Research Articles

Kenaf is one of the important plants cultivated for natural fibres globally and is regarded as an industrial crop in Malaysia for various applications. This study was conducted to determine the effects of orientation on the tensile and flexural strengths, Charpy impact test, and morphological properties of kenaf fibre-reinforced poly vinyl butyral (PVB) composites. Laminates of 40% fibre weight fraction were manufactured using the hot press manufacturing technique at 0°/90° and 45°/−45° orientations, and eight specimens were prepared for each test. The mechanical properties of the composites were variably affected by the fibre orientation angle. The results showed that the composites at 0o/90o had the highest tensile strength, flexural strength, and flexural modulus, while the elongation at break was almost the same. Additionally, tests were carried out on the composites to determine their impact energy and impact strength. The results revealed that impact properties were affected in markedly different ways by different orientations. The composite at 45°/−45° offered better impact properties than the composites at 0°/90°. In addition, scanning electron microscopy for impact specimens was employed to demonstrate the different failures in the fracture surfaces.

A study was carried out to assess the dust emission and working conditions in the bamboo and rubberwood furniture manufacturing industries in Malaysia. The emission of wood dust arising from these industries was measured in each main work station in the mills. Meanwhile, a questionnaire-based survey was conducted among 5900 workers in 45 companies to obtain information on the occupational accidents that occurred in the mills. The data were collected, compiled, and analyzed using the SPSS package. The highest dust emission from the sanding operation resulted in respiratory ailments among workers. The occurrence of injuries particularly to the hand, wrist, fingers and forearm was due to the prevailing working conditions, safety climate and workers characteristics. The dust exposure levels and working conditions were much more severe in the bamboo furniture manufacturing industry. As a result, a review of existing of dust exposure levels in the woodworking industry is warranted.

Dendrocalamus brandisii is an edible bamboo species found in Southwest China and South Asia. However, there is limited information about the anatomical and chemical information of its culms for its utilization and processing. In this paper, the anatomical and chemical properties of different age culms were determined. There are three vascular bundle types found in its culms. The radial length-to-tangential diameter ratio of vascular bundles varied with culm zone but did not vary with age. The outer diameter of metaxylem vessels showed a similar trend. The fiber length (L), wall thickness (W), and Runkel ratio increased with age, while the fiber length-to-outer diameter ratio (L/D) and lumen diameter (Ld) decreased with age. The chemical properties of D. brandisii also differed with age class and height. The holocellulose and ash content decreased from age 1 to 2 years and then increased at year 3. The acid-insoluble lignin, alcohol-toluene extractives, and silica contents increased with age class, whereas the acid-soluble lignin exhibited the opposite trend. The fiber length and L/D values of D. brandisii suggest it would be suitable material for pulp fibers, but its lignin content was relatively high compared with other bamboo species.

Building materials can release a wide range of pollutants, particularly the volatile organic compounds (VOCs) and formaldehyde, which can cause indoor air related health problems. Bake-out technology is a cost-efficient method to reduce emissions of toxic substance from building materials in residential housing units. The temperature rise and the bake-out performance of MDF panels were evaluated in this work with three types of infrared radiation apparatus. Each MDF panel was radiated from three types of infrared radiation apparatus over 24 hours. The temperature was confirmed using data logging equipment according to elapsed time of infrared radiation. The formaldehyde emission was analyzed by desiccator method. In addition, thermal extractor (TE) analysis was used to determine the effect of NIR radiation on elapsed time. From the results it was determined that the NIR radiation method can be regarded as an effective way to transfer heat from material’s surface to the other side. Furthermore, the bake-out performance confirmed that the NIR radiation had a significant effect on reducing the formaldehyde concentration within a short period of radiation time.

This study investigated sulfite pretreatment to overcome recalcitrance of lignocelluloses (SPORL) pretreatment and subsequent enzymatic digestibility of undigested dairy manure to preliminarily assess its potential use as an inexpensive feedstock for cellulosic bioethanol production. The sulfite pretreatment was carried out in a factorial analysis using 163 to 197 °C for 3 to 37 min with 0.8% to 4.2% sulfuric acid combined with 2.6% to 9.4% sodium sulfite. These treatments were compared with other standard pretreatments of dilute acid, and hot and cold alkali pretreatments. This comparative study showed that the sulfite pretreatment, through its combined effects of hemicellulose and lignin removal and lignin sulfonation, is more effective than the diluted acid and alkali pretreatments to improve the enzymatic digestibility of dairy manure.

The aim of this investigation was to design and determine the mechanical properties of innovative, externally invisible, 3D-printed cabinet furniture joints that can be assembled without the use of tools. The cognitive objective of the study was to ascertain the stiffness and strength of designed joints that differed in the number and length of fasteners, as well as in the kind of connected panel materials. During the tests, a digital image analysis method was used for verifying analytical calculations. The finite element method was used for determining the mechanical properties of joints. Results showed that the joint designed with a dual-conical fastener was characterized by high stiffness and strength. The stiffness and strength of the joint depended on the number and length of fasteners. The low level of stress in the panel elements guaranteed durable, safe utilization of cabinet furniture made of medium density fiberboard and particleboard. In conclusion, ease of assembly and disassembly of joints without tools, external invisibility, good aesthetics, high resistance, and stiffness ensure a high potential for 3D-printed cabinet furniture joints in industry and trade.

The objective of this work was to study the biodegradability of polylactic acid (PLA)/paddy straw powder (PSP) biocomposites. Environmental degradation was evaluated by composting the biocomposite samples into the soil. Different techniques, including mechanical tests and scanning electron microscopy (SEM), were used to obtain a view of the degradation that occurred during the soil burial of the biocomposites. Results of the mechanical tests showed that an increasing content of PSP in the biocomposites decreased the tensile strength and elongation at break (EB), while it increased the modulus of elasticity after six months of exposure. Scanning electron microscopy on the surface after soil burial showed that the filler was poorly wetted by the matrix. This explains the reduction in tensile strength and the elongation at break after soil burial. Differential scanning calorimetry results indicated that the crystallinity of the biocomposites increased with longer composting periods.

Lemon grass is an inexpensive raw material that can be used to produce natural silica. A method using hydrochloric acid (HCl) leaching followed by thermal combustion at 600 °C was developed to produce purified silica from lemon grass. Acid leaching temperatures of 33, 50, 80, and 110 °C were used. The silica content of the lemon grass ash was characterized using X-ray fluorescence (XRF), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) analysis. The shape and texture of the lemon grass ash were studied using SEM. The highest silica content (98.59%) was produced by lemon grass that had been treated at the highest leaching temperature (110 °C). Other elements that were found in the lemon grass ash were magnesium, calcium, potassium, and chlorine. XRD analysis showed that the crystallinity of the silica in treated lemon grass ash increased with increasing leaching temperature. The FTIR analysis confirmed the presence of siloxane and silanol bonds in lemon grass that was calcined at different leaching temperatures.

The effects of thermal-alkaline pretreatment on dewatered activated sludge (DAS) solubilisation and subsequent high-solid anaerobic digestion were studied by response surface methodology (RSM) from 105 to 135 °C and between 5 and 35 mg alkaline/g total solid (TS) DAS. Soluble chemical oxygen demand (SCOD), soluble carbohydrates, and protein concentrations were significantly enhanced in thermal-alkaline pretreated DAS samples. Daily methane yield increased at the middle of digestion, and cumulative methane yield (CMY) significantly increased after thermal-alkaline pretreatment. A first-order linear model of temperature and alkaline was significant for SCOD by RSM, and the determination coefficient (R2) was 94.62%. The quadratic model of temperature and alkaline was also significant for methane yield. R2 of 99.80% confirmed that the model used in this study fit the experimental variables very well. Using the model, the optimum pretreatment condition of methane yield was obtained at 134.95 °C and 23.77 mg alkali. Therefore, RSM was an effective tool in predicting the DAS pretreatment condition for optimum methane yield.

In this paper, milled corncob powder was treated with sodium chlorite to remove lignin, and the resulting holocellulose was optionally modified with cationic agent. The derivative product was investigated using elemental analysis, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The influences of the dosage of the cationic agent, reaction temperature, particle size, dosage of paper strengthening agent, and pH value of the pulp on the paper physical properties were studied. The results indicated that cationic corncob holocellulose can improve the tensile index, burst index, and folding endurance of paper. When the dosage of cationic agent was 25% and the reaction temperature was set to 70 °C, the resulting tensile index, burst index, and folding endurance increased by 7.15%, 13.74%, and 55.95%, respectively, when compared with the control paper. The particle size of the raw material and the dosage of strengthening agent also greatly influenced the paper’s properties. The SEM analysis showed that the combination of fibers improved the strength properties of the paper after adding the strengthening agent. These results provide a method for value-added use of corncob waste.