps. Additionally, we also demonstrated that combining the advantages of nanocellulose research at UMaine into our novel mycelium bio-composite can provide further improvements in properties to manufacture formaldehyde-free hybrid composite panels. Finally, we discovered an all-natural mycelium surface with tunable wettability that can be switched several times from hydrophobic to hydrophilic status by a simple treatment. These surfaces can have potential applications in medical microfluidics and invisible pattern printing.
... In recent years, efforts toward the gradual reduction of fossil energy reliance and increasing attention to the ecological environment and human health (Khoo et al., 2020;Rosa et al., 2021;Shindell and Smith, 2019) necessitate research and the development of resource-saving and environment-friendly wood adhesives in the wood industry (Kristak et al., 2022;Stamenkovic et al., 2017;Ghahri et al., 2022). Soy protein-based adhesives have attracted broad interest from researchers because these adhesives are abundant in raw materials, environmentally friendly, and regenerative, among other advantages (Bai et al., 2021;Kim and Netravali, 2016). ...
Article
Full-text available
Epoxide modification effectively improves the water tolerance of soy protein adhesives, showing great potential in the commercial application as alternatives to petroleum-derived formaldehyde-based adhesives. However, epoxide-modified adhesives still present problematic limitations, such as poor mildew resistance and high hot-pressing temperature. In this study, a curing system based on radical polymerization was designed and developed to prepare soy protein adhesives, instead of building a traditional epoxide cross-linking structure. First, allyl glycidyl ether (G) was grafted onto a soy protein (SP) molecule to obtain soy protein with unsaturated double bonds (G@SP). Allicin (A) was then used as a cross-linker to build a cross-linking structure (G@SP/A) via free-radical polymerization to enhance the bond performance of the adhesive. Relative to that of pure SP adhesive, the wet shear strength (WSS) and dry shear strength (DSS) of plywood bonded with the G@SP/A adhesive increased by 108% and 45%, reaching 1.08 MPa and 1.84 MPa, respectively, at 120 • C pressing temperature. Notably, the G@SP/A adhesive showed superior antibacterial (Escherichia coli and Staphylococcus aureus) activity , high mildew resistance (35 d shelf life), good cytocompatibility, and biodegradability (30 d). Moreover, the WSS of plywood bonded with the G@SP/A adhesive at 80 • C for 6 min and 20 • C for 72 h reached 1.08 MPa and 1.12 MPa, respectively, indicating the sufficient low-temperature curing ability of the resultant adhesive. Thus, building a cross-linking structure by free-radical polymerization can be extended to improve the performance of film composites, other adhesives, and engineering materials.
... Throughout the testing, the contact angle of water droplets adhering to the sample surface at different times (i.e., 0, 5, and 10 s) was recorded, and the shape of a water droplet was captured by a high-resolution camera. 48 The surface and cross sections of the samples were observed using a Quanta 200 scanning electron microscope manufactured by FEI Company in the Netherlands at accelerated voltages of 10 and 15 kV at a magnification distance of 15 and 30 μm, respectively. 49 Thermogravimetric and derivative thermogravimetric curves were obtained from a TGA55 thermogravimetric analyzer manufactured by TA Instruments in the USA by heating 8 mg of sample powder from 30 to 650°C under a nitrogen environment at a heating rate of 10°C /min. ...
Article
Traditional wood-based panels are usually made from large-diameter trees and rely on adhesives for compactness, which negatively impacts the environment and human health. However, the widely distributed small-diameter shrubs are good raw materials for wood-based panels with abundant fibers, but are often under-exploited. This research reports the preparation of self-bonding biocomposites from Buxus sinica by an innovative combined approach of extraction, alkali treatment, and hot molding. The resulted biocomposites show better mechanical properties in which the flexural modulus (7.79 GPa) and the tensile modulus (4.33 GPa) were 5 times and 1.7 times higher than the conventional fiberboard, respectively, and also demonstrated better hydrophobicity than fiberboard, which could be due to the layer of lignin that formed on its surface preventing the infiltration of water. To sum up, the biocomposites prepared from small-diameter shrubs meet the requirement of the furniture and architectural decoration materials, suggesting that the proposed approach can be used to produce high-performance biocomposites.
Article
Full-text available
The most recent strategies available for upcycling agri-food losses and waste (FLW) into functional bioplastics and advanced materials are reviewed and the valorization of food residuals are put in perspective, adding to the water–food–energy nexus. Low value or underutilized biomass, biocolloids, water-soluble biopolymers, polymerizable monomers, and nutrients are introduced as feasible building blocks for biotechnological conversion into bioplastics. The latter are demonstrated for their incorporation in multifunctional packaging, biomedical devices, sensors, actuators, and energy conversion and storage devices, contributing to the valorization efforts within the future circular bioeconomy. Strategies are introduced to effectively synthesize, deconstruct and reassemble or engineer FLW-derived monomeric, polymeric, and colloidal building blocks. Multifunctional bioplastics are introduced considering the structural, chemical, physical as well as the accessibility of FLW precursors. Processing techniques are analyzed within the fields of polymer chemistry and physics. The prospects of FLW streams and biomass surplus, considering their availability, interactions with water and thermal stability, are critically discussed in a near-future scenario that is expected to lead to next-generation bioplastics and advanced materials.
Chapter
Fungi are efficiently used to produce a variety of medicinal compounds, functional foods, and environmentally sustainable raw materials for a wide range of consumer goods due to their distinctive biological properties. Mycelium, the vegetative structure of filamentous fungi, acts as a natural, self-assembling adhesive as it grows, binding the fragments of organic substrates, leading to the production of fungal mycelium-based biocomposites (MBCs). These biocomposites are biodegradable alternatives for many synthetic polymers, such as polystyrene, and are therefore considered as a widely applicable, emerging class of renewable materials. MBCs are excellent examples of circular materials, ensuring a cradle-to-cradle (C2C) design, in which biodegradable products can be returned to the ecosystem after its use. Diverse species of fungi can be used to produce MBCs together with a range of agricultural and other plant-based lignocellulosic substrates. Several business start-ups, by innovative investors, are globally leading in mycelium-based product manufacturing. MBCs, including both mycelium-based foams (MBFs) and mycelium-based sandwich composites (MBSCs), are known for their potential industrial applications, such as packaging materials, architectural design, construction, fashion, and automotive insulation products. Both the mycelium binder and substrate type have an immense impact on the significant material properties of MBCs, including their hydrophobicity, acoustic nature, thermal insulation, and fire resistance. This chapter summarizes the diversity of the fungi used to produce MBCs as well as their potential feeding substrates, manufacturing process, physical and mechanical properties, innovative applications, and future directions for related research endeavours.
Article
We analyzed the problematic textile fiber waste as potential precursor material to produce multilayer cotton fiber biocomposite. The properties of the products were better than the current dry bearing type particleboards and ordinary dry medium-density fiberboard in terms of the static bending strength (67.86 MPa), internal bonding strength (1.52 MPa) and water expansion rate (9.57%). The three-layer, four-layer and five-layer waste cotton fiber composite (WCFC) were tried in the experiment, the mechanical properties of the three-layer WCFC are insufficient, the five-layer WCFC is too thick and the four-layer WCFC had the best comprehensive performance. The cross-section morphology of the four-layer WCFC shows a dense structure with a high number of adhesives attached to the fiber. The hardness and stiffness of the four-layer cotton fiber composite enhanced by the high crystallinity of cellulose content, and several chemical bondings were presence in the composites. Minimum mass loss (30%) and thermal weight loss rate (0.70%/°C) was found for the four-layer WCFC. Overall, our findings suggested that the use of waste cotton fiber (WCF) to prepare biocomposite with desirable physical and chemical properties is feasible, and which can potentially be used as building material, furniture and automotive applications.
Article
Full-text available
Spent mushroom substrate (SMS) is lignocellulosic waste that contributes to environmental pollution. The entomogenous fungus Cordyceps militaris cannot utilize the cellulose in SMS for growth, but it can produce a series of bioactive compounds, including the FDA-approved first-line anticancer drug pentostatin. To efficiently utilize SMS, we engineered C. militaris to convert SMS into pentostatin. We optimized the composition ratio of a cellulase combination to obtain the best performance on SMS in vitro. The introduction of the optimized cellulase system in C. militaris led to strong hydrolytic activity towards cellulose, and the filter paper activity of one engineered strain, CmTX, reached 0.82 ± 0.02 U mL-1. The titer of pentostatin in CmTX under submerged fermentation with SMS as the substrate was 434.3 mg L-1, which was 2.32-fold that of the wild-type strain fermented in Sabouraud dextrose broth. CmTX under solid-state fermentation with SMS yielded 1.45 mg of pentostatin per gram of dried SMS. The production was further increased by 39.2% via a biasing metabolic flux from the cordycepin synthesis to pentostatin pathway. Although other strategies can produce pentostatin from glucose and other easily fermentable hexoses, the yield and titer of pentostatin in our engineered C. militaris strain with SMS as the substrate were 10-fold of those in previous reports. Compared with the chemical synthesis of pentostatin, our biological strategy overcomes the stereoselectivity of the chiral alcohol structure and glycoside groups during pentostatin synthesis. We successfully demonstrated that engineered C. militaris can produce valuable products using SMS as a substrate instead of a range of catalysts and complex chemicals, which enables green and sustainable SMS pollution removal while biosynthesizing a high-value anticancer drug.
Article
This study aimed to bioconvert of chitin waste biomass into oyster mushroom food and bioethanol through solid-state fermentation with Pleurotus ostreatus. The biological efficiency of the different recipes ranged from 75.66% to 130.61%. Three kinds of greenhouse gases (CO2, CH4, and N2O) were detected during oyster mushroom cultivation, whereas control group had 17.9% higher CO2 emissions than the shell waste-based formulas. The nutrient enrichment capability of fruiting bodies was demonstrated as follows: N (0.33)>P (0.24)>C (0.1). Among the four shell waste recipes, 50% crayfish shell and 50% chestnut hull were demonstrated to be optimal for the production of P. ostreatus mushrooms and bioethanol fuel. After solid state fermentation, the chitin-protein structure and calcium carbonate in shell waste were depolymerized and degraded and resulting in 24.53% higher than the initial substrate in enzymatic digestibility with chitinase. The highest total theoretical yield of ethanol was 7.72 ml/100 g and N-acetylglucosamine contributes 66.63%. This strategy could help divert excess nutrients in chitin waste biomass away from the environment into protein-rich oyster mushroom food and green biofuels production.
Article
The effect of carbon black from Mao bamboo (MBCB) as a reinforcing agent in melamine urea formaldehyde (MUF) resin wood adhesive is evaluated in this work. The incorporation of MBCB improved the adhesion strength and decreased the heat resistance of adhesive and the formaldehyde emission from plywood. Compared with MUF resin filled with flour, the wet bonding strength of that filled with MBCB was increased by 22.02% (from 1.68 to 2.05 MPa), and the formaldehyde emission was decreased by 21.24% (from 1.158 to 0.912 mg·L⁻¹). Unfortunately, with the increase in the substitution ratio of MBCB to flour, the pre-pressing performance of wood adhesives was reduced. The enthalpy was increased from 24.25 to 25.27 J·g⁻¹. It is suggested that MBCB participated in the curing process of MUF resin, which makes the curing reaction of MUF resin easier. Overall, these findings offer new insights into exploiting the utilization of carbon black in wood adhesives.
Article
Cadmium (Cd) is a toxic metal element that adversely affects water bodies and poses a threat to the ecological environment and human health. In this experiment, Pleurotus ostreatus spent substrate (P) was used as the initial material to prepare Pleurotus ostreatus spent substrate biochar (PB) at a high temperature of 500 °C, and then modified with CS2 and NaOH to obtain sulfur-modified Pleurotus ostreatus spent substrate (SP) and sulfur-modified Pleurotus ostreatus spent substrate biochar (SPB) to remove Cd(II) in aqueous solution. The adsorption of Cd(II) on the four materials follows the Langmuir isotherm model and the pseudo-second-order kinetic model. After modification with sulfur, the specific surface area and pore volume of both modified materials were significantly increased, and the adsorption capacity for cadmium was enhanced. The equilibrium adsorption capacity of SPB was 55.9636 mg g⁻¹, and the maximum adsorption capacity of SPB was 443%, 369% and 229% of that of P, SP and PB, respectively. Single factor batch adsorption experiments and characterization results showed that the adsorption of cadmium on SPB was mainly due to the interaction of cadmium and organic sulfides, the precipitation of cadmium hydroxide and carbonate, and the formation of Cd-Cπ bonds.
Article
The clean and eco-efficient utilization of agro-industrial lignocellulose wastes is imperative for social development. This study proposes a viable strategy combining rice straw and waste bamboo particles into bio-composites using green adhesives. These new bio-composites can displace the traditional wood-particle boards, which is a viable strategy to economize on wood resources. The internal bonding strength reached 0.57 MPa, and the thickness swelling rate was 7.00% (24h), which met the ISO requirements for P-FN MR1 particleboard in humid conditions. The characterizations of profile density distribution and microstructure were used to elucidate the mechanical strength and water resistance of bio-composites associated with the surface morphology of biomass and the density variation of bio-composites. The obtained green bio-composites can be utilized with long service life to realize carbon sequestration from agro-industrial lignocellulose wastes. According to the LCA, the net carbon flux could reach −1198.49 kg CO2 eq. when producing 1 m³ bio-composite. Meanwhile, if this strategy is successfully extended to the global particleboard market, the utilization of 23.97 million tonnes of rice straw per year can economize on 1.61 million hm² of the forest, and decrease the emission of CO2 by 63.76 million tonnes. This study provided a new straw/bamboo-based bio-composite. While using agro-industrial lignocellulose wastes efficiently, this new strategy can appreciably favour carbon neutrality.
Conference Paper
Full-text available
The aim of this research was to compare the chemical composition and other characteristics of two liquid organic fertilisers - biogas digestate and pig slurry. Variations in chemical composition of tested fertilisers might have been caused by the use of animal feeding stuffs in pig farms and their quality. Nitrogen is one of the main factors shaping both soil fertility and crop productivity. Ntot and N-NH4 concentrations were lower in anaerobic digestate rather than in pig slurry. Therefore, the use of digestate fertilisers may require more labour force and higher energy costs as a result of a higher fertilisation rate. The forms of digestate Corg had shown a high level of humification, which may have a positive impact on soil. Keywords: liquid anaerobic digestate, pig slurry, nutrients.
Article
Full-text available
Global solid waste is expected to increase by at least 70% annually until year 2050. The mixture of solid waste including food waste from food industry and domestic diaper waste in landfills is causing environmental and human health issues. Nevertheless, food and diaper waste containing high lignocellulose can easily degrade using lignocellulolytic enzymes thereby converted into energy for the development and growth of mushroom. Therefore, this study explores the potential of recycling biomass waste from coffee ground, banana, eggshell, tea waste, sugarcane bagasse and sawdust and diaper waste as raw material for Lingzhi mushroom (Ganoderma lucidum) cultivation. Using 2% of diaper core with sawdust biowaste leading to the fastest 100% mushroom mycelium spreading completed in one month. The highest production yield is 71.45 g mushroom; this represents about 36% production biological efficiency compared to only 21% as in commercial substrate. The high mushroom substrate reduction of 73% reflect the valorisation of landfill waste. The metabolomics profiling showed that the Lingzhi mushroom produced is of high quality with a high content of triterpene being the bioactive compounds that are medically important for treating assorted disease and used as health supplement. In conclusion, our study proposed a potential resource management towards zero-waste and circular bioeconomy for high profitable mushroom cultivation.
Article
Full-text available
This research work was aimed at comparing the properties of particleboards produced from sawdust with phenol formaldehyde and urea formaldehyde resins. The particleboards were produced using varied quantities of particle size 2mm. 30ml each of the resins which was prepared under same conditions, compression temperature of 180 0 C, pressure of 10tons, and pressing time of 15 minutes. The properties of the particleboards were tested and compared. The results showed that the particleboards produced with phenol formaldehyde had better properties compared to that of urea formaldehyde. And the property of the particleboards is a function of the percentage composition of the binder (resin) and the filler (sawdust).
Article
Full-text available
Abstract: Composite board made from palm sugar fiber (PSF) and cassava bagasse fiber (CB) bonded with biological adhesive from mycelium of Ganoderma lucidum was prepared. The composite boards were divided by varying the composition ratios of the PSF and CB (A = 65: 35; B = 50: 50; and C = 35: 65% w/w of composite board weight). The physical and mechanical properties of PSF/CB composite boards were carried out. The results showed that the moisture content, density, thickness swelling, and water absorption were 7.93 - 8.80%; 0.32 - 0.61/cm3; 13.5 - 18.00 %; and 64.22 - 116.96%, respectively. This study also revealed that the internal bond, modulus of rupture (MOR) and modulus of elasticity (MOE) were 0.03 - 0.76 MPa, 0.48 - 3.80 MPa, and 23.79 - 419.84 MPa, respectively. The Physical and mechanical properties of composite board fulfilled Japan Industrial Standard for particleboard. Hence, mycelium of Ganoderma lucidum could be used as a biological adhesive in composite board production.
Article
Full-text available
The first aim of the present study is to investigate the feasibility of the biogas production potential from Spent Mushroom Compost. Hence, its secondary aim is to study the replacement of this energy with the fossil energy source and its impact on the reduction of greenhouse gases emission. The production potential of biogas was evaluated in a laboratory-scale Open Outlet Flow Batch Type Anaerobic digester. Setups of biogas production were set at temperatures of 35°C and 55°C. Results indicate that the cumulative production of biogas at 55°C was more than that at 35°C (364.8 and 314.11 L/kg.VS, respectively). The energy required for 1 ton of spent mushroom compost in one period of production was 204.24–5.35T kW.h/ton. The amount of energy produced in a period of biogas production was calculated to be 277.95 kW.h/ton at 35°C and 322.84 kW.h/ton at 55°C. Results show that the total produced spent mushroom compost of the country is equal to 414,491.7 tons per year. Accordingly, the potential of methane production was calculated to be 8690.8 × 103 m³ per year. It can also reduce 0.02% of the total annual production of CO2 in Iran.
Article
Full-text available
The current physical goods economy produces materials by extracting finite valuable resources without taking their end of the life and environmental impact into account. Mycelium-based materials offer an alternative fabrication paradigm, based on the growth of materials rather than on extraction. Agricultural residue fibres are inoculated with fungal mycelium, which form an interwoven three-dimensional filamentous network binding the feedstock into a lightweight material. The mycelium-based material is heat-killed after the growing process. In this paper, we investigate the production process, the mechanical, physical and chemical properties of mycelium-based composites made with different types of lignocellulosic reinforcement fibres combined with a white rot fungus, Trametes versicolor. This is the first study reporting the dry density, the Young's modulus, the compressive stiffness, the stress-strain curves, the thermal conductivity, the water absorption rate and a FTIR analyse of mycelium-based composites by making use of a fully disclosed protocol with T. versicolor and five different type of fibres (hemp, flax, flax waste, softwood, straw) and fibre processings (loose, chopped, dust, pre-compressed and tow). The thermal conductivity and water absorption coefficient of the mycelium composites with flax, hemp, and straw have an overall good insulation behaviour in all the aspects compared to conventional materials such as rock wool, glass wool and extruded polystyrene. The conducted tests reveal that the mechanical performance of the mycelium-based composites depends more on the fibre processing (loose, chopped, pre-compressed, and tow), and size than on the chemical composition of the fibres. These experimental results show that mycelium-composites can fulfil the requirements of thermal insulation and have the potential to replace fosile-based composites. The methology used to evaluate the suitability and selection of organic waste-streams proved to be effective for the mycelium-material manufacturing applications.
Article
Full-text available
The mass of carbon contained in trees is governed by the volume and density of their wood. This represents a challenge to most remote sensing technologies, which typically detect surface structure and parameters related to wood volume but not to its density. Since wood density is largely determined by taxonomic identity this challenge is greatest in tropical forests where there are tens of thousands of tree species. Here, using pan-tropical literature and new analyses in Amazonia with plots with reliable identifications we assess the impact that species-related variation in wood density has on biomass estimates of mature tropical forests. We find impacts of species on forest biomass due to wood density at all scales from the individual tree up to the whole biome: variation in tree species composition regulates how much carbon forests can store. Even local differences in composition can cause variation in forest biomass and carbon density of 20% between subtly different local forest types, while additional large-scale floristic variation leads to variation in mean wood density of 10–30% across Amazonia and the tropics. Further, because species composition varies at all scales and even vertically within a stand, our analysis shows that bias and uncertainty always result if individual identity is ignored. Since sufficient inventory-based evidence based on botanical identification now exists to show that species composition matters biome-wide for biomass, we here assemble and provide mean basal-area-weighted wood density values for different forests across the lowand tropical biome. These range widely, from 0.467 to 0.728 g cm⁻³ with a pan-tropical mean of 0.619 g cm⁻³. Our analysis shows that mapping tropical ecosystem carbon always benefits from locally validated measurement of tree-by-tree botanical identity combined with tree-by-tree measurement of dimensions. Therefore whenever possible, efforts to map and monitor tropical forest carbon using remote sensing techniques should be combined with tree-level measurement of species identity by botanists working in inventory plots.
Article
Full-text available
This review is a summary of the Raman spectroscopy applications made over the last 10 years in the field of cellulose and lignocellulose materials. This paper functions as a status report on the kinds of information that can be generated by applying Raman spectroscopy. The information in the review is taken from the published papers and author’s own research—most of which is in print. Although, at the molecular level, focus of the investigations has been on cellulose and lignin, hemicelluloses have also received some attention. The progress over the last decade in applying Raman spectroscopy is a direct consequence of the technical advances in the field of Raman spectroscopy, in particular, the application of new Raman techniques (e.g., Raman imaging and coherent anti-Stokes Raman or CARS), novel ways of spectral analysis, and quantum chemical calculations. On the basis of this analysis, it is clear that Raman spectroscopy continues to play an important role in the field of cellulose and lignocellulose research across a wide range of areas and applications, and thereby provides useful information at the molecular level.
Article
Full-text available
Novel hybrid panel composites based on wood, fungal mycelium, and cellulose nanofibrils (CNF) were developed and investigated in the present study. In one set of experiments, mycelium was grown on softwood particles to produce mycelium-modified wood which was then hybridized with various levels of CNF as binder. The other set of experiments were conducted on unmodified wood particles mixed with CNF and pure mycelium tissue. It was found that the composites made of mycelium-modified wood and CNF resulted in enhanced physical and mechanical properties compared to the ones made by physically mixing wood, mycelium, and CNF. Scanning electron microscopy (SEM) images showed that mycelium modification covered wood particles with a network of fungal hyphae whereas CNF formed a uniform mycelial film over wood particles. Mycelium modification had a significant effect on reducing water absorption and thickness swelling of the hybrid composites and CNF increased the modulus of rupture and modulus of elasticity, optimally at 2.5% addition. We also present results and analysis pertaining to the development of unique lightweight composite systems with physical and mechanical properties optimized at 5% CNF addition with potential to be used in packaging and furniture applications.
Article
Full-text available
The disposal of used diapers is a critical eco-technological problem aggravated by the exponential increase of global consumption rate each year. The global production of disposable used diapers increases exponentially and is expected to exceed US$ 71 billion/year by 2022. It was revealed that about 20 billion pieces of the used diapers were dumped in landfills yearly, generating more than 3.5 million tonnes of diaper waste that require almost 500 years to be fully decomposed. The resource-consuming production and disposal of used diaper waste have led to many environmental issues and poses a threat to public health. This review provides an in-depth discussion of the challenges, strategies, and the recent breakthrough in rectifying problems arising from generation and disposal of used diapers. The use of various technologies for treatment and recycling of used diaper were highlighted, particularly on the use of potentially safer and cleaner technologies such as biodegradation and thermal pyrolysis in maximizing the recycling of used diapers with minimal cost. It was established that useful end products that have wide applications can be obtained through biodegradation and pyrolysis of used diapers, hence providing a future research direction to enhance the efficiency of these process in recycling of used diaper.
Article
Full-text available
Mycelium-based composites result from the growth of filamentous fungi on organic materials such as agricultural waste streams. These novel biomaterials represent a promising alternative for product design and manufacturing both in terms of sustainable manufacturing processes and circular lifespan. This study shows that their morphology, density, tensile and flexural strength, as well as their moisture- and water-uptake properties can be tuned by varying type of substrate (straw, sawdust, cotton), fungal species (Pleurotus ostreatus vs. Trametes multicolor) and processing technique (no pressing or cold or heat pressing). The fungal species impacts colonization level and the thickness of the air-exposed mycelium called fungal skin. Colonization level and skin thickness as well as the type of substrate determine the stiffness and water resistance of the materials. Moreover, it is shown that heat pressing improves homogeneity, strength and stiffness of the materials shifting their performance from foam-like to cork- and wood-like. Together, these results demonstrate that by changing the fabrication process, differences in performance of mycelium materials can be achieved. This highlights the possibility to produce a range of mycelium-based composites. In fact, it is the first time mycelium composites have been described with natural material properties.
Article
Full-text available
With the growing depletion of wood-based materials and concerns over emissions of formaldehyde from traditional wood fibre composites, there is a desire for environment- friendly binders. Herein, we report a green wood fibre composite with specific bonding strength and water resistance that is superior to a commercial system by using wood fibres and chitosan-based adhesives. When the mass ratio of solid content in the adhesive and absolute dry wood fibres was 3%, the bonding strength and water resistance of the wood fibre composite reached the optimal level, which was significantly improved over that of wood fibre composites without adhesive and completely met the requirements of the Chinese national standard GB/T 11718-2009. Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) characterizations revealed that the excellent performance of the binder might partly be due to the amide linkages and hydrogen bonding between wood fibres and the chitosan-based adhesive. We believe that this strategy could open new insights into the design of environment- friendlywood fibre compositeswith high bonding strength and water resistance for multifunctional applications.
Article
Full-text available
Synthetic structural materials with exceptional mechanical performance suffer from either large weight and adverse environmental impact (for example, steels and alloys) or complex manufacturing processes and thus high cost (for example, polymer-based and biomimetic composites)1,2,3,4,5,6,7,8. Natural wood is a low-cost and abundant material and has been used for millennia as a structural material for building and furniture construction9. However, the mechanical performance of natural wood (its strength and toughness) is unsatisfactory for many advanced engineering structures and applications. Pre-treatment with steam, heat, ammonia or cold rolling10,11,12,13,14,15,16,17,18,19,20,21 followed by densification has led to the enhanced mechanical performance of natural wood. However, the existing methods result in incomplete densification and lack dimensional stability, particularly in response to humid environments14, and wood treated in these ways can expand and weaken. Here we report a simple and effective strategy to transform bulk natural wood directly into a high-performance structural material with a more than tenfold increase in strength, toughness and ballistic resistance and with greater dimensional stability. Our two-step process involves the partial removal of lignin and hemicellulose from the natural wood via a boiling process in an aqueous mixture of NaOH and Na2SO3 followed by hot-pressing, leading to the total collapse of cell walls and the complete densification of the natural wood with highly aligned cellulose nanofibres. This strategy is shown to be universally effective for various species of wood. Our processed wood has a specific strength higher than that of most structural metals and alloys, making it a low-cost, high-performance, lightweight alternative.
Article
Full-text available
In this work, the adhesive systems used today in the European industries of particleboard, medium density fibreboard (MDF), and oriented strand board (OSB) are discussed. The structure of particleboard, MDF and OSB markets in Europe in relation to the types of adhesives and product specifications are presented as well. It is noticeable that new markets for wood-based panels like particleboard and fibreboard, known as non-furniture markets, are growing in Europe at a fast rate. It was concluded that most of the technological changes concerning the adhesive systems applied and additives have been realised from the need for niche panel products, the obligation to reach even lower formaldehyde emissions, and the necessity to decrease production costs due to the stringent competition in the market of wood-based panels
Article
Full-text available
Lignin is an abundant polyphenol biopolymeric material. Lignin was phosphorylated thanks to the presence of reactive hydroxyl groups in its structure. A detailed characterization allowed us to prove that phosphate groups are covalently bonded to the lignin's structure. The thermal stability of lignin was improved with the presence of phosphorus and was evaluated at 3% w/w. The thermal decomposition of lignin was deeply investigated through gas and condensed phases analyzes. The phosphorus was found to promote dehydration and decarboxylation reactions, thus increasing the amount of carbonaceous residue which was more stable at high temperature. The combustibility of lignin was also lowered when phosphorylated. Finally, even if half of the initial amount was released in the gas phase, the phosphorus mainly acts in the condensed phase by forming different species, which prevents the residue from oxidation.
Article
Full-text available
Toxic formaldehyde is sometimes used illegally as a food preservative, however, on-site rapid analysis of trace formaldehyde in aquatic products remains a challenge. In this work, a simple on-site rapid quantification method for trace volatile formaldehyde in aquatic products was developed by a derivative reaction-based surface enhanced Raman spectroscopy (SERS) technique coupled with a homemade portable purge-sampling device. Trace formaldehyde separated from complicated aquatic matrices via a purge-sampling procedure was reacted with a derivative reagent to produce a Raman-active analyte for consequent SERS analysis. Au/SiO2 nanoparticles (NPs) were employed as the enhancement substrate to achieve significant enhancement of Raman signal intensity. Conditions of derivative reaction and SERS detection were optimized in detail, and the selectivity of this analytical method was also evaluated based on related analogs. Under optimal conditions, an extremely low detection limit of 0.17 μg L(-1) was achieved. Trace volatile formaldehyde can be found in fresh squid and shrimp samples without obvious matrix interference, and this was quantified to be 0.13-0.21 mg kg(-1) using the described method. The recoveries of spiked aquatic product samples were found to be 70.0-89.1% with RSDs of 2.3-7.2% (n = 3). The results suggest that the proposed method is reliable and suitable for on-site rapid analysis of trace formaldehyde in aquatic products.
Article
Full-text available
Wood is known to contain and emit volatile organic compounds including formaldehyde. The emission of formaldehyde from wood increases during its processing to lumber and wood-based panels (i.e., particleboard and fiberboard). This increased emission can be attributed to the processing procedure of wood, which includes drying, pressing, and thermo-hydrolysis. Formaldehyde is emitted from wood under very high heat and is not expected to be a significant source of the emissions from composite wood products during normal service. Formaldehyde is also detectable even if wood has never been heated as well as under more or less ambient conditions. The presence of formaldehyde in the emissions from wood that does not contain adhesive resin has been explained by thermal degradation of polysaccharides in the wood. The emission levels of formaldehyde depend on factors such as wood species, moisture content, outside temperature, and time of storage. Additionally, the pyrolysis of milled wood lignin at 450 °C yields benzaldehyde, and the pyrolysis of spruce and pinewood at 450 °C generate formaldehyde, acetaldehyde, 2–propenal, butanal, and butanone, which can be attributed to the breakdown of the polysaccharide fraction of the wood.
Article
Full-text available
In recent times, increasing attention has been paid to the use of renewable resources particularly of plant origin keeping in view the ecological concerns, renewability and many governments passing laws for the use of such materials. On the other hand, despite abundant availability of lignocellulosic materials in Brazil, very few attempts have been made about their utilization, probably due to lack of sufficient structure/property data. Systematic studies to know their properties and morphology may bridge this gap while leading to value addition to these natural materials. Chemical composition, X-ray powder diffraction, and morphological studies and thermal behavior aspects in respect of banana, sugarcane bagasse sponge gourd fibers of Brazilian origin are presented. Chemical compositions of the three fibers are found to be different than those reported earlier. X-ray diffraction patterns of these three fibers exhibit mainly cellulose type I structure with the crystallinity indices of 39%, 48% and 50% respectively for these fibers. Morphological studies of the fibers revealed different sizes and arrangement of cells. Thermal stability of all the fibers is found to be around 200 °C. Decomposition of both cellulose and hemicelluloses in the fibers takes place at 300 °C and above, while the degradation of fibers takes place above 400 °C. These data may help finding new uses for these fibers.
Article
Full-text available
Two new methods based on FT–Raman spectroscopy, one simple, based on band intensity ratio, and the other using a partial least squares (PLS) regression model, are proposed to determine cellulose I crystallinity. In the simple method, crystallinity in cellulose I samples was determined based on univariate regression that was first developed using the Raman band intensity ratio of the 380 and 1,096cm−1 bands. For calibration purposes, 80.5% crystalline and 120-min milled (0% crystalline) Whatman CC31 and six cellulose mixtures produced with crystallinities in the range 10.9–64% were used. When intensity ratios were plotted against crystallinities of the calibration set samples, the plot showed a linear correlation (coefficient of determination R 2=0.992). Average standard error calculated from replicate Raman acquisitions indicated that the cellulose Raman crystallinity model was reliable. Crystallinities of the cellulose mixtures samples were also calculated from X-ray diffractograms using the amorphous contribution subtraction (Segal) method and it was found that the Raman model was better. Additionally, using both Raman and X-ray techniques, sample crystallinities were determined from partially crystalline cellulose samples that were generated by grinding Whatman CC31 in a vibratory mill. The two techniques showed significant differences. In the second approach, successful Raman PLS regression models for crystallinity, covering the 0–80.5% range, were generated from the ten calibration set Raman spectra. Both univariate-Raman and WAXS determined crystallinities were used as references. The calibration models had strong relationships between determined and predicted crystallinity values (R 2=0.998 and 0.984, for univariate-Raman and WAXS referenced models, respectively). Compared to WAXS, univariate-Raman referenced model was found to be better (root mean square error of calibration (RMSEC) and root mean square error of prediction (RMSEP) values of 6.1 and 7.9% vs. 1.8 and 3.3%, respectively). It was concluded that either of the two Raman methods could be used for cellulose I crystallinity determination in cellulose samples. KeywordsCellulose-Crystallinity-Raman spectroscopy-FT–Raman-Univariate-Multivariate-PLS-X-ray
Article
Full-text available
Increasing worldwide environmental awareness is encouraging scientific research into developing cheaper, more sustainable materials. Industrial hemp fiber is one of the strongest and stiffest available natural fibers [K. L. Pickering, M. Priest, T. Watts, G. Beckermann, and S. N. Alam, J. Adv. Mater. 37, 15 (2005)] and therefore has great potential in composite materials. Incorporated into a thermoplastic matrix, it gives a structural material that is cheap, lightweight, and recyclable. However, natural fibers are commonly incompatible with common molding thermoplastics such as polypropylene, which limits the performance of the composites produced. The main objective of the current work was to investigate the use of fungi to treat hemp fiber to create better bonding characteristics in natural fiber reinforced polypropylene composites. X-ray diffraction (XRD), ζ-potential, lignin testing, thermal analysis, and scanning electron microscopy (SEM) were used to characterize the effect of treatment on hemp fibers. A combined alkali and fungi treated fiber composite produced the highest tensile strength of 48.3 MPa, an increase of 32% compared to composites with untreated fiber.
Article
Full-text available
Thin films of formaldehyde-water mixtures are co-deposited at 88 K and 10(-1) Torr from gas collected above formaldehyde aqueous solutions of different concentrations (5, 10, 15, 20, 30 mol%). They are analyzed in situ by micro-Raman scattering in the 2700-3800 cm(-1) spectral range. The spectral characteristic of H2CO distributed molecularly in amorphous solid water is obtained under vacuum conditions. As temperature is increased formaldehyde is released during the crystallization of ice between 118 and 138 K. On the other hand, under controlled nitrogen atmosphere, the deposits crystallize in hydrate phases (or solid H2CO(s)) during annealing. A new phase (metastable FOR-A) of H2CO(s) (or a low hydrate after rejection by crystallizing ice) can be spectroscopically identified at 138 K before transformation into a hydrate (with molecular H2CO distributed within the cages of the clathrate FOR-B) takes place at 148 K. This latter phase decomposes between ca. 180 and 200 K. The significant spectral differences between these hydrates and those formed in frozen formaldehyde aqueous solutions reflect the existence of H2CO-clusters of distinctive structural nature relative to those resulting from important oligomerization process in the liquid. Moreover, the structure, the gas distribution and relative gas population in the formaldehyde clathrate cages are influenced by the relative amount of trapped nitrogen at the surface, which moreover depends on the ice film morphology. The dependence on the crystallization temperature of the deposits is explained by the relative amounts of occluded H2CO/N2 and the external pressure conditions. The distinct behavior observed between vacuum and N2-atmosphere conditions certainly reflects a complex mechanism of surface mediated nucleation in which the transport of the reactants to the hydrate reaction zone is facilitated by the presence of a polar dopant.
Article
Full-text available
This study was carried out to test the potentially of using rice straw substrate for the cultivation of four Pleurotus species including Pleurotus florida, Pleurotus djamor, Pleurotus sajor-caju and Pleurotus ostreatus and the effect of these species on the chemical composition, cell wall degradation and digestibility of rice straw. Rice straw soaked in water for 24 h and then it was pasteurized at 100 degrees C for 6 h. Rice straw was inoculated with spawns of four Pleurotus fungi (Pleurotus florida, Pleurotus djamor, Pleurotus sajor-caju and Pleurotus ostreatus) and packed in the plastic bags and incubated in a fermentation chamber at 23-27 degrees C and 75-85% relative humidity. After 60th day, rice straw samples from all groups were taken and analyzed for chemical composition and in vitro digestibility. The data obtained were analyzed according to the complete randomized design model consisting of four treatments plus one control and four replicates. The results of this study showed that fungal treatment increased (p<0.05) the Crude Protein (CP), silica, Ca and P contents of the rice straw but the hemicellulose, Organic Matter (OM), Acid Detergent Fiber (ADF), Neutral Detergent Fiber (NDF) and Acid Detergent Lignin (ADL) contents decreased. However, the ability of the fungi to degrade these components varied among the species. The ability of Pleurotus sajor-caju and Pleurotus ostreatus were higher than the other species in decreasing the hemicellulose, NDF, ADF and ADL contents. The highest Biological Efficiency (BE) was produced by sajor-caju species with 56.02 and the lowest was belong to Pleurotus djamor species with an average 51.17%. All species of fungi incubated on rice straw showed increased (p<0.05) the in vitro dry mater and organic matter digestibility. Rice straw treated with sajor-caju fungus had the highest in vitro dry matter digestibility (IVDMD) and in vitro organic matter digestibility (IVOMD) with 80.10 and 82.18%, respectively. In general this experiment cleared that treatment with sajor-caju can improve the quality of rice straw to be useful feed for ruminant nutrition.
Article
Used baby diaper consists of a combination of decomposable cellulose, non-biodegradable plastic materials (e.g. polyolefins) and super-absorbent polymer materials, thus making it difficult to be sorted and separated for recycling. Microwave pyrolysis was examined for its potential as an approach to transform used baby diapers into value-added products. Influence of the key operating parameters comprising process temperature and microwave power were investigated. The pyrolysis showed a rapid heating process (up to 43 °C/min of heating rate) and quick reaction time (20–40 min) in valorizing the used diapers to generate pyrolysis products comprising up to 43 wt% production of liquid oil, 29 wt% gases and 28 wt% char product. Microwave power and operating temperature were observed to have impacts on the heating rate, process time, production and characteristics of the liquid oil and solid char. The liquid oil contained alkanes, alkenes and esters that can potentially be used as chemical additives, cosmetic products and fuel. The solid char contained high carbon, low nitrogen and free of sulphur, thus showing potential for use as adsorbents and soil additives. These observations demonstrate that microwave pyrolysis has great prospect in transforming used baby diaper into liquid oil and char products that can be utilised in several applications.
Article
BACKGROUND Spent mushroom substrate (SMS), largely produced as an agriculture waste from mushroom cultivation, was transformed into biochar via microwave vacuum pyrolysis under different ratios of SMS to microwave absorbent (1:1, 1:2, and 1:3). The biochar was then examined for its potential to be re‐used in mushroom cultivation as a growth medium added to conventional mushroom baglog (plastic bag with mushroom seeds and culture substrates containing rice straw, sawdust, lime and water), with emphasis on its ability to form mycelium – a fungus that grows into mushroom from its seeds. RESULT The pyrolysis generated up to 36 wt% biochar yield with a large adsorption area (up to 215 m²/g) and less water percentage (4 wt%), indicating that many adsorption sites are available on which mushroom seeds, nutrient and water can be adsorbed onto in order to form mycelium (and subsequently mushroom). The biochar added to grow mushroom in baglog recorded a higher water retention percentage (up to 59%), a higher mycelium colonization length in 8 days (6.3 cm), coverage area (up to 259 cm²) and total mycelium growth volume (317 cm³), and resulted in a higher yield of mushroom (200 g/month) than that recorded in the conventional baglog without biochar (160 g/month). CONCLUSION The results indicated that biochar produced from SMS using microwave vacuum pyrolysis shows great potential in retaining water and nutrient that in turn promotes the formation of mycelium that leads to increased growth of mushroom in its cultivation. This article is protected by copyright. All rights reserved.
Article
Formaldehyde, HCHO, is one of the most common toxic pollutants found in indoor air. Its most common sources are pressed woods and particle boards. National Toxicology Program of Department of Health and Human Services classifies formaldehyde as human carcinogen and its exposure limit is 0.08 ppm for 30 min. So far, besides room venting, no other means have been recommended by Consumer Products Safety Commission to minimize indoor HCHO exposure. Since adsorption seems to be an efficient and cost-effective method of HCHO removal, in this review we summarize the findings on the applications of carbonaceous materials (mainly activated carbons, carbon fibers and their composites with an inorganic phase) as formaldehyde adsorbents from indoor air. Besides experiments, recent theoretical and simulation results are also discussed. Our intention is to use them as a basis for a further development of the next generation of efficient and cost-effective carbon-based reactive adsorbents where adsorption of HCOH will be combined with its mineralization at ambient conditions.
Article
Microwave vacuum pyrolysis of palm kernel shell (PKS) was performed to produce biochar, which was then tested as bio-fertilizer in growing Oyster mushroom (Pleurotus ostreatus). The pyrolysis approach produced biochar containing a highly porous structure with a high BET surface area of up to 270 m2/g and low moisture content (≤10 wt%), exhibiting desirable adsorption properties to be used as bio-fertilizer since it can act as a housing that provides many sites on which living microorganisms (mycelium or plant-growth promoting bacteria) and organic nutrients can be attached or adsorbed onto. This could in turn stimulate plant growth by increasing the availability and supply of nutrients to the targeted host plant. The results from growing Oyster mushroom using the biochar recorded an impressive growth rate and a monthly production of up to about 550 g of mushroom. A shorter time for mycelium growth on one whole baglog (21 days) and the highest yield of Oyster mushroom (550 g) were obtained from cultivation medium added with 20 g of biochar. Our results demonstrate that the biochar-based bio-fertilizer produced from microwave vacuum pyrolysis of PKS shows exceptional promise as growth promoting material for mushroom cultivation.
Article
The aim of the present work is to develop processes for the production of bio-oil and bio-char from algae waste using the pyrolysis at controlled conditions. The pyrolysis was carried out at different temperatures 400-600 °C and different heating rates 5-50 °C/min. The algal waste, bio-oil and bio-char were successfully characterized using Elemental analysis, Chemical composition, TGA, FTIR, ¹H-NMR, GC-MS and SEM. At a temperature of 500 °C and a heating rate of 10 °C/min, the maximum yield of bio-oil and bio-char was found to be 24.10 and 44.01wt%, respectively, which was found to be strongly influenced by the temperature variation, and weakly affected by the heating rate variation. Results show that the bio-oil cannot be used as bio-fuel, but can be used as a source of value-added chemicals. On the other hand, the bio-char is a promising candidate for solid fuel applications and for the production of carbon materials.
Article
This study aimed at developing a biocomposite using polypropylene (PP) as the matrix andArgan nut shell (ANS) as reinforcement. Also,styrene-(ethylene-butene)-styrene triblock copolymer grafted with maleic anhydride (SEBS-g-MA) was used as a coupling agent. The samples were prepared by using extrusion compounding followed by injection molding to determine the effect of filler and coupling agent content on the morphological, thermal, mechanical, andhygroscopic properties of the biocomposites. SEM micrographs revealed thatgood ANS dispersion/distribution into PP was achieved with an important reduction of fiber pull-out, micro-spaces, and voids with coupling agent addition. This led to substantial improvement intension, torsion, and water absorptionreduction due to improved interfacial adhesion. Although ANS particles did not significantly modify the thermal stability of PP, the use of a coupling agent increased it. The experimental data were compared with several theoretical models such Voigt, Reuss, Hirsch, and Tsai-Pagano to characterize the interfacial adhesion quality and to determine the elastic modulus of a single ANS particle.Finally, all the results show that Argan waste to produce PP biocomposites is an interesting avenue to effectively deal with agricultural wastes and develop valuable industrial and practical applications.
Article
Bio-composite which is made of wood sawdust (SW) with novel modification and gypsum is presented in this paper. Attenuated total reflectance-fourier transform infrared (ATR-FTIR) characterizations reveal that the main compositions of sawdust water extractives are tannins, acetic acid, hemicellulose, and lignin. Positive effect of sawdust water extractives on gypsum was achieved by the addition of antifoam agent. Mechanical testing shows that the mechanism of sawdust induced reduction of gypsum performance may be attributed to the water absorption of sawdust. Subtraction and matching analysis with OMNIC software indicates that water-based epoxy (WEP) could be coated on the surface of sawdust by using spray coating, which resulted in a reduction of the water absorption of sawdust up to 25.6% and water content inside gypsum/sawdust composite up to 35.8%. Mechanical testing of gypsum/sawdust composite shows that the light weight composite with promising mechanical performance could be obtained by the WEP treatment: for 20% sawdust addition, the flexural strength and compressive strength of composite are 4.59 MPa and 13.25 MPa, respectively; for 30% sawdust addition, the flexural strength and compressive strength of composite are 3.36 MPa and 8.73 MPa, respectively.
Article
Chars were obtained from spent mushroom substrate (SMS) via pyrolysis. It was found that as the pyrolysis temperature increased from 400 to 700 °C, the char yield decreased from 45.10 to 33.79 wt.% and the higher heating value increased from 17.32 to 22.72 MJ/kg. The largest BET surface area (13 m2/g) was created at 500 °C. Hydrogen atoms were continuously lost during pyrolysis, whereas oxygen atoms were difficult to eliminate. Whewellite, calcite, lime, and quartz were the minerals in the chars, and their forms and crystallinity changed with changing pyrolysis temperature. Activated carbon with a BET surface area of 1023 m2/g and a total pore volume of 0.595 cm3/g was obtained from the char prepared at 500 °C. Its characteristics were studied by N2-adsorption, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The pyrolysis and KOH-activation processes were investigated by thermogravimetric analysis (TGA). The results showed that the pyrolysis of SMS occurred primarily between 217 and 375 °C and that the energies needed for the pyrolysis reactions were relatively low due to the prior mushroom cultivation. Furthermore, lignin was incompletely decomposed in the char prepared at 500 °C, and KOH suppressed tar evolution and reduced the energy needed to decompose the residual lignin during activation.
Article
Cellulose allomorphs were prepared and carefully characterized.•Measurements by oxygen bomb calorimetry, solution calorimetry, and by PPMS.•Thermodynamic properties for interconversion reactions of the cellulose allomorphs.•Review of the earlier literature with recalculation of property values.•Standard thermodynamic formation properties.
Article
Moisture absorption and dimensional distortion are the major drawbacks of wood utilization as building material. In this study, poplar wood coated with a thin layer of titanium diox­ ide (TiO 2) was prepared by the cosolvent-controlled hydro­ thermal method. Subsequently, its moisture absorption and dimensional stability were examined. Scanning electron microscopy analysis revealed that the wood substrate was closely and entirely covered with the TiO 2 coat. Microscale features were visible despite masking of the ultrastructural features of the cell wall. To explore the effects of TiO 2 coat­ ing on the water-repellency and dimensional stability of wood, a 90-day water immersion test was carried out. Results showed that water absorption and thickness swelling of TiO 2 ­ coated wood increase very slowly and minimally. Weight change after 90 days of water immersion was reduced to 20.5%, nearly one-tenth of untreated control wood, and that maximum cross-sectional relative swelling was only 1.2%. Specimens were conditioned for 3 months at 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% relative humidity (RH) to determine the effects of RH on moisture absorption and dimensional swelling of TiO 2 -coated wood. There was no change in weight after 3 months of being exposed to humid­ ity conditions below 60%, whereas there was linear weight increase above 60% RH, but the maximum change was less than 6%. Cross-sectional relative swelling was less than 0.3% below 60% RH but increased as RH exceeded 60%. The maximum change was approximately 3%. Anisotropic thickness swelling of wood was almost eliminated after coat­ ing. It is obvious that TiO 2 coating can act as a moisture barrier for wood and is an exceptionally strong water vapor-inhibiting shield under very humid conditions.
Article
The addition of small percentages of Na+-montmorillonite (NaMMT) nanoclay does not appear to improve much the performance of thermosetting phenol-formaldehyde (PF) and phenol-urea-formaldehyde (PUF) resins used as adhesives for plywood and for wood particleboard. X-ray diffraction (XRD) studies indicated that NaMMT does not become completely exfoliated when mixed in small proportions to PF resins, contrary to that observed for acid-setting urea-formaldehyde (UF) resins. Differential scanning calorimetry (DSC) indicated that NaMMT has no accelerating effect on the curing of alkaline PF resins, contrary to that observed for UF resins.
Article
This paper provides a comprehensive overview on different surface treatments applied to natural fibres for advanced composites applications. In practice, the major drawbacks of using natural fibres are their high degree of moisture absorption and poor dimensional stability. The primary objective of surface treatments on natural fibres is to maximize the bonding strength so as the stress transferability in the composites. The overall mechanical properties of natural fibre reinforced polymer composites are highly dependent on the morphology, aspect ratio, hydrophilic tendency and dimensional stability of the fibres used. The effects of different chemical treatments on cellulosic fibres that are used as reinforcements for thermoset and thermoplastics are studied. The chemical sources for the treatments include alkali, silane, acetylation, benzoylation, acrylation and acrylonitrile grafting, maleated coupling agents, permanganate, peroxide, isocyanate, stearic acid, sodium chlorite, triazine, fatty acid derivate (oleoyl chloride) and fungal. The significance of chemically-treated natural fibres is seen through the improvement of mechanical strength and dimensional stability of resultant composites as compared with a pristine sample.
Article
Short untreated and white rot fungi treated hemp fibre, polypropylene (PP) and maleated polypropylene (MAPP) coupling agent were extruded and injection moulded into composite tensile test specimens. The tensile properties of untreated and treated fibre and their composites were measured. The fibre length distributions in the composite were obtained by dissolving the PP/MAPP matrix in boiling xylene to extract the fibre. Both the Single Fibre Pull-Out test and the Bowyer and Bader model were used to determine the interfacial shear strength (IFSS) of these composites. IFSS was found to be lower for the Single Fibre Pull-Out test, which was considered to be largely due to axial loading of fibre and the resulting Poisson’s contraction occurring during this technique. This suggests that the Bowyer and Bader model provides a more relevant value of IFSS for composites. The results obtained from both methods showed that IFSS of the treated fibre composites was higher than that for untreated fibre composites. This supports that the hemp fibre interfacial bonding with PP was improved by white rot fungi treatment.
Article
Reinforced thermoplastics generally are produced by incorporation of reinforcement agents or fillers into thermoplastic resins. The utilization of lignocellulosic material as filler with reinforcement in polymer matrix has received much interest due to its lower price and other properties. A composite of polystyrene reinforced with oil palm empty fruit bunches (EFB) and chemically treated EFB with benzoyl chloride (EFB-benzoylated) as a function of loading and fiber surface modification were prepared. The chemically treated fibers were analyzed with FT-IR to observe the extent of chemical reaction with EFB fiber. The sharp peak at 710 cm−1 appeared on the spectra, which indicated that the mono-substituted benzene ring has taken place. The strong peak at 1720 cm−1 has indicated the presence of ester group treated fiber. The flexural test was performed using Instron 4301 testing machine to study flexural properties of the composites with various fiber sizes. The results showed that the flexural properties increased with particle size. The flexural strength of EFB-benzoylated composites was observed to be stronger than untreated EFB fiber. Scanning electron microscope was used to investigate the morphological structure of the fiber surface, fiber pull out, fracture surface, and fiber–matrix interface. The untreated EFB composites showed hole and fiber end, which indicated that most of the fiber have pulled out breaking during the fracture of composites; however, the treated EFB-benzoylated showed a good adhesion between fiber and matrix.
Chapter
Wood-based panels have become an important component in the wood processing chain. From a materials viewpoint wood-based panels provide a way of realizing value from materials that are not suitable for other uses, or that are residue streams from other processes. However these panels are now an integral part of the wood products market, meeting requirements that were once met by solid wood. The ability to produce panels of larger sizes reduces the number of components needed while the uniformity of panel properties give a more consistent performance. The panels are used extensively in construction and in the furniture, cabinet and joinery industries, while the ability to engineer these products to meet specific performance requirements has been a significant factor in their growth. The technology for producing these panels has developed significantly, in particular with the introduction of continuous pressing providing new levels of product uniformity.
Article
The effect of intermittent heat treatment on cellulose crystallites in wood was studied to evaluate quantitatively the changes of crystallinity induced by intermittent and continuous heating. The changes in crystallinity were found to be strongly affected by the intermittent heat treatment. The increased crystallinity, the width of the crystals, and the piezoelectric properties were the same for the first intermittent heating as for continuous heating. Further intermittent heating for the same time duration and temperature had no effect on the above properties, probably due to the stopping of the thermal reaction during the interval. Our results suggested that intermittent heat treatment has certain critical cooling temperatures that stop the thermal reaction and are closely related to the duration of the interval. Samples once exposed to a certain duration of heat treatment and then cooled need more time, about twice that of the first duration of intermittent heating compared with continuous heating, to reach maximum crystallinity in wood cellulose.
Article
It is well known that the roughness of a hydrophobic solid enhances its hydrophobicity. The contact angle of water on such flat solids is typically of the order of 100 to 120 degrees, but reaches values as high as 160 to 175 degrees if they are rough or microtextured. This result is remarkable because such behaviour cannot be generated by surface chemistry alone. Two distinct hypotheses are classically proposed to explain this effect. On one hand, roughness increases the surface area of the solid, which geometrically enhances hydrophobicity (Wenzel model). On the other hand, air can remain trapped below the drop, which also leads to a superhydrophobic behaviour, because the drop sits partially on air (Cassie model). However, it is shown here that both situations are very different from their adhesive properties, because Wenzel drops are found to be highly pinned. In addition, irreversible transitions can be induced between Cassie and Wenzel states, with a loss of the anti-adhesive properties generally associated with superhydrophobicity.
Article
Spent mushroom compost (SMC) is a bulky waste byproduct of mushroom industry and produced abundantly. The SMC of Pleurotus pulmonarius immobilized laccase (0.88 mmoles min(-1) g(-1)) and manganese peroxidase (0.58 mmoles min(-1) g(-1)) of which the optimal temperatures were 45 and 75 degrees C, respectively. In laboratory test, complete degradative removal of individual naphthalene, phenanthrene, benzo[a]pyrene and benzo[g,h,i]perylene (200 mg PAH kg(-1) sandy-loam soil) by 5% SMC was obtained in two days under continuous shaking at 80 degrees C. The SMC-treated PAH samples had significantly reduced or removed their toxicities as revealed by the Microtox bioassay. These results were confirmed by gas chromatography-mass spectrometry analysis on the breakdown products. A phthalic derivative which is reported as a degradative product of PAHs by ozonation or ligninolysis was also detected in the SMC-treated samples. The results demonstrate the potential in employing SMC in ex situ bioremediation.
Article
Maximum challenge exposure of Liposcelis bostrychophila to Beauveria bassiana, Paecilomyces fumosoroseus, Aspergillus parasiticus or Metarhizium anisopliae resulted in no more than 16% mortality. We investigated several of L. bostrychophila's cuticular lipids for possible contributions to its tolerance for entomopathogenic fungi. Saturated C14 and C16 fatty acids did not reduce the germination rates of B. bassiana or M. anisopliae conidia. Saturated C6 to C12 fatty acids that have not been identified in L. bostrychophila cuticular extracts significantly reduced germination, but the reduction was mitigated by the presence of stearamide. Cis-6-hexadecenal did not affect germination rates. Mycelial growth of either fungal species did not occur in the presence of caprylic acid, was reduced by the presence of lauric acid, and was not significantly affected by palmitic acid. Liposcelis bostrychophila is the only insect for which fatty acid amides have been identified as cuticular components. Stearamide, its major fatty amide, did not reduce germination of B. bassiana or M. anisopliae conidia or growth of their mycelia. Adhesion of conidia to stearamide preparations did not differ significantly from adhesion to the cuticle of L. bostrychophila. Pretreatment of a beetle known to be fungus-susceptible, larval Oryzaephilus surinamensis, with stearamide significantly decreased adhesion of B. bassiana or M. anisopliae conidia to their cuticles. This evidence indicates that cuticular fatty amides may contribute to L. bostrychophila's tolerance for entomopathogenic fungi by decreasing hydrophobicity and static charge, thereby reducing conidial adhesion.
Conference Paper
Dielectric polarization may be induced in polar and nonpolar electrically insulating polymers by externally applied electric fields. Such polarization may arise from dipolar orientation and injected space charges in polar and nonpolar materials respectively. Present work reports the results of a study of the nature of field induced polarization in cross-linked polyethylene (XLPE) by laser intensity modulation method (LIMM) and dielectric spectroscopy. An analysis of the data obtained by these two techniques, together with FTIR and DSC results, shows that the induced polarization may originate from a simultaneous presence of both the dipolar orientation and injected space charges
Wood-fibre composites: Stress transfer and hygroexpansion
  • K M Almgren
Almgren, K.M., 2010. Wood-fibre composites: Stress transfer and hygroexpansion. http:// www.diva-portal.org/smash/record.jsf?pid=diva2%3A309582&dswid=-9983 (20 Feb 2020).
Importance of lignin modifying enzymes from isolated white rot fungus in lignin degradation
  • M Bisht
  • N Rathi
  • J Rai
Bisht, M., Rathi, N., Rai, J., 2017. Importance of lignin modifying enzymes from isolated white rot fungus in lignin degradation. Int. J. Innovative Res. Sci. Eng. Technol. 6, 2347-6710.
How Does Temp Affect the Growth Rate of Crytals?
  • C Gillespie
Gillespie, C., 2018. How Does Temp Affect the Growth Rate of Crytals? https://sciencing. com/temp-affect-growth-rate-crystals-6318908.html (29 April 2020).
Why is Fire Hot? How Hot is it
  • A M Helmenstine
Helmenstine, A.M., 2020. "Why is Fire Hot? How Hot is it?". https://www.thoughtco. com/why-is-fire-hot-607320 (24 Feb 2020).