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The objective of this work was to study the influence of cellulose nanofibrils (CNF) on the physical, mechanical, and thermal properties of Jatropha oil-based waterborne polyurethane (WBPU) nanocomposite films. The polyol to produce polyurethane was synthesized from crude Jatropha oil through epoxidation and ring-opening method. The chain extender, 1,6-hexanediol, was used to improve film elasticity by 0.1, 0.25, and 0.5 wt.% of CNF loading was incorporated to enhance film performance. Mechanical performance was studied using a universal test machine as specified in ASTM D638-03 Type V and was achieved by 0.18 MPa at 0.5 wt.% of CNF. Thermal gravimetric analysis (TGA) was performed to measure the temperature of degradation and the chemical crosslinking and film morphology were studied using Fourier-transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). The results showed that when the CNF was incorporated, it was found to enhance the nanocomposite film, in particular its mechanical and thermal properties supported by morphology. Nanocomposite film with 0.5 wt.% of CNF showed the highest improvement in terms of tensile strength, Young’s modulus, and thermal degradation. Although the contact angle decreases as the CNF content increases, the effect on the water absorption of the film was found to be relatively small (<3.5%). The difference between the neat WPBU and the highest CNF loading film was not more than 1%, even after 5 days of being immersed in water.

Citric acid (CA) can be found naturally in fruits and vegetables, particularly citrus fruit. CA is widely used in many fields but its usage as a green modifying agent and binder for wood is barely addressed. Esterification is one of the most common chemical reactions applied in wood modification. CA contains three carboxyl groups, making it possible to attain at least two esterification reactions that are required for crosslinking when reacting with the hydroxyl groups of the cell wall polymers. In addition, the reaction could form ester linkages to bring adhesivity and good bonding characteristics, and therefore CA could be used as wood binder too. This paper presents a review concerning the usage of CA as a wood modifying agent and binder. For wood modification, the reaction mechanism between wood and CA and the pros and cons of using CA are discussed. CA and its combination with various reactants and their respective optimum parameters are also compiled in this paper. As for the major wood bonding component, the bonding mechanism and types of wood composites bonded with CA are presented. The best working conditions for the CA in the fabrication of wood-based panels are discussed. In addition, the environmental impacts and future outlook of CA-treated wood and bonded composite are also considered.

Particleboard was produced by mixing oil heat-treated rubberwood particles at different ratios, with the goal of achieving high dimensional stability. Rubberwood particles were soaked in palm oil for 2 h and heat treated at 200 °C for 2 h. The treated particles were soaked in boiling water for 30 min to remove oil and were tested for chemical alteration and thermal characterization via Fourier-transform infrared spectroscopy and thermogravimetric analysis. Particleboard was fabricated by mixing treated rubberwood particles (30%, 50%, and 70%) with untreated particles (70%, 50%, and 30%, respective to previous percentages) and bonded with urea-formaldehyde (UF) resin. The results revealed that oil-heat treated particles had greater thermal stability than the untreated particles. The addition of oil heat treated particles improved the physical properties of the particleboard with no significant reduction in mechanical strength. However, this was only valid for ratios of 70% untreated to 30% treated and 50% untreated to 50% treated. When a ratio of 70% oil heat treated particles was used, both the physical and mechanical properties were reduced drastically, due to bonding interference caused by excessive oil content. Particleboard made with a ratio of 5:5 (treated to untreated) exhibited the best physical and mechanical properties.

Wood or natural-based products will continue to be susceptible to degradation. However, this degradation process can be slow-down by introducing additives or certain treatment. The properties (i.e. mechanical, physical, bonding etc.) of wood-based panel such as Medium Density Fiberboard (MDF) and Particleboard (PB) degrades in function with period of usage or exposure due to factors in surrounding conditions. This work focuses on the study of mechanical performance deterioration for MDF and PB after condition in the air-conditioned room and ambient for three months. Through this study, comparisons of various board variables (board types, exposure conditions, board thicknesses, resin types) influences the board performance degradation process. The project also studied the effects of cold-water immersion (12, 24 and 72 hours) to the mechanical properties of the board. The mechanical performance of boards was evaluated based on static bending (Modulus of Elasticity and Modulus of Rupture) and internal bonding tests after exposed for 3 months. All boards (MDF and PB) used in this study were obtained from local commercial panel manufacturer and test according to JIS A 5908-1994. The findings show that all the variables studied: exposure conditions, resin type, board thickness and board type respectively, have a significant effect on the diminished strength of panel strengths. The conditioning method and board type found to influence foremost compared with resin type. Exposing both of panels in air-conditioned room found to delay the degradation compared with ambient exposure for tested properties; MOE, MOR and IB respectively. The board thickness seems influenced the degradation of the board in any exposure conditions; air conditioned, ambient or cold-water soaking. The thicker of the board, the greater the degradation occurred.

Semantan bamboo (Gigantochloa Scortechinii) was hydrothermally treated in three different buffered media, namely alkaline, neutral and acidic medium. Response surface methodology (RSM) models were developed for the influences of treatment temperature, treatment duration and pH of buffered media on dimensional stability of Semantan bamboo. The models suggested that treatment temperature is the most crucial factor that led to improvement in dimensional stability. Lengthened treatment time also exerted noticeable influence when the temperature remained constant. More dimensionally stable samples were obtained in neutral and alkaline media.

This study presented the effect of different fibre length and seawater treatment on mechanical properties of the fabricated composites. The composite was reinforced with fixed 30wt.% of fibre loading. Sugar palm was treated using sea water for 30 days and have been cut into three different lengths by 5cm, 10cm and 15cm. The mechanical properties of the untreated and treated fibre with different fibre length composites were characterised includes tensile test and flexural test. Treated sugar palm fibre composites with 15cm fibre length exhibited higher tensile strength at 18.33 MPa. However, it shows the lowest value for the tensile modulus at 4251.96MPa. The flexural strength shows an increasing trend as the fibre length increased up to 15cm and the maximum flexural strength was exhibited by treated sugar palm fibre with 5 cm at 80.80MPa.

With drastic depleting rubberwood supply, the Lembaga Getah Malaysia (LGM) has identified new clones of rubber trees that are expected to produce not solely latex but also timber. Among these clones, several clones from RRIM 2000 series were found to be fast growing with high yield of latex, high growth vigor, good growth form and are very suitable for timber production, particularly for the biocomposite industries. In this study, particleboards were manufactured from rubber tree clones of RRIM 2002, RRIM 2020 and RRIM 2025 which are also categorized as Latex Timber Clone (LTC). The properties of these particleboards were compared with those made from the currently planted tree clone ; PB 260. All clones from RRIM 2000 series were planted at 1000-1100 trees planting density and harvested for this study at 4 year-old. The resin used was E1-grade urea formaldehyde (UF) and the target density of the particleboard was 700 kgm-3. The basic and adhesion properties of these woods were evaluated and discussed in relation to the board performance i.e. physical and mechanical properties, and dimensional stability. These properties were determined according to Japanese Industrial Standard for Particleboard (JIS A 5908-2003). Among the clones studied, RRIM 2002 showed the best overall wood basic properties and board performance, which are comparable to or better than those of matured clone PB 260. The 25-year old PB 260 gives the highest specific gravity (0.601), lowest moisture content (70%), longer fibre length (1.3 mm) and thickest fibre wall thickness (6.2 μm). Clone RRIM 2002 gives comparable wood basic properties except for specific gravity (0.570), higher wood moisture content (94%) relatively longer fibre length (1.4 mm) and thicker fibre wall (5.5 μm). Except for specific gravity, the other two clones give poorer overall wood properties particularly the RRIM 2025. Both clones, however, produced relatively high specific gravity, 0.589 and 0.582 for RRIM 2020 and RRIM 20