Research Articles

Wood-TiO2 (titania) composites were prepared by a sol-gel process, in which wood was impregnated with the precursor solutions prepared from tetrabutyl titanate (TBT), followed by a curing step. The surface morphology and moisture absorption behavior of the wood composites, as well as their thermal and mechanical performances, were examined. Environmental scanning electron microscopy (ESEM) analysis revealed that TiO2 gels were deposited principally in the cell lumens and partly in the cell walls, as confirmed by the energy dispersive X-ray (EDX) analysis. By this inorganic modification, the hygroscopicity of wood was significantly reduced and its dimensional stability was improved consequently. Greater amounts of TiO2 gel deposited in the cell lumens were not helpful in enhancing the hygroscopicity of wood. Thermal analysis (TG-DTA) showed that the incorporation of TiO2 gel retarded the thermal decomposition of wood matrix and improved the thermal stability of wood. The incorporated inorganic gel seemed to stiffen the wood cell walls, as indicated by the increased resistance of the wood composites to deformation and collapse in compression.

Release paper is a special paper grade with one or both sides coated with non-sticking materials. Silicone is currently the only material used to produce release paper at the industrial level. Its remarkable properties and availability ensure product quality and sustainability of the industrial production. Meanwhile, the stability of silicone polymers raises serious environmental problems in terms of paper substrate recyclability. Studies are currently under way to evaluate the ability of phosphate esters as a new class of compounds capable of developing non-adhesive surface properties. This paper presents initial attempts to coat the paper with phosphate esters and to assess phosphate ester / fibrous substrate and phosphate ester / adhesive interactions. The results show that this class of compounds exhibits non-adhesive properties and, when coated on paper under certain conditions, can lead to a non-sticking surface. Despite the fact that there is a long way to achieve ester anchoring to surface fibers and to control the peeling force from an adhesive tape, preliminary results are encouraging.

The tensile strength behavior and recyclability of the paper prepared with the addition of polyamideamine-epichlorohydrin (PAE) were investigated. The dry and wet tensile strengths obtained with different PAE dosage were measured. The highest wet-to-dry strength ratio of 35% was obtained at 10 mg/g; above this addition level wet strength dropped slightly and then remained constant. The repulpability of strengthened paper was correlated directly with wet strength. The effect of electrolyte on tensile strength was also quantified by varying sodium chloride and calcium chloride concentration in the furnish stock. Without PAE, high salt concentrations (100 mM) reduced the tensile strength by 15-20%. At constant PAE addition level of 10 mg/g, low levels of salt addition (of either 10 mM NaCl or 10 mM CaCl2) slightly improved the strength; paper strength decreased at high salts concentrations. The cation valency and concentration in the process water were important variables which affected the efficiency of PAE. These results present the significance of developing sustainable wet strength agents that can be applied in demanding salty conditions while maintaining the product recyclability.

In an effort to achieve high mechanical performance and improved dimensional stability, densification combined with . was determined. OHT at 180, 200, and 220ºC for 1, 2, and 3 hours was applied to densified Aspen (Populus tremuloides) veneers. OHT was found to be an efficient treatment to reduce the hygroscopicity of densified aspen veneers, although OHT had a negative impact on Brinell hardness. However, due to the contribution of densification, the hardness of oil-heat treated veneers was still two to three times higher than that of non-densified veneers. Similar results were found for tensile strength. Bending strength increased slightly at low OHT temperature, and then decreased at high temperature. Bending strength of oil-heat treated densified veneer samples was higher than that of non-densified ones. No significant effect of OHT was found on tensile MOE, but bending MOE increased after OHT. Compared to OHT duration, OHT temperature had a larger impact on densified wood hygroscopicity and mechanical properties.

The main objective of this research was to study the potential of waste polypropylene and waste newsprint fiber for making wood-plastic nanocomposites. We used 30 wt.% waste newsprint fiber and 10 wt.% compatilizer in this study. Nanoclay was used at two levels: 2.5 and 5% by wt. Materials were mixed with either recycled or virgin polypropylene. The effects of nanoclay (NC) on the mechanical and thermal properties were also studied. The improvements in tensile properties of the blended composites with the addition of NC were further supported by Scanning Electron Microscope (SEM) micrographs and X-Ray Diffraction (XRD) data. Thermal degradation behavior of the composites showed that the degradation temperatures shifted to higher values after addition of nanoclay. The XRD data showed that the relative intercalation of composites with 2.5% nanoclay was higher than 5% nanoclay. The experimental results demonstrated that the waste materials could be used as appropriate alternative raw materials for making low cost wood-plastic composites (WPCs).

sodium dodecyl sulfate (SDS) and a modified polyacrylic acid solution (MPA) on a soybean meal adhesive were investigated. Three-ply plywood specimens were fabricated to measure the water resistance of the adhesive (three-cycle soak test). The viscosity and solid content of the adhesive were measured. The cross-section and functional groups of the cured adhesive were evaluated using scanning electron microscope (SEM) and Fourier transform infrared (FTIR) spectroscopy, respectively. The results showed that using SDS improved the water resistance of the soybean meal adhesive by 30%. After incorporating MPA, the water resistance of the soybean meal/SDS/MPA adhesive was further improved by 60%, the viscosity of the adhesive was reduced by 81%, and the solid content of the adhesive increased by 15%. The plywood bonded by the soybean meal/SDS/MPA adhesive met the interior plywood requirements. SEM results showed no holes and cracks on the cross-section of the cured soybean meal/SDS/ MPA adhesive. FTIR analysis indicated that more peptide linkages were formed in the cured adhesive as MPA was incorporated.

Natural rubber (NR) composites were prepared by the incorporation of rattan (Calamus Manan) powder at filler loadings in the range of 0 to 30 phr into a natural rubber matrix with a laboratory size two roll mill. The particle size of rattan powder was less than 180 µm. The biodegradation of the rattan powder-filled natural rubber (NR) composites were investigated as a function of filler loading and a silane coupling agent. A soil burial test was carried out for six months, and the degradation of the NR compound and the NR composites was evaluated through tensile testing. Morphological properties were determined using scanning electron microscopy (SEM) to evaluate the degradation of the samples after six months of soil exposure. The results indicate that the tensile strength, elongation at break, and stress at 100% elongation (M 100) all decreased after soil burial testing due to the biological attack by microbes onto the sample. Improvement in tensile properties was seen with the addition of the silane coupling agent due to better adhesion between the rattan filler and the rubber matrix. The deterioration in tensile properties due to the biodegradation process was confirmed by SEM and FTIR studies.

Catalytic conversion of formic acid into methanol was investigated with Cu as a catalyst and Al as a reductant under hydrothermal conditions. It was found that formic acid can be converted into methanol by such means. The highest yield of methanol (30.4%) was attained with a temperature of 300 °C and a reaction time of 9 h. The AlO(OH) formed from Al oxidation may also play a catalytic role in the formation of methanol. This process may provide a promising solution to producing methanol from carbohydrate biomass combined with the process of converting the carbohydrate into formic acid, which is expected to emit no CO2.

White rot fungi can be used as a pretreatment of biomass to degrade lignin. It also alters the structure of the lignocellulosic matter, thus increasing its accessibility to enzymes able to convert polysaccharides into simple sugars. This study compares the ability of two species of white rot fungi, Pycnoporous sanguineus and Oxyporus latemarginatus FRIM 31, to degrade lignin in kenaf chips. The white rot fungi were originally isolated from the tropical forest in Malaysia. Kenaf chips were first inoculated with each fungus separately using corn steep liquor as a fungal growth promoter. The kenaf chips were inoculated with white rot fungus for a period of 1, 2, 4, 8 and 16 weeks, after which they were observed under the scanning electron microscope (SEM). Chemical analyses were conducted following TAPPI Standard Methods and Fourier Transmission Infra Red (FTIR). SEM observations showed evidence of fungal colonization. When calculating weight loss, both P. sanguineus and O. latemarginatus FRIM 31 showed the greatest reduction. Amounts by mass of cellulose, hemicelluloses, extractives, and lignin in the treated kenaf chips all were lowered. The results show that O. latemarginatus FRIM 31 had a greater ability to degrade lignin when compared to P. sanguineus .

Mg-Al-CO3 LDH was synthetized, using co-, and was used in flame-retardant paper as filler. The crystallizations, granularities of Mg-Al LDH, and characters of flame-retardant papers were investigated through XRD, FT-IR, TEM, TG-DTA, and SEM techniques. The results indicated that Mg-Al hydrotalcites were layered hexagonal nanoparticles, with high positive charge density, perfectly crystallized structure, and striking performance in furnish retention improvement. Mg-Al hydrotalcites with high whiteness can improve the whiteness of flame-retardant paper; the whiteness of flame-retardant paper increased by 82.1% while the dosage of LDH was 20wt%, but the Mg-Al hydrotalcites affected the strength index of flame-retardant paper adversely. The flame-retardant papers based on fiber using Mg-Al hydrotalcites as fillers showed excellent inflaming retarding performance. The oxygen index of the flame-retardant paper produced was above 25% at the dosage of 20wt%.