Volume 13 Issue 3

Withdrawal strengths of commercially available hardwood dowels were examined in this work. Multi-grooved dowels with a straight surface pattern and with pre-glued polyvinyl acetate (PVAc) were tested. Additionally, standard dowels with different single- and multi-grooved surface patterns were also tested, which were not pre-glued. Standard dowels were bonded with two types of PVAc and one type of polyurethane (PUR) adhesive. The influence of the type of dowel, the surface pattern, the dowel diameter, and the type of adhesive used on the dowel joint strength were investigated. Lower average strengths were observed for single-grooved dowels with a spiral pattern (4.9 MPa); failures generally occurred at the first or second thread of the spiral groove. For the pre-glued dowels, there were differences in the observed strengths, which depended upon how the PVAc adhesive was activated. Lower withdrawal strengths were noted for the pre-glued dowels when they were activated by dipping them in water (3.0 MPa) versus adding water directly to the pre-drilled holes (4.7 MPa to 5.4 MPa).

An attempt to correlate biomass characteristics to its susceptibility to enzymes is often inconclusive via investigation of the variables of hydrothermal pretreatment. Based on an integrated analysis of physicochemical properties, cellulose bioconversion, loss of pentose sugars, formation of inhibitory products, and the cost of energy, the optimal hydrothermal operation for wheat straw (1:20 w/v%) was found. This optimal operation involved cooling the hydrolysates as soon as the temperature reached 180 °C. Finally, a total of 40.7% glucose and 70.3% sugars were recovered during subsequent enzymatic hydrolysis. Although treatment at a noticeably increased severity with a long incubation time could lead to almost 100% conversion of cellulose, the weight losses (mainly sugars) and inhibitors in the process liquid were not well suited for an industrial scale operation.

High specific surface area activated carbon was prepared by improving the process conditions of phosphoric acid activation and hulless barley straw and plain wheat straw as raw materials. The effects of the activation time on the pore structure and specific surface area of two types of activated carbon were investigated. The results revealed that soaking straws in the high concentrations of H3PO4 for 0.5 h to ensure complete soaking and then removing the straws from H3PO4 solution to activate was beneficial to the infiltration of H3PO4 in the raw material, and there was an increase in the surface area of activated carbon. The largest specific surface area of activated carbon prepared from plain wheat straw and hulless barley straw was 1524 m2/g and 1885 m2/g, respectively. Thermogravimetric analysis and scanning electron microscopy showed that the higher cellulose content, higher hemicellulose content, and smaller fiber morphology in hulless barley straw compared with wheat straw were the main reasons for the more abundant pore structure and higher specific surface area of the activated carbon.

A cellulase-free, degumming crude enzyme was produced by Bacillus cereus HDYM-02, using konjaku flour as an inexpensive substrate. After 48 h fermentation, this crude enzyme consisted of pectinase and mannanase, whose maximum activity was 756.7 U/mL and 2967.3 U/mL, respectively. This crude enzyme exhibited considerable stability under the conditions resembling industrial flax retting. After 120 h incubation, more than 50% of the maximum activity of both pectinase and mannanase was retained at pH value 4.0 to 7.0, and at least 70% of the maximum activity was detected at 25 °C to 40 °C. The degumming liquid retted by this crude enzyme contained more galacturonic acid and reducing sugar than those in the degumming liquid retted by commercial pectinase. The application of B. cereus HDYM-02 crude enzyme resulted in higher weight loss of flax stems, better properties, higher productivities, and smoother surfaces of flax fibres. This study showed promise for the use of B. cereus HDYM-02 crude enzyme for flax retting in the textile industry.

The dilute acid-catalyzed extraction of hemicellulosic monosaccharides from the short-rotation coppice Salix schwerinii E. Wolf was optimized to find a balance between the yields of fermentable monosaccharides and sugar degradation products for non-detoxified acetone-butanol-ethanol fermentation with Clostridium acetobutylicum. At the same time, the cellulosic and lignin fractions were kept as intact as possible for further refining. The highest xylose and glucose yields in the liquid prehydrolysate were 65% and 9.45% of their respective original content at a combined severity of 2.29. Increased concentrations of glucose and sugar degradation products in the liquid prehydrolysates were detected with an increasing pretreatment temperature and combined severity, while the acid-insoluble lignin remained stable. During the fermentation of the non-detoxified liquid prehydrolysate with grain starch as the supplement, 66% of the xylose was utilized, and the butanol and acetone-butanol-ethanol yields were 0.22 g/g and 0.35 g/g monosaccharides, respectively, in the fermentation medium. The results suggested that the hemicellulose in S. schwerinii can be separately extracted as a side stream and utilized for butanol fermentation with starch-based materials without a separate detoxification stage.

The lower tolerance limits (LTLs) for two-pin moment-resisting dowel joints, constructed of red oak and white oak, were estimated. Dowel joints are widely used in furniture manufacturing, especially for tables and chairs. Despite numerous studies to determine the strength capacities of dowel joints, their design values have not been established. For this purpose, T-shaped edgewise dowel joints were constructed to determine their ultimate failure load capacity levels.  In tolerance analysis, the k-tolerance factor changes depending on sample sizes and confidence/proportion levels. Therefore, sample sizes were determined using a modified Faulkenberry-Week method for a univariate normally distributed data set created for a pilot study, which had 30 specimens. At least 215 specimens were required to make tolerance analyses at the 99/99 confidence/proportion level. Accordingly, 220 specimens were constructed. The LTL values were obtained at the 75/75, 90/75, 75/90, 90/90, 95/90, 90/95, 95/95, 99/95, 95/99, and 99/99 confidence/proportion levels to estimate reasonable design values. The results of the study indicated that the LTL method provides a sound design value estimate for dowel joints used in furniture frames.

The Malaysian furniture industry is the country’s fastest growing sub-sector within the wood-based industry, and its socio-economic importance cannot be taken lightly. The industry is driven primarily by comparative advantages derived from low cost factor inputs, which has eroded in recent years due to escalating production cost. Further, the increasing competition from other cheaper producing nations, particularly China and Vietnam, is also putting a damper on the future competitiveness of the industry in Malaysia. To remain competitive, the Malaysian furniture industry must transform and advance the value-chain through innovation and value-addition. Although the government has played a pivotal role in providing a broad policy framework to support value-adding and innovative activities, success has been limited. This study evaluated the extent of innovation and its sources in the Malaysian furniture industry through an internet-based survey. The results indicated that external sources of innovation were more important than internal sources. The factor analysis showed that external inputs, market demand, and in-house research and development were the most important drivers of the innovation in the Malaysian furniture industry. Therefore, the furniture industry in Malaysia will require policy support to enhance its inherent capability for innovation in the long-term.

Due to its different organizational structures, dense hard husk, and loose soft core, corn stover (CS) is more resistant to transformation into monosaccharides for biofuel production in comparison to rice straw or wheat straw. In this paper, before pretreatment with sulfur trioxide micro-thermal explosion and dilute alkali (STEX-DA), CS was cut into 2 cm to 3 cm lengths in the transverse direction and cross opening in the vertical direction. During the process of STEX-DA, the structures of cores of corn stover (CS-C) and husks of corn stover (CS-H) were separately studied via scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) analysis. Furthermore, the components content and reducing sugars yield were calculated. The results showed that the CS-C achieved 66.7% of lignin removal rate, and the reducing sugars yield (calculated by original dry weight of straw) was 70.8%, while the CS-H displayed values of 64.7% and 55.3%, respectively. This result indicated that STEX-DA pretreatment could facilitate corn stover usage as a renewable energy source.

The objective of this study was to determine the preferences of architects for wood and wood products for specific applications and to assess the attributes that influenced its utilization in the construction sector in Peninsular Malaysia. A questionnaire survey was conducted among 500 practicing architects throughout Peninsular Malaysia, with a response of 27%. The application of wood and wood products by architects was focused primarily on non-structural applications rather than structural applications. It was found that cost, customer demand, durability, natural beauty, availability, ease of design, and workability were primary considerations for architects in specifying wood and wood products in building construction. A factor analysis of the results showed that building regulations, material quality and beauty, customer demand, and design and assembly were the primary determinants that influence architects specifying and using wood and wood products in building construction. It was apparent that the use of wood and wood products in building construction in Peninsular Malaysia has the potential to be further increased through advertising and marketing in the material among the general public, as well as architects and specifiers.

Cationic polyacrylamides (C-PAMs) have been widely used as flocculating agents to aggregate particles carrying negatively charged surfaces. This study examined the effects of hydrolysis of C-PAM on its adsorption behaviour and flocculation of negatively charged particles, specifically ground calcium carbonate (GCC). C-PAM hydrolysis was examined using polyelectrolyte titration and ion chromatography, while the adsorption behaviour of the polymer was monitored using a quartz crystal microbalance with dissipation (QCM-D). Laser diffraction spectroscopy was used to measure the size of the GCC aggregates under neutral and alkaline conditions. The charge density measurements and ion chromatograms indicated that the hydrolysis of C-PAM was accelerated with increased pH and temperature. The QCM-D measurements of hydrolysed C-PAMs, adsorbed on a substrate with a flat and rigid structure, indicated that hydrolysis of C-PAM suppressed its ability to cause inter-particle bridging flocculation, which reduced the aggregate size of GCC.