The thermal, thermo-mechanical and flammability properties of kenaf core hybrid polymer nanocomposites reinforced with unbleached and bleached nanocrystalline cellulose (NCC) were studied. The studied chemical composition found that unbleached NCC (NCC-UB) had 90% more lignin content compared to bleached NCC (NCC-B). Nanocelluloses were incorporated within polypropylene (PP) as the matrix, together with kenaf core as a main reinforcement and maleic anhydride grafted polypropylene (MAPP) as a coupling agent via a melt mixing compounding process. The result showed that the thermal stability of the nanocomposites was generally affected by the presence of lignin in NCC-UB and sulfate group on the surface of NCC-B. The residual lignin in NCC-UB appeared to overcome the poor thermal stability of the composites that was caused by sulfation during the hydrolysis process. The lignin helped to promote the late degradation of the nanocomposites, with the melting temperature occurring at a relatively higher temperature of 219.1 °C for PP/NCC-UB, compared to 185.9 °C for PP/NCC-B. Between the two types of nanocomposites, PP/NCC-B had notably lower thermo-mechanical properties, which can be attributed to the poor bonding and dispersion properties of the NCC-B in the nanocomposites blend. The PP/NCC-UB showed better thermal properties due to the effect of residual lignin, which acted as a compatibilizer between NCC-UB and polymer matrix, thus improved the bonding properties. The residual lignin in PP/NCC-UB helped to promote char formation and slowed down the burning process, thus increasing the flame resistance of the nanocomposites. Overall, the residual lignin on the surface of NCC-UB appeared to aid better stability on the thermal and flammability properties of the nanocomposites.

Bamboo requires treatment to extend its service life. However, as bamboo strips could serve as a suitable candidate for lamination, the treatment may affect its bendability. The current study investigated the effects of boric acid treatment on the physical, mechanical, adhesion, and morphological properties of bamboo strips. Owing to their availability and popularity in local industries, four Malaysian bamboo species were used in this study, namely Gigantochloa scortechinii, Gigantochloa levis, Dendrocalamus asper, and Bambusa vulgaris. These four species’ bamboo strips were treated with 5% boric acid and their properties were evaluated. The findings revealed that the boric acid treatment had varying degrees of effect on the properties of the bamboo. Despite having lower treatability and stability, both G. scortechinii and G. levis have greatly superior mechanical properties that justify their use in the production of laminated products. The boric acid treatment was found to provide several benefits to bamboo strips intended for lamination, including increased wettability, dimensional stability, and mechanical strength.

Eucalyptus hybrid has been planted rigorously in wet tropical regions including Malaysia. Recently, there was a report on the occurrence of stem canker on these trees. However, the extent of the infections by this stem canker is unknown. The aim of this study was to evaluate the influence of stem canker disease, Chrysoporthe deuterocubensis, on the physical and mechanical properties of 11-year-old E. urophylla × E. grandis or also known as E. urograndis. The samples were taken from infected and healthy trees that were segregated into different classes based on the severity of the attack, i.e., healthy (class 1), moderately infected (class 2), severely infected (class 3) and very severely infected (class 4). A total of 1440 samples from four infection classes were used in this study. The physical and mechanical properties were determined according to the standard test procedures specified by the International Organization for Standardization (ISO) 13061:2014 (Parts 1 to 4, 13, 14 and 17) and British Standard (BS 373: 1957). From the result, a significant effect by the infection classes was observed on physical and mechanical properties of E. urograndis. All infected wood experienced less shrinkage compared to that of a healthy one, particularly the volumetric (Vol_sh) and radial shrinkage (R_sh). Wood from class 2 and class 3 was less affected by the infection while the majority of wood from class 4 had significantly lower density and poorer strength. Based on the strength data, wood from infection class 2 can be considered to be used for non-structural applications such as furniture, interior finishing, window frames and doors since reduction in mechanical properties was observed. Wood from class 3 would need further investigation to examine its suitability for structural applications.

Eucalyptus pellita F. Muell. is currently the predominant tree species deployed for tree plantation establishment in some parts of Borneo, particularly Sabah state, Malaysia. Its low disease susceptibility, good growth and form, and desirable wood properties make E. pellita particularly suitable for plantation development in the wet tropical regions of south-east Asia. In spite the many positive traits, practical field observations indicate that the species is susceptible to end-splitting. There is some anecdotal evidence to suggest a genetic relationship with the incidence of end-split, although these observations were not statistically tested. This study evaluates the occurrence of end-splitting in five-year old plantation E. pellita in Sabah as affected by family and growth attributes. An existing progeny tree breeding trial, involving seeds that originated from Papua New Guinea, China, Vietnam, Australia, Sabah, and Sarawak with 106 families, was used to carry out the split assessment. Logs from the second thinning were cut into 2.2-m-long sections. The end splits were measured three days later; the incidence and severity of splitting were assessed at both the large and small ends of each log by using a designated split scoring system. The study shows that 99% of all log cross sections (per cut surface) experienced signs of splitting, with an average of 2.7 splits per cut surface. Overall, 54% of all splits were classed as ‘Three-Quarter Radial Splits’ while the occurrence of internal splits was negligible. Split severity showed a heritable and significant difference (h² = 0.24 at p ≤ 0.05) among the family levels. Splitting was also significantly related to growth factors such as tree height and diameter at breast height (DBH). The findings suggest that end-splitting is caused by family–environment interactions. This offers the opportunity to improve the wood resource of E. pellita via breeding strategies.

This study assessed the machining properties of 11-year-old Eucalyptus urophylla × E. grandis, known as E. urograndis wood, that was infected by stem canker disease, Chrysoporthe deuterocubensis. Instead of being discarded directly, the study aimed to explore the possibility of infected trees being used in other applications such as furniture. Sawing, planing, and boring properties as well as the surface roughness of the healthy and infected trees were evaluated. The samples were collected from infected and healthy trees and classified according to the severity of the attack: healthy (class 1), moderately infected (class 2), severely infected (class 3), and very severely infected (class 4). Prior to sawing, planing, and boring, the samples were prepared according to ASTM D 1666-11 Standard Test Methods for Conducting Machining Tests of Wood and Wood-Base Materials. All samples were sawn, planed, and bored and were evaluated for their respective machining quality. The surface roughness of the machined samples was also assessed. Overall, E. urograndis of different infection severity has very good machining properties ranging from Grade I to III. Fuzzy grain, chip grain, chip mark, and tear out are the most commonly seen physical defects. As for surface roughness, healthy trees have lower surface roughness compared to that of infected trees, which indicates a better surface quality. The findings of this study suggested that infected E. urograndis can still be used in many applications. The results of this study will provide us with better knowledge about the machining performance of disease-infected E. urograndis wood and its possibilities to be used as raw material for the wood products industry.

Bamboo is a lignocellulosic material characterized by its high hygroscopicity, which refers to the ability of material to absorb and retain moisture from the surrounding environment. This attribute could adversely affect its dimensional stability and resistance against deterioration agents. Thus, a study was conducted to investigate the effect of thermal modification on the hygroscopic, mechanical, and chemical properties of three-year-old Gigantochloa scortechinii, a native and highly exploited bamboo species in Malaysia. Overall, heat treatment effectively reduced the equilibrium moisture content and improved the dimensional stability of bamboo, with samples treated at 210 °C exhibited the most significant moisture resistance of up to 95.6% anti-swelling efficiency (ASE). The heat-treated bamboo exhibited an improvement in modulus of elasticity (MOE) at intermediate temperatures (170–190 °C) whereas modulus of rupture (MOR) declined at 210 °C. Chemical analysis indicated that a significant reduction in hemicellulose content and a relative increase in α-cellulose and lignin contributed to the improved moisture resistance of heat-treated bamboo. The results demonstrate the viability of heat treatment in producing quality thermally modified bamboo as an alternative raw material for construction materials and furniture manufacturing, thereby contributing to the development of Malaysia’s bamboo industry.