Volume 13 Issue 3

9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) graft γ-amino propyltriethoxy silane (APS), γ-glycidoxy propyltrimethoxy silane (GPS), and methacryloyl propyltrimethoxysilane (MPS) were synthesized and introduced on the surface of wood fiber. DOPO-g-APS (GPS and MPS) treated wood fibers (DAWF, DGWF, and DMWF) were used to prepare composite phenolic foams (DAWFCPF, DGWFCPF, and DMWFCPF). The chemical structures of DOPO-g-APS (GPS and MPS) were confirmed by Fourier transform infrared (FT-IR) spectra and nuclear magnetic resonance. The structures of DAWF, DGWF, and DMWF were confirmed by FT-IR. The diffraction peak positions were basically unchanged, but the crystallinity was slightly increased. Compared with WF, thermal stabilities were increased. The residue (800 °C) was slightly reduced. Compared with phenolic foam, the properties of DAWFCPF and DGWFCPF were better than others. Besides compression strength, the mechanical properties were increased dramatically, limited oxygen index was slightly enhanced, the cellular pore distribution was more regular, and the size of bubble cell was smaller and more uniform. By comprehensive analysis, the properties of DAWFCPF were best in all samples. The interfacial compatibility was significantly improved between DAWF and phenolic resin. These results confirmed that DOPO-g-APS is a suitable material for treating wood fibers and preparing composite phenolic foams.

Processes of extracting hemicellulose from annual plants usually neglect the cellulose fraction. This study explored the possibility of obtaining both a hemicellulose and a cellulose fraction of sufficient quality for further use, with barley husks used as the raw material. An alkaline extraction was used to isolate the biopolymers by a process in which sodium dithionite replaced the traditional sodium borohydride as the reducing agent. The cellulose fraction was successfully transformed into nanocellulose by sulfuric acid hydrolysis, and the obtained hemicellulose (i.e., arabinoxylan) displayed carbohydrate composition characteristics similar to those previously reported in the literature for processes of extracting hemicellulose from barley husks. Using this methodology, both the cellulose and hemicellulose can be isolated in high quantities of dry material and used for transformation into new bio-based materials.

In this study, a bamboo-derived magnetic carbonaceous solid acid catalyst (BC@Fe3O4@SO3H) was synthesized by FeCl3 impregnation, which was followed by incomplete carbonization and -SO3H group functionalization. FT-IR, XRD, and TGA results showed that the prepared catalyst contained -SO3H, -COOH, and phenolic -OH groups. It exhibited poor adsorption ability for the dominating sugars released during the catalytic conversion process. The prepared bamboo-derived magnetic carbonaceous solid acid presented high catalytic activity for depolymerization and conversion of corncob hemicellulose. Warm water immersion under 60 °C was able to destroy the complex corncob cell wall structure and accelerated the dissolution of carbohydrates. The highest furfural yield of 54.1 mg/g was obtained from 40 °C water-immersed corncob after reacting at 180 °C for 30 min. Up to 96.1% of the corncob hemicellulosic backbone sugars were depolymerized to monosaccharides and oligosaccharides in the hydrolysates. The prepared catalyst exhibited a simple magnetic recovery process and high stability. This work provides promising strategies for biomass utilization via renewable materials.

The effect of sugar palm fiber (SPF) loading was studied relative to the mechanical properties of roselle (RF)/SPF/thermoplastic polyurethane (TPU) hybrid composites. RF/SPF/TPU hybrid composites were fabricated at different weight ratios (100:0, 75:25, 50:50, 25:75, and 0:100) by melt mixing and hot compression. The mechanical (tensile, flexural, and impact test) and morphological properties of tensile fractured samples were examined using a universal testing machine, impact machine, and scanning electron microscope. It was found that the hybridization of RF/SPF increased its impact strength corresponding to the increases in the SPF content of the composites. The tensile and flexural properties of the hybrid composites decreased due to poor interfacial bonding between the fiber and matrix. Scanning electron micrographs of the tensile fractured surface of the RF/SPF hybrid composites revealed fiber pullouts and poor adhesion bonding. In conclusion, the hybridization of SPF with RF/TPU composites enhanced its impact strength while decreasing the tensile and flexural strength.

Understanding and mastering the color change of wood during heat treatment is essential in the wood working industry because it saves time and reduces energy costs. An artificial neural network (ANN) was employed in this study to establish the relationship between the process parameters of heat treatment and the color change of wood. Three important parameters: temperature (180 °C, 190 °C, 200 °C, 210 °C, and 220 °C), treatment time (2 h, 4 h, 6 h, and 8 h), and wood species (larch and poplar) were considered as inputs to the neural network. There were four neurons in the hidden layer that were used, and an output layer as wood color. According to the results, the mean absolute percentage errors were determined as 0.53%, 0.65%, and 0.31% in the prediction of color change color (ΔE) values for training, validation, and testing data sets, respectively. Determination coefficients (R2) greater than 0.99 were obtained for all data sets with the proposed ANN models. These results showed that ANN models can be used successfully for predicting the color changes in wood during heat treatment.

Wood is a renewable and environmental friendly material, but its low dimensional stability characteristics limit its applications. In this study, wax mixed with dimethyl silicone oil was used to enhance the dimensional stability under heat treatment. Samples were heated at 120 °C under 3 impregnation conditions (wax, wax + 20% dimethyl silicone oil, and wax + 40% dimethyl silicone oil) for 3 and 6 h respectively. After treatment the effects of combination pretreatment on wood weight gain percentage (WPG), tangential, radial and volume swelling coefficients (TS, RS, VS), distribution of impregnation liquid, and the types of functional groups of African Padauk (Pterocarpus soyauxii) were evaluated. The results showed that impregnation improved the dimensional stability of wood to a certain extent; moreover, the addition of dimethyl silicone oil improved the modification effect. Furthermore, the VS reduced to 0.66 (±0.28)% in the treatment of wax + 20% dimethyl silicone oil for 6 h. The impregnation liquid mainly adhered to the walls of vessels and ray cells. The hydroxyl absorption intensity of the impregnated groups was lower than that of the control group.

During the last decade, the Slovak and Croatian furniture industry markets have experienced changes that have made these markets more interesting for domestic and foreign investors. Furniture manufacturers and retailers are still trying to determine the best ways to adjust to customer demands, and understanding the furniture preferences of customers would provide beneficial information to the furniture industry. The purpose of this study, which was conducted in 2016, was to improve the knowledge regarding differences in the preferences of customers for furniture materials, attributes, and styles when purchasing furniture in Slovakia and Croatia. The findings showed that Slovak and Croatian respondents differ in their preferences for furniture materials, as well as the factors that influence their purchasing decisions when buying interior and exterior furniture. Overall, it was found that wood as the furniture material, compared with the surveyed substitutes, was widely preferred among the Croatian and Slovak respondents.

Current approaches to human resource management are focused on the sustainable development of small and medium-sized enterprises (SMEs). Career strategies of employees are its integral part. The aim of this paper is to determine the changes in professional priorities of employees in small and medium-sized wood-processing enterprises in the area of motivation relating to career aspiration throughout the course of life. The research outcomes show significant correlation between age, gender, and motivation factors relating to career aspiration. Slovak women working in SMEs prefer motivation factors relating to finances, mutual relationships, work, and career aspiration. Motivation factors selected by men are almost the same. In terms of age, motivation factors relating to career aspiration are preferred mainly by women aged 30 to 40 years old. Mentioned factors become less important for respondents of older age groups. Men working in SMEs prefer the motivation factors relating to career aspiration at the age of 30 and subsequently they become less important as well. Following the outcomes of this research, managers of SMEs should motivate career-oriented employees especially according to their needs. In the long-term perspectives, managers can encourage employees to stay focused on their careers.

Chitosan-cellulose film is found in food processing and biotechnology because of its biocompatibility, biodegradability, and antibacterial property. Despite the excellent properties, the presence of intramolecular and intermolecular hydrogen bonds cause cellulose and chitosan to be insoluble in common solvents, resulting in limited mechanical strength. Graphene oxide has heavy oxygen-containing functional groups with excellent mechanical properties, which makes it an ideal filler for reinforcing polymers. In this work, blends of graphene oxide and chitosan-cellulose were successfully produced using 1-ally-3-methylimidazolium chloride ([Amim]Cl) and dimethyl sulfoxide (DMSO) as solvent media. Films were prepared by phase-transfer method and investigated by Fourier transform infrared analysis, scanning electron microscopy, atomic force microscopy, X-ray diffraction, thermogravimetric analysis, and mechanical tests. The absence of the bands corresponding to C=O stretching in graphene oxide and the -NH bending of amides and amines in chitosan, the absence of the diffraction peak at 2θ =11.3° in graphene oxide (XRD), and the improvement of thermal stability and mechanical property provided evidence for the interaction between graphene oxide and chitosan-cellulose.

NH4Cl was used to optimize the pretreatment conditions for biomass pretreatment to improve enzymatic saccharification and hemicellulose degradation of eucalyptus chips. After pretreatment, the solid substrate (SS) and pretreatment liquor (PL) were characterized, and the SS was enzymatically hydrolyzed to detect the conversion yield of cellulose (CYC). For the pretreatment using NH4Cl, the removal rate of hemicellulose reached up to 100% in some cases, but a great proportion of cellulose remained in the SS. The optimized conditions for pretreatment using NH4Cl were 0.3 M NH4Cl at 200 °C for 25 min. A comprehensive evaluation found that the most suitable severity parameter for pretreatment and enzymatic saccharification was 4.5, although a higher severity parameter could increase the CYC. XRD and FTIR analysis showed that the pretreatment had little influence on the cellulose crystalline region, and the lignin was well-retained in the pretreatment process.