Research Articles

Wood flour, PLA, and other additives were mixed evenly in a high speed mixing machine. The granules were prepared by melt blending and extrusion granulating with a twin-screw extruder, and test specimens were molded by a plate curing machine. By changing the heating temperature, the molding pressure, the holding pressure time, and azodicarbonamide (AC foaming agent) contents, the influences of four factors on the apparent density, the mechanical properties, and the morphology of the biodegradable foamed WPCs were investigated. The best processing parameters and the optimum AC foaming agent content were obtained. When heating temperature was 178 °C, heating time was 10 min, holding pressure time was 25 s, and molding pressure was 7 MPa, the test specimen was lighter in color, with a smooth surface and dense, uniform cross section. The mechanical properties (flexural strength and impact strength) of the foamed WPCs were relatively good. When adding 1% AC foaming agent, the foamed WPCs showed uniformly distributed microcellular structure, and the average pore diameter was about 67 µm. The density was reduced by 18.6%, and the flexural strength and impact strength were increased by 128.6% and 40%, respectively, compared with non-foamed WPCs.

Chemical modifications have been widely adopted for improving the dispersibility of cellulose nanocrystals (CNCs) in nonpolar matrixes. Nonetheless, an engineering design for improving the CNC structure is still challenging due to the differences in the dispersion level of CNCs depending on the modification strategies in a desired matrix. The current study was conducted to find an appropriate functionalization technique for CNCs and an effective manufacturing process for CNC-polypropylene (PP) nanocomposites. The surface structures of CNCs were successfully changed using toluene diisocyanate (TDI) and maleic anhydride grafted PP (MAPP). The tensile properties and thermal stability of the nanocomposites with MAPP grafted CNCs were higher than those of pristine and TDI grafted CNC systems. A melt-extrusion process with pre-dispersion processing exhibited more positive effects on the properties of the nanocomposites in comparison to the systems without pre-dispersion. Scanning and transmission electron microscopes also provided clear evidence of the dispersion levels of unmodified and modified CNCs in the PP matrix.

The growing consumption of tender coconut water in Brazil has resulted in a generation of green husk, which in turn has led to pollution, as it takes eight to ten years to degrade. With the objective of finding applications for these fibers, the characterization of their chemical composition, tensile properties, and structural properties is presented in this paper. The density of the green fibers was 1200 kg/m3, and the diameter ranged between 272 μm and 513 μm. The length of the ultimate fibers was 940 μm, while the cell wall thickness and size of lumen were approximately 3.6 μm and 11.8 μm, respectively. The crystallinity index, ultimate tensile strength, Young’s modulus, and elongation of the lignocellulosic fiber were 48%, 114 MPa to 159 MPa, 1.20 GPa to 1.96 GPa, and 41% to 44%, respectively. These results were compared with previously published results of both green and brown coir fibers with the purpose of exploring the addition of value to this abundant agro-industrial residue.

The physical-mechanical properties of bamboo-polyethylene composites (BPCs) change depending on the environmental temperature and exposure to moisture during outdoor use. In this study, the water absorption, density, mechanical properties, and wear rate of the composites were tested after immersion in water, and four water temperatures were examined. Bamboo charcoal (BC) was used to improve the properties of the BPCs after hydrothermal aging. The composites were improved because of the strong interfacial interactions between the BC and polymers. The experimental results showed that the water diffusion rate accelerated as the water temperature increased. The BC reduced the water absorption at all of the water temperatures and the diffusion coefficient at temperatures above 39 °C. The wear rate of the composites first increased, and then decreased as the water temperature increased. The density and flexural properties decreased with an increased hydrothermal aging temperature. Overall, hydrothermal aging decreased the water resistance and mechanical properties. Additionally, these effects were enhanced as the water temperature increased, but were countered by the incorporation of the BC.

The toughening of wood-plastic composites (WPC) based on silane/ peroxide macro crosslink poly(propylene) (PP) systems was studied. A 23 experimental design was adopted to initially optimize three parameters: silane, wood flour, and talc contents of the WPC formulation. The WPCs were manufactured on a co-rotation twin screw extruder. Test specimens were prepared via injection molding. The WPC compounding formula with 8 phr of silane, 35 phr of wood flour, and 20 phr of talc was used to study the effect of ultra-high molecular weight polyethylene (UHMWPE) as a toughener. The impact strength was improved up to a 10-phr UHMWPE loading. The flexural properties and heat distortion temperature (HDT) slightly decreased. When exceeding 10 phr of UHMWPE, the unmelted UHMWPE agglomerated and the mechanical properties were inferior. The fiber/matrix interfacial adhesion was enhanced by the sauna treatment. A marginal increase in the fracture toughness was observed. The impact strengths increased with the addition of ethylene propylene diene terpolymer (EPDM) as a rubber toughener. However, high EPDM contents caused a decrease in the HDT. The sauna incubation of the EPDM-toughened WPC enhanced the impact strengths. The EPDM effectiveness was determined by the better PP matrix toughness and UHMWPE/PP interfacial adhesion.

The aim of this study was to investigate the potential of Typha latifolia L. stem and leaf powder (T-SLP) to remove methylene blue (MB), a cationic dye, from aqueous solutions. The T-SLP was used without any modification. The batch adsorption experiments were carried out at 25 °C under varying operating parameters, namely pH, initial concentration, contact time, and adsorbent dose. Equilibrium isotherms and kinetics were used for data analysis. The surface morphology of the adsorbent and the possible interactions between the T-SLP and MB were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR), respectively. The experimental data fitted well to the Langmuir model, with a maximum adsorption capacity of 126.6 mg g-1. The efficiency of dye removal in the substrate was high, reaching a maximum value of 98.69%. Intra-particle diffusion was involved in the adsorption process, and the pseudo-second-order kinetics was the best fit for the adsorption of MB onto T-SLP, with a high correlation (R2 ≥ 0.9993) for all initial MB concentrations studied. The results of this work revealed that T-SLP can be used as a potential alternative for the rapid removal of MB from aqueous solutions.

To improve nitrogen fertilizer efficiency and minimize the negative impact of nitrogen fertilizer on the environment, a novel three-dimensional network polymer material with slow release character was prepared based on hydroxymethylated lignin (HML) and urea/hydroxymethylurea/urea-formaldehyde polymers (U/HU/UF) through solution polymerization. The novel material (Lignin-U/HU/UF) was characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance spectra (1H NMR), and distortionless enhancement by polarization transfer analysis (DEPT 135). The N release characteristics of the material were determined by soil leaching experiments under laboratory conditions. On this basis, the release profiles of total nitrogen and other nitrogenous compounds (NH4+ and NO3-) were investigated. The experimental data showed that lignin can be used as a majority component in material, which trapped polymers such as urea, hydroxymethylurea, and urea-formaldehyde to improve slow-release properties of fertilizer. The results indicated that the eco-friendly material (Lignin-U/HU/UF) with good controlled-release capacities potentially could be applied in agriculture and horticulture.

Silver nanoparticles (AgNPs) have been applied as an antifungal agent, which results in AgNPs contamination of agricultural waste that interferes with the lignocellulosic enzymes produced by fungi. Therefore, this study examined the production of carboxymethylcellulase (CMCase) and manganese-dependent lignin peroxidase (MnPase), using barley straw treated with AgNPs. Trichoderma asperellum growth was not inhibited at 25 ppm AgNPs, while negligible growth inhibition was observed at 50 ppm AgNPs, which was not observed with Aspergillus terreus and Curvularia lunata. T. asperellum was the highest producer of CMCase and MnPase using barley straw with or without 25 ppm AgNPs versus A. terreus or C. lunata. AgNPs addition to barley straw before T. asperellum inoculation played a role in repressing enzyme activities (CMCase 156.33 U/mL and MnPase 1.28 U/mL); however, addition of AgNPs (50 ppm) after 10 days of incubation showed the highest activity (CMCase 160.67 and 1.35 U/mL MnPase). Optimum temperature for enzyme production by T. asperellum using untreated and treated barley straw was 35 °C and 30 °C, respectively. Enzyme activities increased with increasing polyoxyethylenesorbitan monooleate surfactant concentrations up to 0.25 mL/g substrate without AgNPs, whereas the activity decreased with AgNPs (25 ppm). The exception to this observed trend was at low concentrations of the surfactant (0.10 mL/g substrate).

It is necessary to know the type and quantity of wastes to select the proper applications and waste management strategies. This study investigates the type, quantity, and utilisation methods of wastes generated by micro-sized enterprises that produce timber and furniture, which are two major sub-sectors of the forest products industry in Trabzon. A total of 885 enterprises of manufacturing timber and furniture in Trabzon were identified by reviewing the records from the professional chambers of commerce. The stratified sampling method was used to compare the sub-sectors, and the sample size was determined as 120. Among these, 70 furniture- and 50 timber-producing enterprises were interviewed. The chi-square test was used to determine whether the applications of timber and furniture enterprises are dependent on each other. In general, there are no differences in waste utilisation applications and education level between the sub-sectors. The percentage of the owners/managers that received any vocational training is 77.5% in two sub-sectors. In general, engineered wood wastes are used as fuel. The majority of the owners/managers in the timber industry believe that their waste has an economic value compared to those in the furniture sector. The total amount of wood waste generated by sectors was 528 tons in a month.

Machinability issues during drilling of wood-based materials were evaluated. Three types of standard wood-based materials of substantially different internal structures, i.e., fibreboards, particle boards, and veneer boards, were selected as test samples. The experiment consisted of drilling holes through samples made of 14 different materials. The purpose of the experiment was to determine the quality of the edges of the holes and to evaluate values of the cutting force and torque. The obtained results were used to determine the relative machinability indexes based on the machining quality and cutting forces. These indexes were defined by referencing the obtained data of each tested material to one selected reference material: medium density fibreboard. The experimental data showed that the machinability index based on the quality criterion was not correlated with the index based on the cutting force criterion. The quality index was not correlated with the basic, routine parameters of wood-based boards. However, the cutting forces index sometimes showed a significant correlation of this type. The quality index showed the influence of the internal structure and homogeneity of the different types of materials.