Volume 13 Issue 2

The use of biocarbon derived from renewable resources to substitute for petroleum-based carbonaceous materials in composites and other applications often requires size reduction. Biocarbon obtained by the pyrolysis of miscanthus was subjected to ball milling from 2 to 24 h. Particle analysis was performed by combining scanning electron microscope imaging and image-based particle counting. The milled biocarbon had a highly heterogeneous shape and size distribution, making image-based analysis the most suitable method. The average particle size was reduced from above 3 µm after 2 h of milling to below 1 µm after 24 h of milling. The specific surface area doubled from 148 m²/g to approximately 300 m²/g after 2 h of milling, but it did not change with longer milling. Ball milling caused a gradual decrease of the thermal conductivity from 0.137 to 0.116 W·m-1·K-1. The ash content increased from 8 to 17% after 24 h of milling. Polypropylene composites filled with the biocarbon with and without ball milling showed lower density and comparable mechanical properties to a talc-filled composite except for lower impact strength. Using ball milled biocarbon led to a steady increase of the impact strength with longer milling time, reaching values on a par with that of the talc composite.

D-xylose, a hemicellulose model compound, was oxidized by chlorine dioxide under simulated bleaching conditions, and the mechanism of this reaction was investigated. The final reaction product, chloroacetic acid, was detected by gas chromatography-mass spectrometer (GC-MS). To study the generating mechanism of chloroacetic acid by D-xylose during chlorine dioxide bleaching, three reaction pathways were designed. The results showed that the biggest heat of reaction, -234.33 kJ/mol, and the minimum reaction activation energy, 44.44 kJ/mol, appeared for one of the candidate pathways (no. 2). That pathway was thermodynamically more favored. Xylitol was generated by D-xylose degradation, and then chloroacetic acid was generated by a series of oxidation, fracture, and substitution reactions on xylitol.

Heartwood and sapwood samples of Scots pine were subjected to densification and thermal compression (180 °C to 220 °C) using a hot press, and their recovery behaviors and the involved mechanisms were investigated. Compressed wood (CW) showed poor recovery after water uptake. This deformation effectively was fixed by the subsequent high temperature treatment. To explain the phenomenon, the sorption properties of wood before and after modification by the adsorption isotherms were evaluated. The model of Hailwood and Horrobin gave the changes of the monolayer and multilayer sorption of each group samples and the relationship with wood deformation. By analyzing hygroscopic hysteresis, it was found that the removed elastic components from wood under elevated temperature had an inescapable impact on hysteresis ratio and recovery, even if it was not the only cause. In other words, the modified wood’s plasticity was responsible for its recovery.

Wood–plastic composites (WPCs) are experiencing rapid growth in terms of applications where they may be subject to degradation and wear. This paper investigated the effect of sorghum straw (SS) fiber, pretreated with a mixture of stearic and palmitic acids, on the wear behaviors of polyvinyl chloride (PVC) composites in alternated simulated sea water and acid rain aqueous conditions. The results showed that the water resistance of the SS/PVC composites improved noticeably after pretreatment with 0.80 wt% stearic and 0.50 wt% palmitic acid (0.8SA-0.5PA). The SS/PVC composites pretreated with 0.8SA-0.5PA exhibited high water (moisture) resistance, hardness, mechanical, thermal, and wear resistance properties. Exposure to degradative water worsened interfacial bonding, and degraded the matrix strength and heat resistance, which reduced the wear resistance of the SS/PVC composites. The wear mechanism of the SS/PVC composites after 12 d of soaking was abrasive wear.

Bio-ethanol is considered as an important renewable fuel to partly replace fossil-derived fuels. In this study, bioethanol production, which includes cellulase production, saccharification of the cellulose content of sesame seed residue, and ethanol production, was investigated. Out of the hundreds of cellulase-producing bacterial strains isolated from sesame seed residue during this study, the B isolate was found to have the highest cellulase enzyme production. This isolate was identified as Bacillus cereus by 16S rRNA sequencing. The effects of different growth parameters, including inoculum concentration, incubation time, temperature, pH, and carbon and nitrogen sources, were investigated to optimize the growth conditions of the bacterium. The maximum cellulase activity was achieved with an inoculum concentration of 3% after 48 h in a basal medium at a pH of 7 and an incubation temperature of 35 °C. The best nitrogen and carbon sources were yeast extract and sesame seed residue, respectively. The results showed the liberation of 2.3 g/L of reducing sugar by the dinitrosalicylic acid method. This total reducing sugar produced 15 g/L of ethanol after 48 h when Saccharomyces cerevisiae was used as a fermentation agent. Hence, bioethanol was successfully produced from the cellulose of sesame seed residue using the cellulase enzyme from B. cereus.

A proposed method for assessing wood recovery involves application of a machining station approach with volume and mass measurements. A medium wood furniture company located in Jepara, Indonesia was selected to develop the method. Batch measurements of the inputs and outputs for different types of indoor-furniture products at every station were collected and analysed. For the volume method, three dimensions were measured on each specimen: the length, width, and thickness. For the mass method, the specimens were weighed before and after each processing station using a balance. Based on the mass method, the average total wood recovery rate was 26.2% ± 2.3%. For individual products and per station, the significant difference in the wood recovery rate occurred only at the resawing and edging, and trimming stations. The relationship between the teak quality, product dimensions, and type of finish was significantly different, where A-quality teak, large dimensions, and polyurethane finish resulted in a higher wood recovery rate. Both methods were reliable because of insignificant differences in the wood recovery rates. However, the mass method was more efficient and practical. The proposed protocol using the mass method is a suitable and effective system because the contribution of the variance component of the method was 2.71%.