Volume 8 Issue 4

This paper reports on the total deformation and loading force after plasticizing beech wood by microwave heating. There have been few studies devoted to the examination of microwave heating for plasticizing of beech wood. Therefore, a procedure was developed to verify the use of microwave heating for the purpose of plasticizing. Total deformation and loading force were investigated on beech samples immediately after plasticizing by microwave heating. The samples were loaded with pressure applied parallel to the grain. Measured results served the purpose of quantifying total deformation. The investigated factors (wood moisture and plasticizing time) had significant influences on the loading force and total deformation of beech wood plasticized by microwave heating. Increasing initial wood moisture increased total deformation. Increasing plasticizing time decreased the total deformation of wood because of a larger loss of wood moisture. Loading force had contrary behavior: increasing wood moisture decreased the loading force, and increasing plasticizing time increased the loading force.

High-yield pulps (HYP, including BCTMP and APMP) have been increasingly used in various paper grades due to their unique properties. However, higher bulk at a fixed tensile strength is desirable for most HYP applications. This study explored the possibility of changing the bulk-tensile relationship of an aspen PRC-APMP pulp by adding fines from a well-refined HYP into a high freeness HYP (backbone pulp). The effect of backbone pulp freeness on the property-freeness relationship of the fines-reinforced pulps was also examined. The results indicate that to reach a target freeness, adding fines from a well-refined pulp (refined by a PFI mill at 20,000 revolutions) to a high-freeness pulp can help achieve a higher bulk and light scattering while maintaining a similar tensile strength, which is desirable in most of the HYP applications. To reach the same tensile index at a range of 20 to 24 Nm/g, the bulk of APMP550-fines (produced by fines and a pulp at 550 mL freeness) was 12 to 17% higher than that of the control pulp. The higher the freeness of the backbone pulp, the higher was the bulk and light scattering coefficient of fines-reinforced pulp when the fines-reinforced pulps were compared at the same freeness.

The properties of P-RC APMP effluent, including relative density, Baume degree, viscosity, surface tension, specific heat capacity, boiling point rise (BPR), and elemental contents of the effluent, were studied. Results indicated that relative density, viscosity, Baume degree, and solids content all displayed a direct proportional correlation; however, there was an inverse linear relationship between Baume degree and temperature. Viscosity rose sharply when the solids content was more than 40%. Surface tension gradually decreased with the rise of solids content. However, when the solids content was over 35%, it increased with an increase in solids content. Specific heat capacity was closely related to the solids content, but it was reduced with an increase in solids content. BPR was proportional to effluent solids content, especially when the solids content exceeded 30% with an uptrend in BPR.

nanocrystalline cellulose (NCC) was prepared from cotton fiber by a single-step method under mild conditions using anhydrous phosphoric acid as the solvent. The absorbance peak of O-H was reduced, and the absorbance peaks of C=O and CH3 appeared in the Fourier transform infrared (FTIR) spectrum of the acetylated NCC with respect to that of the unmodified NCC. The roughly estimated degree of substitution was a little greater than 1.5 by FTIR analyses, implying that most of the free hydroxyl groups on the NCC surface were acetylated at 40 °C for 3 h. The carbons of the acetyl groups were clearly identified in the 13C cross polarization-magic angle spinning (CP-MAS) nuclear magnetic resonance (NMR) spectrum. The zeta potential was reduced from -32.12 mV to -20.57 mV after acetylation. Transmission electron microscope (TEM) and field-emission scanning electron microscope (FESEM) images showed that they were thread-like nano-crystals with a diameter less than 5 nm. Crystal structure analysis using X-ray diffraction (XRD) demonstrated that the acetylated NCC had the typical CelluloseⅡstructure. The PLA film reinforced with 3 wt% acetylated NCC content exhibited the highest tensile strength, which was increased by 117% compared to the control. SEM observation demonstrated good interfacial interaction between the acetylated NCC and the matrix.

One hundred and thirty samples of resupinate white-rot fungi were collected from natural sites in Northern Thailand during the dry season (October-December) as a bioresource for lignin-degrading enzymes (laccase (Lac), lignin peroxidase (LiP), and manganese peroxidase (MnP)). All 130 isolated fungal strains grew well in potato dextrose broth and produced lignin-degrading enzymes at different levels after 7 days of incubation. The selected resupinate fungi, RCK783S, produced maximum Lac at 4,218 U/L, whereas MnP and LiP activities were detected at relatively low levels in all selected fungal strains. The RCK783S was further identified as a new record of Fibrodontia sp. in Thailand. Response surface methodology (RSM) was applied to evaluate the effect of medium composition, i.e., peptone, glycerol, L-asparagine, and CuSO4, on Lac production by Fibrodontia sp. RCK783S. The experiments showed optimum concentrations of peptone, glycerol, L-asparagine, and CuSO4 at 0.625, 15.00, 2.188, and 0.003 g/L, respectively, to produce the highest Lac concentration of 6,086.01 U/L, a 1.44-fold increase from that in the original medium. In addition, the degradation of Eucalyptus camaldulensis was investigated during the solid-state cultivation of Fibrodontia sp. RCK783S. The results showed that lignin was degraded, with lignin loss being 18% after 30 days, coinciding with the highest released Lac activity.

Two particulate amphoteric larch tannin (CLT) products (CTD and CTB) were prepared by cross-linking reactions, and their acid dyes removal abilities were investigated. The effects of several parameters such as pH, contact time, and particle doses were tested, and the acid dyes removal behaviors of both types of particles were compared. The removal of azo acid dyes on CTD and CTB was pH-dependent, and the maximum removal of ≥90.7% was reached for Acid Black 10 B and 52.6% for Acid Red 14 in aqueous solution at pH 5.0. The effect of particle dosages on the removal of Acid Black 10 B and Acid Red 14 was important for two modified CLT particles. An excessive amount of modified CLT particles increased the chromaticity of water samples and caused the decline of dyes removal. Zeta (ζ) potential data revealed that the main mechanism of removal of the acid dyes on the CTD and CTB particles was charge neutralization.

Chemical modification of natural fibres has been carried out using different methods for such purposes as reinforcement in polymer matrices and heavy metals adsorption. In this work, palm fibres were modified by zirconium oxychloride in situ. The palm fibres that had been chemically modified were compared to those in nature using fibres that passed through 20 and 40 mesh screens to evaluate the influence of particle size on modification. Palm fibres were modified with ZrO2.nH2O nanoparticles through the use of zirconium oxychloride in an acidic medium in the presence of palm fibres using ammonium solution (1:3) as the precipitating agent. Scanning electron microscopy (SEM), X-ray diffraction (XRD), infrared spectrophotometry (FTIR), and atomic emission spectrometry with inductively coupled plasma (ICP-AES) were used to characterize the hybrid materials. Results indicated that the particle size of the palm fibres influenced in the modification, because the fibres with smaller particle size had a greater deposition of inorganic material. The ICP technique revealed an increase of 21% nanoparticles ZrO2.nH2O deposited on fibres (40 mesh) when compared to fibres (20 mesh). The diameter of nanoparticles ZrO2.nH2O deposited on fibres was about 50 to 220 nm, as observed by SEM.

This work investigated the ability of biopretreatment with different white-rot fungi to improve the medium-temperature pyrolysis of biomass. It was found that biopretreatment can significantly increase the production of phenols and glucopyranoside up to 2.82 and 2.94 fold, respectively. Biopretreatment can also decrease the content of carbon dioxide, propanol, and propanone, making the pyrolysis more efficient and product-oriented. Moreover, distinct bio-deconstruction mechanisms can result in different pyrolysis products. By deconstructing cellulose and modifying lignin with a minimum of demethoxyation, white-rot fungus Irpex lacteus CD2 can improve the production of acetaldehyde (up to 6.72%) and methoxyl substitutes such as dimethoxyphenyl (up to 21.59 folds). By decomposing carbohydrates, carbonxyl, and methoxyl groups, white-rot fungi Pleurotus ostreatus BP2 and Echinodontium taxodii 2538 can increase the production of D-allose (up to 3.09%) and formic acid (up to 6.98%), while decreasing the methoxyl substitutes such as 2-methoxy-4-vinylphenol (up to 70.08%).

Talc was incorporated as filler alongside rattan powder in polypropylene (PP) matrix to produce a hybrid composite. 20 phr of rattan powder was used for all samples. Talc filler loadings were varied from 0 to 10 phr. The composite was manufactured using a Polydrive Thermo Haake internal mixer, which provided processing characteristics for the composite. Peak and stabilization torques gradually increased with increasing talc filler loading. Tensile properties of the hybrid composites showed an increase in tensile modulus and a decline in elongation at break with increasing talc loading. The tensile strength was enhanced with the addition of talc up to a loading of 4 phr and then decreased with further talc filler loading. A water absorption test was carried out, whereby the water uptake of the hybrid composites was reduced with higher talc filler loading. Thermal degradation of the composites was analyzed by studying thermogravimetric analysis (TGA) thermograms and derivative thermogravimetry (DTG) curves, which showed improvement in the thermal stability of the composite with higher talc content. The morphological studies carried out on tensile-fractured surfaces of the hybrid composites explained the enhancement and deterioration of tensile properties with regard to different filler loadings.

The formation of oxalate during oxygen delignification causes a number of operational problems in pulp and paper mills. In this work, the oxygen delignification of wheat straw pulp was carried out under various conditions and the concentration of resulting oxalate in the effluent was determined. The experimental results show that the amount of oxalate in the effluent was closely related to the reaction conditions, specifically reaction temperature, oxygen pressure, and alkali charge. Raising reaction temperature and/or oxygen pressure could promoted oxalate formation. The oxalate concentration increased linearly with the consumption of alkali but logarithmically with reduction of kappa number. An empirical model for describing the oxalate formation in the oxygen delignification of wheat straw pulp was generated with a reasonably high correlation coefficient (R2=0.909), which can provide useful guidance for control of oxalate formation during oxygen delignification through adjustment of process parameters.