Research Articles

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.

Elongation is an important property of many packaging board and paper grades. Paper with high extensibility could provide an alternative for oil-based packaging materials. Micro- (CMF) and nanofibrillated (CNF) cellulose are known to increase the strength of a paper, but their effect on the drying shrinkage and elongation is not well-studied. In this work, paper was reinforced with fibrillated material. Added fibrillated material increased the drying shrinkage, which was generally proportional to the increase of paper elongation before breakage. Results differed depending on the fibrillated material and how it was added to paper (wet-end addition or spray application). The papers were dried unrestrained in order to achieve the highest elongation potential for the paper. Spray application of CMF increased elongation by 13%, while wet-end additions increased elongation by 20% and also strength by 10%, but only with high dosages. Spray application of oxidized-CNF improved elongation by 33%, while wet-end applications increased only strength by 20%. Thus, boosting the drying shrinkage with fibrillated cellulose is one potential way to increase elongation and 3D formability of paper.

The interlaminar shear stresses of the three-layer, five-layer, and seven-layer cross laminated timber (CLT) and those of the oriented laminated beams were calculated according to Hooke’s law and the differential relationship between the beam bending moment and shear force. The interlaminar and maximum shear stresses of the CLT beam are related to the number of CLT layers and to the elastic modulus ratio E_L/E_T (or E_L/E_R) of the parallel and perpendicular layers. The interlaminar shear strength of the Hemlock CLT was positively correlated with the elastic modulus of its parallel layer. The results showed that the CLT short-span beams had three failure modes when subjected to a three-point bending test, namely perpendicular layer rolling shear failure, CLT interlaminar shear failure, and parallel layer bending failure. The shear stress of the oriented laminated beam followed a parabolic distribution along the height of the section, while the shear stress of the orthogonally laminated beams tended to be balanced, rather than parabolically distributed along the height of section. The short beam three-point bending method was able to effectively test the interlaminar shear strength of CLT due to its stable and readable load.

Formable papers can be used as an alternative to rigid plastics for making 3D shapes for packaging applications. However, commercial use of formable paper is currently limited, due to its poor extensibility. Cellulosic fibres can be combined with polyurethanes to improve the deformability of resulting fibre-polymer composites. This work describes the effect of spray and wet-end addition of polyurethane dispersions to paper to enhance the extensibility and formability of paper. The increase in extensibility was directly proportional to the amount of polyurethane retained in the paper. Absolute improvements in extensibility were as high as 4 to 6 percentage points. Improved extensibility resulted in better formability of paper, which eventually could allow it to compete with plastic packaging in certain applications.

A strategic method that utilizes the co-culture of Clostridium thermocellum ATCC 27405 and Thermoanaerobacterium thermosaccharolyticum DSM 571 was developed to improve the ethanol yield from the thermophilic fermentation of Salix. The co-culture conditions of the two strains were optimized using single factor and response surface experiments to enhance the ethanol yield. An even higher ethanol yield was obtained under the optimum co-culture conditions in fermenter tanks than what was observed in pre-experiments in serum bottles. The maximal ethanol concentration and yield were 0.2 g/L and 11.1%, respectively, and with a 26.4% cellulose degradation ratio and 13.8% hemicellulose degradation ratio when the pH was kept stable at 7.0 in fermenter tanks.