Volume 3 Issue 4

Unmodified and modified rice husk powder filled PVC composites were prepared having different amounts of rice husk powder. Mechanical, thermal, and electrical properties of these composites were determined. The tensile strength of rice husk powder PVC composites having 0, 10, 20, 30, and 40 weight percent of rice husk powder was found to be 33.9, 19.4, 18.1, 14.6, and 9.5 MPa, respectively. Adding of maleic anhydride- modified rice husk powder improved the tensile strength of rice husk powder PVC composites. Flexural strength and flexural modulus of composites increased on treatment of rice husk powder due to the improved bonding between rice husk powder and PVC matrix. Arc-resistance of rice husk powder PVC composites was not affected on increasing loading of the powder. Volume resistivity and surface resistivity decreased with increasing loading due to the presence of impurities and water molecules. Vicat softening temperature increased with rice husk powder loading. Addition of rice husk increased the melting temperature of the composite matrix as compared to pure PVC.

Manure, an animal waste product with many negative economic and environmental issues, can today be converted using anaerobic digestion technology into a number of commercial products ranging from fertilizer, compost, animal bedding, and plant bedding. A number of new uses are now being explored such as bioenergy (both electrical and biofuel) and a lignocellulose-rich potential feedstock for engineered biocomposite products for building materials. This paper explores the engineering potential of using anaerobically digested bovine biomass (ADBF) as a feedstock material for biocomposite building materials. Our evaluation generally indicated that making dry-formed fiberboard using up to a 50/50% mixture of wood fiber and ADBF-fiber compared favorably with some commercial requirements for wood-based medium-density fiberboard and particleboard.

This paper explores the physical and economic potential to substitute anaerobically digested bovine biofiber (ADBF) for wood in the making of particleboard. Laboratory tests indicated that replacement of one-half the wood in particleboard with ADBF produced panels that compared favorably to the requirements for commercial particleboard performance (specified by ANSI Standard A208.1–1999). The economic question hinges on the opportunity costs of alternative uses for ADBF. The current use is primarily animal bedding, and prices appear to be greater than those paid by particleboard plants for sawdust and planer shavings but less than for chips. ADBF is most similar in size to, thus most likely to be substitutable for, sawdust and shavings. At current bedding values, use for particleboard appears a less favorable alternative. However, this could be overcome by large-volume, long-term contractual arrangements that provide a secure long-term outlet for excess ADBF fiber that may otherwise not have value. For a particleboard operation, the opportunity for fiber diversification and the incorporation of post-industrial waste in the process offer strategic advantages.

Chemical and thermal stability of rice husks against alkali treatment with 2 to 8% w/v NaOH are presented and discussed in this paper. The thermal stability of the rice husks was examined by using a thermal gravimetric analysis instrument. Chemical stability was evaluated by examining the organic components of rice husks using proximate analysis. The results indicated that the proportion of lignin and hemicellulose in rice husks treated with NaOH ranging from 4 to 8% decreased significantly by 96% and 74%, respectively. The thermal stability and final degradation temperatures of the alkali-treated rice husks were also lowered by 24-26°C due to degradation of hemicellulose and lignin during alkali treatment. Absence of the onset degradation zones in the alkali-treated rice husks was a further indication that hemicellulose and other volatile substances degraded during alkali treatment. This leads to a conclusion that alkali treatment of rice husks with more than 4% NaOH causes a substantial chemical degradation of rice husks, which subsequently decreases their thermal stability.

A series of comparable specimens of hornbeam wood were submitted to pretreatments by white-rot fungi, by alkali alone, or by alkali and oxidizing agents. The pretreatments caused weight loss of wood and modified its physical properties and chemical composition. All pretreat-ments reduced markedly axial permeability of the test specimens in the wet state (w > FSP). The chemical pretreatments of the test specimens, however, increased the rate of diffusion in the direction parallel to the grain. All pretreatments made the kinetics of wood/water interactions in the initial phase much higher, especially when white-rot fungi were used. The chemical pretreatments caused extreme swelling of wood, and on the other hand, drying of the pretreated specimens to their initial moisture content resulted in extremely deep reduction of their dimen-sions. An increased rate of wood/water interactions, high uptake of water, and higher diffusion coefficients of wood pretreated by alkali may positively influence the pulping processes.

A series of comparable specimens of hornbeam wood were submitted to fungal and chemical pretreatments. Two strains of erosive white-rot fungi (P. chrysosporium and T. versicolor) and a lignin-selective fungus C. subvermispora were used. Chemical pretreatments were carried out with diluted sodium hydroxide, or sodium hydroxide and then by hydrogen peroxide, or per-acetic acid. Both biotic and abiotic pre-treatments modified the chemical composition of wood and were accompanied by its weight loss. The applied fungi apparently delignified the specimens, however at the expense of cellulose, especially when the erosive strains of fungi were used. The chemical pretreatments caused deep deacetyl-ation, and milder delignification of wood and did not cause an apparent loss of cellulose. Biotic pretreatments of hornbeam wood, despite their marked delignification effect, led to unexpected increase in the contents of residual lignin in the resulting kraft pulps. On the other hand, pulping of the chemically pre-treated chips yielded pulps with low contents of residual lignin and much higher brightness.

Three commercial silicone emulsions with different functional groups i.e., quat-silicone micro-emulsion (<40 nm particle size), amino-silicone macro-emulsion (110 nm), and silicone macro-emulsion with alkyl-modified side groups (740 nm) were used to protect wood samples against fungal decay. The addition of the emulsions to an agar growth medium revealed that all three silicone formulations inhibited the growth of Coniophora puteana and Trametes versicolor compared to the controls without silicone. Wood mini-blocks of pine sapwood and beech wood were treated with 2%, 5%, 10%, and 15% concentration of silicone emulsions and tested for their resistance against basidiomycete decay. Quat-silicone and amino-silicone emulsions at higher concentrations imparted resistance of wood to both types of basidiomycetes, while the alkyl-modified silicone formulation did not enhance the resistance. In a soft rot test according to ENV 807, wood treated with an amino-sililcone emulsion showed the lowest weight loss and loss of dynamic MOE. Quat-silicone micro-emulsion had a lower effect, while the alkyl-modified silicone emulsion did not cause reduction in weight and strength loss compared to the untreated controls. The increased resistance against soft rot might be attributed to a lag in fungal colonization rather than to a sustained effect of protection.

Polymer adsorption on cellulose nanofibrils and the effect on nanofibril water binding capacity were studied using cellulose nanofibril films together with quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance (SPR). The experiments were performed in the immersed state, and special attention was paid to the effect of polymer properties on the water content and viscoelastic properties of the polymer/fibril layer. The dry mass of the adsorbed polymers was determined using SPR. The type of the adsorbed polymer strongly affected the water content and viscoelastic properties of the nanofibril film. The adsorption of a highly charged flocculating polymer, PDADMAC, caused dehydration of the film, which was also detected as nanofibril film stiffening. The adsorption of xyloglucan introduced a dispersing effect to the nanofibril film, which was detected as a loosening and softening of the nanofibril/polymer layer. A dispersing effect was also achieved with carboxymethyl cellulose (CMC), but CMC did not adsorb irreversibly on the nanofibril surfaces. In addition to the nanofibril film studies, the effect of polymer adsorption on cellulose nanofibril suspension aggregation was demonstrated using confocal laser scanning microscopy (CLSM). Xyloglucan was shown to open the nanofibril aggregate structures and act as a dispersing agent, whereas the other polymers studied did not have as significant an effect on aggregation.

Switchgrass varieties grown under various environments were investigated by dispersive and Fourier Transform Near-Infrared (NIR) spectrometers. The collected NIR spectra were analyzed using multivariate approaches. More specifically, principal component analysis (PCA) and projection to latent structures (PLS) regression techniques were employed to classify and predict characteristics of the switchgrass samples. The multivariate results were compared to reflectance indices that are commonly used to study the physiological performance of plants. From near infrared spectra, discrimination between the two growth locations was successfully achieved by PCA. Separation based on the ecotype and the rate of fertilizer applied to the field was also possible by the multivariable analysis of the spectral data. For the classification/ discrimination of the switchgrass samples, the near infrared spectra collected by the dispersive and the Fourier Transform spectrometers provided similar results. From the two near infrared data sets robust models were developed to predict non-structural carbohydrates content and the rate of nitrogen applied to the field. However, the spectra collected by the dispersive spectrometer resulted in more accurate models for these samples.

In an effort to devise inexpensive and sustainable production of ethanol fuel, experiments were conducted to establish conditions for Pichia stipitis NRRL Y-7124 to ferment a membrane treated wood hydrolysate derived from sugar maple to produce ethanol. The degree of aeration required to effectively utilize xylose, produce ethanol, and minimize xylitol formation as well as the optimal hydrolysate concentration were the conditions examined. P. stipitis produced the highest concentrations of ethanol in shake flasks at 150 rpm (14.3 g/L in 71 h), and 50% hydrolysate maximized ethanol yield (12.4 g/L in 51.5 h). In the 50% hydrolysate cultures, P. stipitis produced ethanol at a rate of 0.24 g/L×h with a yield of 0.41 g ethanol/g wood-derived carbohydrate.