Volume 10 Issue 1

This research aimed to study the effect of lignin, natural rubber latex (NRL), nanocellulose, and talc on production of biobased foam using cassava starch as matrix. Comparison study on lignin extraction from sugarcane bagasse (SCB) for different types of base (KOH and NaOH), concentration (10 %w/w and 40 %w/w), and temperatures (60 °C for 3 h and 120 °C for 1 h) was performed. The most suitable isolation condition giving the highest yield of lignin and lowest hemicellulose contamination was 40 %KOH at 120 oC for 1 h. A mechanical method was superior to a chemical method for cellulose size reduction owing to more appropriate size distribution and uniformity of nanocellulose. The most favorable proportion of foam contained 20% nanocellulose, 3% talc, 0.1% NRL, 38.5% water, and 76.9% crosslinked cassava starch. These conditions resulted in favorable flexural strength, modulus, and percentage of elongation, analogous to polystyrene foam. An appropriate amount of added lignin increased the elasticity of biofoam.

The dynamic wettability of plasma-modified poplar veneer was investigated with sessile adhesive droplets using a wetting model. Dynamic contact angle, instantaneous and equilibrium contact angles, and their rates of change (K-value) were used to illustrate the dynamic wetting process. The experiment consisted of selecting treatment parameters (type of gas, power) that would lead to the increased wettability of wood. Three resin systems, urea-formaldehyde (UF), phenol-formaldehyde (PF), and diphenylmethylene diisocyanate (MDI), were evaluated. Based on the wetting model, the K-value was used to interpret the kinetics of wetting. The higher the K-value, the faster the contact angle reaches equilibrium, and the faster the liquid penetrates and spreads. Therefore, the model was helpful for characterizing the dynamic wettability of wood surfaces modified with different plasma treatments. The K-values of plasma-treated veneer surfaces at different plasma power levels and with different gases (such as O2, N2, Ar, air, and NH3) were 458% to 653% and 332% to 528% higher than those of untreated veneer surfaces, respectively. In addition, the K-values of the three resins on the oxygen plasma-treated veneer surfaces were 38% to 1204% higher than those on the untreated veneer surfaces. Therefore, this method was helpful for characterizing the dynamic wettability of veneer surfaces modified with plasma treatment.

Oil palm leaf fiber was used as a reinforcement material for the preparation of polypropylene composite. First, the influence of fiber loading on the mechanical and thermal characteristics of the composite was investigated. Epolene® E-43 was used as a compatibilizing agent to enhance the mechanical and thermal properties as well as the morphology of the oil palm leaf fiber/polypropylene composite. The composites were prepared with 10, 20, 30, 40, 50, and 60% ratios of fiber by melt blending technique using internal mixer machines and compressing molding. The addition of fiber led to an increase in the tensile and flexural properties of the composite in comparison to virgin polypropylene. Similarly, Epolene® E-43 was found to improve all the studied properties. Water absorption increased with increasing fiber loading; however, the addition of Epolene® E-43 reduced this property. According to Fourier transform infrared spectroscopy results, interactions between the components of the composite were physically indicated for all fiber content ratios, except 20% due to more interaction between the components. Dynamic mechanical analysis (DMA) showed that the presence of the oil palm leaf fiber enhances mobility but reduces stiffness. The morphological analysis of the composites using a field-emission scanning electron microscope showed that Epolene® E-43 reduced the size and number of voids, which is consistent with the results from the mechanical analysis.

This study examined the influence of cyclic stress on the relaxation speed for native beech wood and laminated wood. Various sample thicknesses were evaluated, and a testing method, which consisted of bending via three-point loading, was developed. The relaxation speed was measured on samples that were cyclic loaded, and the results were compared with those gathered for test samples that were not cyclically loaded. The results show that thicker materials yield a higher relaxation speed. The type of material and the number of loading cycles did not appear to have a significant effect within the measured range of values.

The 3D moldability of veneers, as opposed to the moldability of plastic or other materials, is limited because of the characteristics of wood. By mechanical treatment under appropriate conditions, it is possible to partially modify veneer characteristics. In this study, the intention was to determine the effect of factors influencing the 3D moldability of veneers. Therefore, this study was focused on determining the 3D moldability of veneers with square and circular shape, which were stressed under six moisture content levels (i.e., 0%, 8%, 16%, 20%, 30%, and 100%). To determine the influence of wood species, the results for beech veneers of 0.5-mm thickness were compared to the results for birch veneers of 0.5-mm thickness. These sets of samples were stressed with a spherical stamping tool with three different radii of curvature (i.e., 20, 40, and 80 mm). There is currently no standardized method for assessing the 3D moldability of veneers, as opposed to metals (metal sheets). Because of the low moldability of veneers compared to metal materials, Erichsen’s method for assessing the moldability of metal sheets was modified for veneers. The 3D moldability was determined based on maximal deflection of the veneer stressed by the stamping tool before rupture. Based on the established method, the effects of wood species, moisture content of veneers, diameter of stamping tool, and shape of samples on deflection during 3D molding were determined.

The production of dissolving pulp from poplar wood residual slabs was investigated. The residual slab chips were initially prehydrolyzed and subsequently pulped by the kraft process; the resulting brownstock was bleached using a totally chlorine-free (TCF) sequence to full brightness. The pulp contained low pentosans and high α-cellulose content, and the pulp had high reactivity. Its hemicellulose content, reactivity, and degree of polymerization were within acceptable levels for a rayon-grade dissolving pulp. Thus, the residual slabs from poplar can be regarded as a viable raw material for dissolving pulp production. The reactivity of this dissolving pulp was drastically decreased after the xylanase post-treatment, which can slightly lower the pentosans levels. Simultaneously, the crystallinity index of the resulting pulp obviously decreased after xylanase post-treatment.

The effects of lignophenols and pulp fibers as reinforcing elements in biocomposites were studied with poly-(3-hydroxybutyrate) (PHB) biopolymers and polystyrene (PS) matrix materials. Lignophenols and (NH2(CH2)3Si(OC2H5)3) were compared as plasticizing or compatibilizing additives in tests of composite properties. PHB and PP were blended with pulp fiber cellulose and lignophenol by torque rheometer, and the test specimens were processed via injection moulding. Various testing methods, including tensile and impact tests, SEM, XRD, TGA, and ART-FTIR were used to investigate the properties of the composites. PHB and PP-cellulose fiber composites with strong mechanical properties could be created by using a torque rheometer as a mixer at 190 ºC with very short mixing times. The (NH2(CH2)3Si(OC2H5)3) was found to improve the mechanical features of the PP, but not very obviously for both tensile and impact strengths of PHB. However, the lignophenols positively affected the PHB-pulp fiber composites. In summary, a novel method has been demonstrated for creating biodegradable composites with pulp fibers in the absence of a coupling agent, and lignophenols may be applicable as an additive in the cases described in this study.

The objective of this work was to evaluate some of the important physical and mechanical properties of experimental oriented strandboard panels manufactured from four different cultivars of date palm (Phoenix dactylifera) fronds. Currently date fronds are considered as waste and under-utilized. Open burning and landfill are common practices for such resources. Therefore experimental panels were manufactured from strands washed with water to determine the effect of such treatment on panel properties. Bending characteristics, internal bond strength, thickness swelling, water absorption, and linear expansion along and across the grain orientations of the samples were tested. Based on the findings in this work, the internal bond strength values of the samples were found to be satisfactory. However, the samples manufactured from water-soaked strands had lower mechanical and physical properties as compared to those made from unwashed material. Water treatment also adversely influenced dimensional stability, namely thickness swelling, water absorption, and linear expansion of the samples. It appears that untreated date palm fronds as underutilized resource show promise sustainable raw material for the manufacture of oriented strandboard panels, but further research is required to maximize their potential.

This work compares the effectiveness of local reinforcements of pine beams. Test beams were reinforced with carbon fiber reinforced polymer (CFRP) tape and layered laminate bamboo composite (LLBC) plates. The effective length of local reinforcement reached 5% of the entire beam length. Beams were tested to determine static bending strength in accordance with the EN-408 (2012) standard. On the basis of testing and calculations, it was concluded that local reinforcement with both reinforcing materials caused a significant (p < 0.05) gain in load capacity and modulus of elasticity. The LLBC, which has a tensile strength 25 times lower and a modulus of elasticity 17 times lower than CFRP, resulted in the highest load capacity. This phenomenon is related to the more uniform stress distribution on the composite with LLBC plate – glue bond – wood layers and lower strain within the bond in comparison to the CFRP reinforcement. Therefore, critical stresses within the bond were not exceeded, which often happens in reinforcement with materials of high modulus of elasticity (such as CFRP tape).

Pellets may be produced with different types of agriculture or forestry crops in Costa Rica. This work evaluated the energy, physical, and mechanical properties of pellets fabricated from 12 types of agricultural and forestry crops (Ananas cumosos, Arundo donax, Coffea arabica, Cupressus lusitanica,empty fruit bunch and oil palm mesocarp fiber of the fruit of Elaeis guineensis, Gynerium sagittatum, Pennisetum purpureum, Phyllostachys aurea, Saccharum officinarum, Sorghum bicolor,and Tectona grandis), and similarities among these crops were established by multivariate principal component analysis. High variation was found in the pellet properties. The energy evaluation revealed that C. lusitanica and P. aurea are the crops with the best qualities for fuel use because of their high calorific values (from 16807 kJ/kg and 19919 kJ/kg, respectively) and low ash content (1.03% and 3.39%, respectively). As for physical properties, most crops exhibited values within the range noted by several authors and standards. All 12 pellet crops displayed high durability (from 72.12% to 92.98%) and compression force (from 295.18 N to 691.86 N). Moreover, the evaluation of crop similarities allowed the determination of four group combinations. Within these groups, C. lusitanica, P. aurea, and G. sagittatum had similar energy qualities and the best caloric characteristics.