Volume 10 Issue 1

It is preferred to perform conformity assessment of wood-based panels on the whole panel without cutting it down to smaller pieces. The modulus of elasticity, a mechanical property of wood, was determined by longitudinal vibration testing with the full-size panel, and the results were compared with results of tests of prismatic beams. The Brancheriau’s correction coefficient was used to compensate for errors from cross-sectional dimension variations and errors from Poisson’s ratio. Longitudinal excitation of the panels along the length was shown to be successful in evaluating the modulus of elasticity. However, strong correlations obtained from plate and beam comparisons along the width of the panels are promising.

The use of rape straw in ruminant production is limited by its high lignin content and low ruminal degradability. White rot fungi are the most efficient known degraders of lignin. Four white rot fungi were investigated for their potential to degrade lignin and improve rumen fermentation of rape straw. Solid state fermentation of the straw was carried out for 0 to 30 days to determine changes in chemical composition and in vitro rumen fermentation. Results showed that Phanerochaete chrysosporium and Lentinula edodes degraded about 45% of lignin and enhanced the in vitro organic matter digestibility (IVOMD) and volatile fatty acid production; however, about 55% of the cellulose was lost after 30 days of incubation. Ceriporiopsis subvermispora and Phlebia acerina degraded a fraction (< 30%) of lignin and cellulose, but inhibited ruminal fermentation. Fungal incubation increased the chitin content of rape straw. Regression analysis showed that the IVOMD increase depended on the combined action of neutral detergent fiber loss and chitin content increase in rape straw. This study indicates that considerations of the conversion of rape straw into ruminant feed with white-rot fungi should take into account the degradation of lignin, fiber loss, and the chitin produced along with the growth of fungi.

The bonding interface of loblolly pine veneers cured with epoxy/wood pyrolysis bio-oil resins was studied. The shear strength of the adhered strands was calculated to examine the effect of bio-oil addition on epoxy resin performance. The chemical structure, curing behavior, and microstructure were investigated to analyze the interaction between wood substrate and resins. Results showed that the strength of pine wood-resin joints gradually decreased as more bio-oil was added. However, this effect was not apparent when the substitution rate was lower than 30%. ATR-FTIR analysis confirmed that complex chemical reactions take place between wood constituents and epoxy/bio-oil resins involved in the cross-linking at the interface. The reaction degree of -OH and C-O-C functional groups plays a key role in regulating the bonding stress of the wood bond line. The addition of bio-oil accelerated the polycondensation cross-linking process, resulting in a decreased cure temperature. SEM and optical microscopy showed that the epoxy/bio-oil resin formed gel nails in the pit and tracheid gaps, leading to the closing of the capillaries of the wood’s cell walls and the colloidal interface extending into the timber micro-capillary system.

Camellia nut shell (CNS) is known as an important bio-resource that has great potential as a biomaterial. The elemental composition, chemical structure, crystallinity, and pyrolysis characteristics were analyzed in this paper for six species of CNS. The concentration of organic carbon, N, K, and Na in CNS ranges from 44.40 to 48.60%, 2.91 to 4.42 mg.g-1, 7.67 to 13.80 mg.g-1, and 0.02 to 0.26 mg.g-1, respectively. The content of lignin, cellulose, hemicellulose, and ash varies between 30.07 and 36.23%, 13.87 and 20.95%, 35.15 and 49.34%, as well as 2.00 and 4.75%, respectively. Camellia nut shell cellulose crystalline structure belongs to typical cellulose type I, and the cellulose crystallinity index for the six species ranges from 37.4 to 62.3%. The CNS pyrolysis process can be divided into three phases, and the substantial degradation occurs within the temperature range of 200 to 430 °C, with nearly 60% loss of weight. The temperature could be reduced greatly during pyrolysis under acidic conditions with PEG 400/glycerol as a solvent. The degradation rate was impacted by K concentration. Increasing cellulose crystallinity negatively affected the degradation rate.

Global energy sources such as coal and oil are limited, and the burning of such fossil resources creates pollution problems. Wind energy offers one of several promising clean alternatives to carbon-based fuels. However, the composite materials currently available for producing wind turbine blades cannot accommodate the scale-up of wind energy due to their high price and disposal challenges (e.g., carbon fiber/epoxy laminated, fiber-reinforced plastics) or environmental costs (e.g., wood/epoxy laminate materials derived from large-diameter natural forest wood). The purpose of this study was to explore the advantages of the composite bamboo/epoxy laminated material as a more cost-effective, sustainable alternative. Applying the classical theory of composite laminated plates, this study tested a prediction model of the composite bamboo/epoxy laminated material’s elastic modulus values. The model accurately predicted the end product’s elastic modulus values according to the single bamboo board’s elastic modulus values and its manner of assembly, without destroying the material’s basic structure and integrity. The composite bamboo/epoxy laminated material was judged to be less expensive than carbon fiber/epoxy laminated, fiber-reinforced plastics and to have advantageous mechanical properties relative to conventional wood/epoxy laminate materials.

Adhesive-free fiberboards can be self-bonded through high temperature thermo-compression processes. To achieve it, treatments such as steam explosion/injection, as well as chemical and enzymatic oxidation have been implemented. However, the role of extractive components in the structure and cohesiveness of fiberboards has not been fully understood. In this work fibers of leaf plantain were treated with organic solvents and with hot water to remove the extractives, and were then employed to produce self-bonded fiberboards. Treated fibers were characterized by thermogravimetric analysis, electronic paramagnetic resonance, and antioxidant capacity. The mechanical strength of the fiberboards evaluated by three point flexural tests, decreased when fibers were extracted with aqueous solvents, and increased after treatment with organic ones. This can be explained by the effect of water extractives in reducing the initial degradation temperature, and in retaining free stable radicals generated during thermo-compression. In the case of the organic extractive fraction, this inactivates the fibers, which impairs close contact between polar groups and thus decreases the mechanical properties of the fiberboards. According to the results, it is possible to increase the mechanical properties of self-bonded fiberboards by changing the concentration of polar and low molecular weight phenolic compounds.

Valorization of lotus leaf stalks (LLS) produced as an abundantly available agro-waste was achieved through the extraction of value-added nanocellulose. Nanofibrillated cellulose (NFC) was successfully prepared from LLS by using chemical pretreatment combined with high-intensity ultrasonication. The morphological characteristics of the chemically purified LLS cellulose microfibrils were characterized by optical microscopy and MorFi fiber analysis. Fourier transform infrared (FTIR) spectroscopy indicated the extensive removal of non-cellulosic components after chemical pretreatment. The transmission electron microscopy (TEM) results revealed agglomeration of the developed individual NFC, with a width of 20 ± 5 nm and length on a micron scale, into a network-like feature. X-ray diffraction results showed that the resulting NFC had a cellulose I crystal structure with a high crystallinity (70%). The NFC started to degrade at around 217 °C, and the peak rate of degradation occurred at 344 °C. Nanofibrils obtained from LLS have great potential as reinforcement agents in nanocomposites.

Because of the light weight and environmental advantages of natural fibers, an increasing amount of natural fibers have been used to replace synthetic fibers in reinforced unsaturated polyester (UPE). Because of the impact property advantage of coir fibers, coir toughened UPE composites can achieve excellent impacting toughness, but at the cost of a lower tensile performance. In order to get the better comprehensive performance, the tensile strength must be maintained in a higher level, so coir ropes as an appropriate reinforced form were added to UPE matrix. The different weight-percent contents for the coir rope addition were set to achieve coir rope reinforced UPE composites with different coir contents. The tensile test results showed increasing tensile strength with the increased content of coir ropes. To reasonably and accurately predict the composite performance, taking the original performance prediction model based on a continuous reinforced fiber composite (using the Classical Mixed Law as a reference) and assuming each coir rope was ideally continuous fiber, the destructive principle of coir rope reinforced UPE composite under the action of tensile load was analyzed and the tensile failure mechanics model was improved. According to the experimental proof, the new model can be proven to have higher precision accuracy, which can provide new train of thought for the building of the theoretical models for natural fiber reinforced composites, thus guiding the actual production application.

Pretreatment of biomass is an extremely important step in a commercial biorefinery. For realization of lignocellulosic biomass as an alternative fuel source to occur, a fundamental understanding and critical investigation of the chosen pretreatment are essential. In this work, green liquor (GL) pretreatment of four plant species, namely Masson pine, poplar, moso bamboo, and miscanthus, was investigated to understand its effect on the chemical composition and enzymatic hydrolysis of different lignocellulosic materials. The results indicated that herbaceous materials exhibited better delignification selectivity in GL pretreatment than woody materials according to the order: miscanthus > moso bamboo > poplar > Masson pine. The effect of GL pretreatment on the enzymatic sugar yield was rather different depending on the varieties of lignocellulosic materials. Higher lignin removal with less polysaccharide degradation during GL pretreatment improved the enzymatic sugar yield.

Mature 40-year-old trees of Eucalyptus globulus harvested in Portugal were studied to determine the heartwood development and variation of basic density and extractives content at different stem height levels. The heartwood radius decreased regularly from bottom to top in all the trees: for instance 22.2 cm, 13.0 cm, and 10.4 cm, respectively, at the 0%, 35%, and 60% height levels of tree 1. The average sapwood thickness was 2.8 cm at the stem base. The mean basic density fell in a range between 0.607 g cm-3 and 0.782 g cm-3 and was highest in the outer heartwood at all height levels. The total content of extractives varied axially and radially along the stem. It decreased until the 35% height level, and then it remained approximately constant upwards. The extractives content increased radially from the sapwood to the inner heartwood (6.2% to 12.5% at the base). Ethanol-soluble compounds were the major fraction at the base: 4.9%, 8.4%, and 10.9% of dry mass, respectively, for sapwood, outer heartwood, and inner heartwood. The non-polar extractives were obtained by dichloromethane extraction in very low amounts.