Research Articles

Effects of UV-light irradiation and water spray on the mechanical strength and surface characteristics of untreated and pretreated Scots pine sapwood samples were studied. The specimens were treated with parsley seed oil, pomegranate seed oil, linseed seed oil, nigella seed oil, canola oil, sesame seed oil, and soybean oil. The compositional changes and surface properties of the weathered samples were characterized by Fourier transform infrared (FTIR-ATR) spectroscopy and color and surface roughness measurements. The results showed that all vegetable oils provided lower color changes than the control group after 600 h of exposure in a weathering test cycle. The least color change was found on the Scots pine surface pretreated with pomegranate seed oil. The vegetable oil treatment retarded the surface lignin degradation during weathering, indicating that the surface roughness values of pine wood treated with vegetable oils decreased with irradiation over time compared with those of control samples. The effect of artificial weathering on mechanical strength was determined with a compression strength test. It was observed that the compression strength values of Scots pine samples treated with vegetable oils was higher than that of untreated samples after 600 h of weathering exposure.

To improve the interfacial compatibility between bamboo powder and polypropylene (PP), the effects of maleic anhydride-grafted polypropylene (MAPP) on the physico-mechanical properties and rheological behavior of 33 wt% bamboo powder/PP foamed composites were investigated. The results showed that the mechanical properties, water resistance, and surface wettability of MAPP-treated composites improved significantly, and the optimum content of MAPP was 9%. The density of 9% MAPP-treated composite was 0.845 g/cm3 and its specific bending and tensile and notched impact strengths increased by 22.9%, 29.6%, and 49.0%, respectively, and the water absorption decreased from 8.80% to 1.92%, compared to the untreated composite. The frequency sweep results indicated that both the modulus and complex viscosity of the 9% MAPP-treated composite reached minimum values, and the slope of the lgG’-lgf curve for the treated composite increased by 15.9% compared with that of the untreated analogue. ESEM results indicated that the MAPP-treated composite had better bamboo powder dispersion and better interfacial compatibility. FTIR and XPS analyses confirmed the esterification between anhydride groups of MAPP and hydroxyl groups of bamboo powder. XRD studies showed the degree of crystallinity for the MAPP-treated composite increased to 26.52%, compared to 21.05% for the untreated composite.

treated with a nano-ZnO solution at four treatment levels (0, 10,000, 20,000, and 40,000 ppm) using a modified dip method. Also, a thermal treatment was performed at 60 and 120 °C. After conditioning the samples, water absorption, volumetric swelling, water repellency effectiveness, and anti-shrink/anti-swell efficiency were determined within 24 h of soaking time. The results indicated that the nano-ZnO used for wood modification greatly improved dimensional stability and reduced the hygroscopicity of the wood. In addition, the Fourier-transform infrared spectroscopy (FTIR) analysis suggested a strong interaction between the nano-ZnO and the chemical components of wood. The heat treatment effectively improved the effects of nano-ZnO.

Thermal properties of wood and modified wood-based materials are important parameters that influence the manufacturing process and final industrial utilization. The aim of this work was to investigate three main thermal properties (thermal conductivity, thermal diffusivity, and specific heat capacity) of ammonia-treated compressed beech wood (Lignamon material) and natural beech wood (Fagus sylvatica).These properties were measured based on the quasi-stationary method developed at the Department of Wood Science at the Technical University in Zvolen. The influence of increased density (caused by ammonium treatment and compression) of four different types of Lignamon material on the thermal properties was discovered, and the results were compared with those from untreated beech wood. The results confirmed a dependency on the density of the material. With increasing Lignamon compression extent (increasing density value), the thermal conductivity increased and the thermal diffusivity decreased. The maximum value of thermal conductivity reached (0.26 W.m^-1.K^-1 at 1070 kg.m^-3) in the case of Lignamon 6k and (0.26 W.m^-1.K^-1 at 950 kg.m^-3) in the case of Lignamon 7n.

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.