Volume 15 Issue 4

In conventional drying kilns, the drying of especially thick lumber is not ideal in terms of drying quality and drying time. Therefore, it is important to dry thick and dense lumber by high-frequency electromagnetically heated vacuum drying. In this study, common oak (Quercus robur) and common walnut (Juglans regia) selected from local sources used in rifle stock were used as experimental material. These materials were technologically examined by drying the timber for a short time using a fully automated, high frequency vacuum (HF + V) drying kiln. Physical and mechanical properties of these tree species were compared after air drying and HF + V drying processes. There were no significant changes in physical properties. However, the mechanical properties such as bending strength, modulus of elasticity, compression strength, and dynamic bending strength were decreased. According to these results, non-overloaded areas like rifle stock can use high frequency vacuum drying as the preferred drying method compared to conventional drying methods.

International markets for U.S. forest products continue to make a significant contribution to the national economy; sustaining growth in production and job creation as demand from domestic markets is still yet to match that observed during the early 2000s. In this context, industry, government, and academia remain focused on procuring better market shares in foreign markets. The goal of this research is to help hardwood mills to improve their understanding of the needs of potential clients abroad and thus helping them to develop a competitive advantage. An exploratory study based on text mining of questionnaire data was conducted following a competitive criteria-based model on the major foreign markets for U.S. hardwood products. From a sample of buyers attending trade shows in Asia and Europe, this work has identified a series of factors for manufacturers to consider in future export ventures. It was determined that price and quality play multiple roles in developing a competitive advantage. Color-consistency and an adequate stock of the right mix of species are considered minimum requirements to compete in those markets. In contrast, certain time-compression dimensions are perceived as opportunities to add value and, therefore, to stay ahead of the competition.

The application of cellulose hybrid biocomposites filled with calcium carbonate has attracted wide attention in packaging and other fields in recent years. In this study, regenerated cellulose (RC) films filled with calcium carbonate were successfully prepared by dissolution, regeneration, and in situ precipitation of CaCO3. The optical, mechanical, physical, and chemical properties of biocomposites were examined by UV-visible spectroscopy, tensile testing, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analyses (TGA). The results showed that RC films with different CaCO3 contents exhibited good flexibility, optical properties, mechanical strength, and thermal stability. The RC biocomposite filled with calcium carbonate showed a tensile strength of 84.7 ± 1.5 MPa at optimum conditions. These RC biocomposites filled with CaCO3 may find application in packaging.

Composite nanofibre polyvinyl alcohol (PVOH) was prepared in this work reinforced with nanofibrillated cellulose (NFC) using an electrospinning technique. NFC was isolated from oil palm empty fruit bunches (OPEFB) by steam explosion method followed by acid hydrolysis. A 12 wt% PVOH solution in distilled water was prepared under constant reflux at 80 ºC for 5 h. Several concentrations of NFC were added to the polymer solution of 2.5, 5.0, and 7.5 wt%. The nano-dimension of NFC was analysed using transmission electron microscopy (TEM). The morphology of electrospun nanofibre was characterised using scanning electron microscopy (SEM). The morphology of PVOH nanofibre was smooth and uniform without beads. The presence of NFC in the PVOH nanofibre decreased the diameter. The morphology of PVOH/NFC nanofibre at a concentration of NFC 2.5% was fairly uniform with good quality. However, the preparation of PVOH/NFC nanofibre at concentrations of NFC 5.0% and 7.5% resulted in elliptical beads. The crystallinity of NFC and electrospinning nanofibre was investigated using X-ray diffraction (XRD). In addition, the thermal properties of the samples were analysed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results showed that NFC improved the thermal stability of electrospun PVOH nanofibre.

Zeolite was investigated as a potential component in the production of medium-density fiberboard (MDF). A mixture of beech (40%), oak (30%), and pine (30%) wood chips was used for fiber production. Chips were cooked for 4 min in an Asplund defibrator with a vapor pressure of 8 bar, and a temperature of 180 °C. Chemicals were added on fibers in the blow line. The resins were added at 11 wt% based on oven-dried wood fibers. Ammonium sulphate was added at 0.72 wt% based on resins. Paraffin wax was added as 1.8 wt% based on resin. Zeolite was prepared in a separate tank for its use instead of lignocellulosic fibers in the production of 1 m³ MDF. The fibers were dried to 12% moisture. A temperature of approximately 190 °C and a pressure of approximately 32 kg.m-² were applied to the mixture for 280 s to make MDF panels (500 x 490 x 14 mm). Mechanical properties of MDF boards were significantly increased for bending (MOE) and elastic modulus (MOR), but a little negatively affected on internal bond (IB), physical properties were negatively increased thickness swelling (ThS) and water absorption (WA). Consequently, increasing zeolite minerals in MDF boards showed best results of formaldehyde emission properties of MDF.

Recovered hemicellulose fractions from biorefineries have the potential to improve overall process economics during the production of biofuels or other high value chemicals. A common hemicellulose found in many agricultural feedstocks is arabinoxylan (AX). This work investigated the influence of ferulic and p-coumaric acids on the antioxidant capability of AX hemicellulose recovered from sorghum bran, biomass, and bagasse. Sorghum bagasse and sorghum biomass AX contained the largest quantities of bound ferulic and p-coumaric acids at 13.1 mg/100 g and 6.3 mg/100 g, respectively. Antioxidant performance showed that sorghum bagasse AX hemicellulose produced the best reducing capability, while sorghum biomass and sorghum bran AX hemicellulose performed better as free radical scavengers. A reduction in free radical scavenging, as determined by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, occurred for sorghum bagasse and sorghum biomass AX hemicellulose at higher polysaccharide concentrations, which was either caused by the solution properties of the AX hemicelluloses or DPPH reaction reversibility in the presence of phenolic compounds with methoxy content. Alternatively, H2O2 scavenging by the AX hemicellulose revealed a dose-dependent response. Although scavenging effect was reduced at higher concentrations, sorghum bagasse AX hemicellulose functioned as having the best antioxidant capacity with respect to total reducing capability.

As the additive manufacturing process gains worldwide importance, the need for bio-based materials, especially for in-home polymeric use, also increases. This work aims to develop a composite of polylactic acid (PLA) and nanofibrillated cellulose (NFC) as a sustainable approach to reinforce the currently commercially available PLA. The studied materials were composites with 5 and 10% NFC that were blended and extruded. Mechanical, structural, and thermal characterization was made before its use for 3D printing. It was found that the inclusion of 10% NFC increased the modulus of elasticity in the filaments from 2.92 to 3.36 GPa. However, a small decrease in tensile strength was observed from 55.7 to 50.8 MPa, which was possibly due to the formation of NFC aggregates in the matrix. This work shows the potential of using PLA mixed with NFC for additive manufacturing.

To improve the fixed bed and continuous stirred-tank reactor (CSTR) technology relative to the rate of treatment of dairy manure (DM), a continuous stirred tank-treated DM with immobilized carrier biofilm was investigated for 20 days (hydraulic retention time (HRT) was 10 d). Methane productivity, biofilm characteristics, and microbial diversities of the biofilm and digestate were measured. The highest content of extracellular polymeric substances (EPS), proteins, and polysaccharides occurred at 15 days of digestion. An agglomeration phenomenon was observed using a scanning electron microscope on the biofilm. This indicated that the biofilm consisting of EPS was stable during the second HRT. Microbial diversities in digestate and carrier biofilm were characterized using a 16S rRNA sequencing technique. Results showed that the dominant bacterial communities were Pseudomonas (17% to 26%), Clostridium (13% to 21%), and Bacteroidetes (7% to 16%), while the archaea communities were Methanocorpusculum (25% to 37%), Methanosarcina (15% to 33%), Methanoculleus (11% to 15%), and Methanosaeta (13% to 18%). The methane production rate was significantly correlated with bacterial communities (Pseudomonas, Clostridium, Altererythrobacter atlanticus), archaeal communities (Methanosarcina, Methanoculleus, Methanosaeta, and Methanoplanus), and biofilm characteristics (chemical oxygen demand (COD) and EPS). These findings showed that a carrier biofilm could efficiently increase methane production.

The growth and yield of Pleurotus florida mushroom were evaluated in media with corn husk and wood sawdust substrates. Five formulations of substrates, namely 0%, 25%, 50%, 75%, and 100% of wood sawdust substituted with corn husk, were tested with 0% corn husk or 100% wood sawdust serving as the control. The total number of fruiting bodies, the number of effective fruiting bodies, the total fresh weight and dry weight of the mushroom, and biological efficiency were significantly increased with as low as 25% corn husk in the substrate, and they showed a significant increasing trend as the composition of corn husk in the substrate increased. Superior yield was produced by P. florida cultivated in 100% corn husk, where the total number of fruiting bodies, the number of effective fruiting bodies, the total fresh weight, and the total dry weight of the mushroom were 4.8 times, 5.4 times, 4.6 times, and 5.4 times greater than the control, respectively. The biological efficiency of P. florida increased gradually from 8.8% in the control to 51.37% in the 100% corn husk substrate. Therefore, corn husk could be exploited as a substitute or alternative substrate to wood sawdust for more sustainable production of P. florida.

Sitting comfort is primarily determined by the cushioning capability of the seat foundation. Limited literature has been found related to the effects that different sized human buttocks had on the cushioning capability of the seat foundation. Moreover, there is no testing method specialized to measure the load-deformation behavior of foam cushions that imitates the sitting behavior between indenters with different sizes and seat support. This study investigated the effects of various indenter diameters (20 cm, 30 cm, 36 cm, 41 cm, 51 cm, and 58 cm), foam stiffness levels (high and low), and seat bases (spring versus solid flat panel) on the compressive load-deformation behavior of upholstered seat foundations. The load-deformation curves of all the tested foam-seat base combinations exhibited three typical regions, i.e., linear elasticity, plateau, and densification, when subjected to the loads applied through different indenter diameters. Statistical results indicated that the primary effects of the indenter diameter, foam stiffness level, and seat base had significant effects on the spring constants, which represented the slopes of lines in these three regions. In addition, a regression technique was proposed to derive power equations for the estimation of the spring constants of a seat foundation as a function of the indenter diameter, foam material stiffness, and seat base type.