Volume 11 Issue 1

The effect of adding waste polyethylene (WPE) was investigated at various ratios on some physical and mechanical properties of oriented strand board (OSB) panels. All of the test panels were bonded with 6% phenol-formaldehyde resin in three layers. The manufacturing parameters was 0/100, 10/90, 20/80, 30/70, 40/60, and 50/50 by weight% of WPE/wood strand. All the boards were manufactured to achieve targeted specific gravity of 0.65 g/cm3. Polyethylene improved the water resistance of the OSB panels because of its hydrophobicity. Based on the results of this study, thickness swelling, humidity, dimensional stability, water absorption, and screw withdrawal resistance of the samples were improved significantly. However, MOE, MOR, and internal bond strength values of the samples decreased with increasing WPE in the panels when compared to the control panels but met minimum requirements in EN 300 (type 1-2-3-4) control panels. The conclusion was reached that waste polyethylene can be used in the manufacture of OSB panels, resulting in the enhancement of above mentioned physical and mechanical properties, as well as a safe disposal and economical utilization.

A simple and inexpensive method for producing water-stable pulp fibre yarns using a deep eutectic mixture composed of choline chloride and urea (ChCl/urea) was developed in this work. Deep eutectic solvents (DESs) are eutectic mixtures consisting of two or more components that together have a lower melting point than the individual components. DESs have been previously studied with respect to cellulose dissolution, functionalisation, and pre-treatment. This new method uses a mixture of choline chloride and urea, which is used as a swelling and dispersing agent for the pulp fibres in the yarn-forming process. Although the pulp seemed to form a gel when dispersed in ChCl/urea, the ultrastructure of the pulp was not affected. To enable water stability, pulp fibres were crosslinked by esterification using polyacrylic acid. ChCl/urea could be easily recycled and reused by distillation. The novel process described in this study enables utilisation of pulp fibres in textile production without modification or dissolution and shortening of the textile value chain. An interdisciplinary approach was used, where potential applications were explored simultaneously with material development from process development to the early phase prototyping.

This research analyzed the motivating and demotivating factors amongst employees in a wood processing and furniture manufacturing company. Research was conducted over the year 2010, during the time of a full economic crisis and before the restructuring of the company was done. Analysis also was conducted in 2014, during the beginning of the economic recovery and after the restructuring of the company. Research was conducted with a survey using a questionnaire containing six questions with multiple choice statements. The questions were closed-ended, and respondents used the Likert four-level scale of importance for each statement. A total of 180 employees were surveyed, and results were statistically processed by using the χ2- test and cluster analysis. This study established that the motivation factors most important to employees in a company are significantly different during the time of an economic crisis, and in the period of economic recovery, i.e. before and after restructuring of the company. Employees were most concerned about physiological needs in the time of a crisis, whereas in the time of an economic recovery, employees consider social needs to be of more importance. Also, employees consider psychological circumstances of work to be more important in the year 2014 than in the year 2010. Employees’ overall motivation can be linked to higher efficiency and higher quality production and business results, and such research should be conducted more often.

The objective of this project was to use sucrose as a partial substitute for melamine in the synthesis of sucrose–melamine-formaldehyde (SMF) resin. The SMF was synthesized in a base condition. The wet bonding strength, shelf life, and formaldehyde emission of the SMF resin were determined. Fourier transform infrared spectroscopy (FT-IR) and mass spectroscopy (MS) were employed to analyze the chemical structure of the SMF resin. The shelf life of SMF resin increased as the sucrose content increased. Also as the sucrose content increased, the wet bonding strength decreased and the formaldehyde emissions decreased. The FT-IR and MS spectra revealed the structures of sucrose, melamine, and formaldehyde in the SMF, and chemical reactions of SMF resins occurred between the three primary hydroxyl groups of sucrose and methylolmelamine. Based on the results of this study, a sucrose to melamine mole ratio of 0.4:1 was determined to be the optimal ratio for the SMF resin.

During industrial wood grinding, logs are pressed against a rotating stone, with the logs and fibre axes parallel to the axis of the stone. For this study, wood blocks were fed into a laboratory grinder with various alignments in relation to the surface of the grinding stone. The effects of the alignment on the properties of the pulp, the amount, and the quality of the fines were measured, and a grinding mechanism is proposed. In this paper, the obtained results showed that the pulp quality was highly sensitive to the angle between the stone surface and the log, and different for fatigue-based and force-based grinding. The tests were observed using microscopic techniques and discussed in terms of fines amount and fines quality. In gentle refining, the fibre structure is loosened by fatigue before it is bent on the surface, pressure pulses produce fibrillar material, and fibres develop good bonding ability. In forced grinding, the process is “violent” and the fibre wears and is crushed immediately on the surface into small particles with low bonding ability.

The production of functionalized polymers from biomass is of great interest. Cellulose nanofibrils (CNFs) isolated from lignocellulose have great potential in novel functional materials. In the present study, mild enzymatic treatment followed by high pressure microfluidization of a bleached softwood kraft pulp led to the release of individualized CNFs. Disk milling and high pressure microfluidization resulted in entangled networks of CNFs. CNFs from mild enzyme pretreatments were 8 to 12 nm in diameter and 200 to 400 nm in length, while CNFs from pure mechanical pretreatment were an entangled network of nanofibrils with a diameter of 10 to 20 nm. Films prepared from the resulting CNFs were flexible and semitransparent, and they exhibited high specific tensile stress and modulus. The specific tensile stress and modulus were increased by 3- to 5-fold and 5- to 11-fold, respectively. The specific tensile modulus of the CNFs films from mild enzyme treatments followed by microfluidization was approximately 15 to 16 MN·m/kg, while that of CNFs from pure mechanical fibrillation with or without microfluidization was 10 MN·m/kg and 14 MN·m/kg, respectively. The specific tensile strength of the CNFs films from mild enzyme treatment was slightly lower (72 to 98 kN·m/kg) than that of the CNFs films from pure mechanical fibrillation.

Alkali-pretreated sugarcane bagasse fiber was subjected to fed-batch simultaneous saccharification and fermentation (SSF) with a pre-hydrolysis process to increase the solids loading and produce a high concentration of ethanol. The hydrolysis medium and yeast feeding modes were investigated to determine suitable conditions for high sugar yield and ethanol production. Batch addition resulted in a cumulative substrate concentration of up to 36% (w/v) and enhanced ethanol concentrations, while ethanol conversion efficiency gradually declined. Enzymatic pre-hydrolysis and fermentation with fed-batch mode contributed to the SSF process. The highest ethanol concentration was 66.915 g/L with the conversion efficiency of 72.89%, which was achieved at 30% (w/v) solids content after 96 h of fermentation. Hydrolyzed medium and yeast were added in batch mode at 24 h of enzymatic hydrolysis and fermentation, respectively. Thus, combining the fed-batch mode with pre-hydrolysis SSF produced a high yield of ethanol.

Natural defects, especially knots, on the surface of veneers have a great influence on the sorting and degradation of veneers. To realize rapid and accurate knot detection, a study on the possibility of detecting knots was carried out. Samples of poplar, eucalypt, and masson pine were used. The experiments mainly focused on the ability of using the models built with samples from one type of knot and normal wood to predict samples from a different type of knot and normal wood within the same wood species; and when only the samples from middle-sized knots and normal wood were used, whether or not the model based on one species could predict the samples from another species. The results showed that using the model built with small knots and normal wood to predict the larger knots and normal wood was not satisfactory, but the model based on large knots and normal wood can predict the samples from smaller knots and normal wood under a certain condition. When only the middle-sized knots and normal wood from the three species were used, the model built with eucalypt samples could predict the samples from poplar, and vice versa; however, the model built with masson pine samples could not predict the other two sample species, and vice versa.

In arid and semi-arid areas, organic matter decomposition is stimulated by ultraviolet radiation. In this paper, the association between straw decomposition and UV-A exposure was evaluated. Oven-dried rice straw samples were chronically exposed to UV-A radiation and examined periodically for up to 90 days at room temperature. Scanning electron microscopy (SEM) showed that noticeable disintegration of the fiber structure occurred on the irradiated sample surface in comparison to the control. At the end of the UV-A treatment period, straw mass had decreased by 5%, and dissolved organic carbon (DOC) increased by 18%. The content of cellulose, hemicellulose, and lignin of the irradiated straw decreased by 29.3%, 14.4% and 49.3%, respectively. The marked loss of nitrogen and potassium in the exposed straw were also observed. Thermogravimetric analysis (TGA) showed that treatment with UV-A radiation tended to decrease the mass loss rate and the thermal degradation temperature of the straw biomass from 220 °C to 208 °C. Infrared spectrometric analysis (ATR-FTIR) showed that functional groups, e.g., C–OH and C–O–C, were disrupted obviously due to UV-A exposure. These results suggest that ultraviolet-A irradiation facilitates straw decomposition by direct photochemical degradation.

Using response surface methodology, the pretreatment conditions of kenaf fibers were optimized to improve the tensile strength of kenaf phloem insulation cotton (KPIC). The effects and interactions of three parameters—sodium hydroxide concentration (X1), soaking time (X2), and beating time (X3) —on the tensile strength of the kenaf fibers were investigated. The Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and thermal conductivity of the KPICs further confirmed the validity of the optimal pretreatment conditions. Sodium hydroxide concentration had the greatest effect on kenaf fibers. The maximum tensile strength of 117.6 N resulted from a sodium hydroxide concentration of 4%, soaking time of 50 h, and beating time of 12 min. As shown by FTIR and XRD, optimized pretreatment generated surface functional groups and increased the tensile strength of fibers. It has a low thermal conductivity of 0.032 W/mK. In conclusion, the pretreatment of kenaf fiber significantly improves the tensile strength of KPIC and also improves the retention rate of the chemicals used during the preparation of KPIC. As an environment friendly and renewable material, the KPIC has a great application prospect with its good thermal conductivity.