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The common practice of using toxic chemicals as a preservative for rubberwood is much of a concern regarding environmental issues, its effect on human health, and compromising the wood's strength. This study focuses on the alternative strategy to preserve rubberwood using sodium acetate and sodium butyrate. These two salts were obtained from the reaction between sodium hydroxide and the fermentation products of landfill leachate, namely acetic acid and butyric acid. The effect of these salt concentrations and treatment duration on the rubberwood were studied and assessed from the biological decay, mechanical and chemical aspects. Almost all treated rubberwood subjected to decay by Phanerochaete chrysosporium, Trametes menziesii, species fungi A (white-rot), and species fungi B (brown-rot) have lower mass loss than untreated rubberwood. Treatment with 0.5M sodium butyrate was the best concentration in protecting the wood from degradation caused by fungal attacks. For the mechanical test, most of the salt concentrations positively impacted the bending strength and modulus of the treated rubberwood. Lastly, a chemical test conducted on rubberwood treated with 0.75M sodium butyrate for 21 days gave the highest retention and penetration of the salt into the rubberwood. [ABSTRACT FROM AUTHOR]

AbstractUtilizing furfurylated veneers to improve the quality of plywood has not been extensively studied before. This study investigated the characteristics of plywood made from furfurylated rubberwood (Hevea brasiliensis) veneers at various modification levels. Rubberwood veneers were first impregnated with furfuryl alcohol (FA) at different concentrations (40%, 70%, and 100%) with 3% citric acid as a catalyst for FA polymerization at 103 °C. The weight percent gain (WPG), dynamic mechanical analysis (DMA), and functional groups of the furfurylated veneers were analyzed. The furfurylated veneers were then used to form three layers of plywood using either polyurethane (PU) or epoxy resin as the adhesive. Various physical, mechanical, and morphological properties of the furfurylated plywood were characterized. The WPG of the veneers impregnated with 40%, 70%, and 100% FA were on average 32.2%, 54.1%, and 67.9%, respectively. DMA and ATR-FTIR analyses revealed differences between the control veneers and the furfurylated veneers. Furfurylation slightly decreased the bonding strength of PU-bonded plywood at 100% FA, while the epoxy-bonded plywood remained unchanged at all FA concentrations. Furfurylation reduced the delamination values of plywood, particularly for treatments with 40% and 100% FA. Moreover, the use of 100% FA reduced the thickness swelling, water absorption, and leaching values of the plywood after seven days of water immersion by 43.6%, 73.9%, and 73.8% with PU adhesive, and by 85.7%, 69.6%, and 80.2% with epoxy adhesive, respectively. The formation of furfurylated plywood in this study opens potential opportunities for using low-quality veneers from fast-growing wood species as substitutes for high-quality veneers from natural forests. [ABSTRACT FROM AUTHOR]

This study aimed to develop new composites and evaluate the physico-mechanical properties and formaldehyde content of flat-pressed three-layer particleboard (FPTP) made of bamboo (as a face material) and rubberwood (as a core material) residue bonded with urea-formaldehyde adhesive. Different ratios of core and face material were adopted to investigate the effects of these ratios on the properties of the particleboards. The results indicate that increasing the proportion of rubberwood particles enhanced mechanical properties. All particleboards complied with the maximum permissible thickness swelling percentage (12%) specified in IS 3087 (2005) for Grade 2 category boards. While the moduli of rupture and elasticity values increased with higher rubberwood content, the particleboards did not satisfy the IS 3087 (2005) standard overall. However, the internal bonding strength of T4 (0.5 N/mm²) met the minimum requirement. Nail and screw withdrawal resistance of the particleboards indicated significantly higher resistance with increased rubberwood proportion. Only T4 particleboards met the minimum requirement stipulated by IS 3087 (2005) regarding screw withdrawal resistance for both Grade 1 and Grade 2 category boards. All boards met the criteria for the E2 classification (formaldehyde content ≤ 30 mg/100 g for oven-dried boards). [ABSTRACT FROM AUTHOR]

This study empirically evaluated the performance of a downdraft biomass gasifier integrated with a diesel engine using a combination of biomass and diesel fuel. The employed downdraft gasifier consisted of two interconnected oil drums measuring 60x151 cm. A combustion chamber was installed in the conical steel drum with a central axis having a throat diameter of 31 cm. Rubberwood, tamarind wood, and sawdust were used as fuel sources. These woods were combusted to produce gas, which was subsequently channeled through a filtering and temperature-reduction apparatus before being blended with diesel fuel. A Nissan RD28 94 hp diesel engine was used for the experiments, with an airflow rate set at 0.226 m³/s. The experimental results showed that burning a mixture of rubberwood and sawdust (7.5 kg each) produced gas for 61 minutes. Tamarind wood combustion (15 kg) resulted in 58 minutes of gas production. Burning pure rubberwood (15 kg) produced gas for 37 minutes. Combusting a blend of tamarind wood and sawdust (7.5 kg each) produced gas for 45 minutes. The gooseberry wood (15 kg) was burned for 57 minutes with gas formation lasting 48 minutes. Adjusting the air input to the gasifier combustion chamber to 100%, the rubberwood and sawdust mixture exhibited the highest gas production. Furthermore, engaging the RD28 engine at 978 RPM in gear L resulted in the gear halting at 99 RPM after gradually adding steel blocks. The torque required to cease the gear was measured at 10.68 N.m, highlighting the potential for stopping gear L within the low-speed range due to misalignment between the engine's end flywheel and the gear pulley spline. [ABSTRACT FROM AUTHOR]

This study aimed to develop new composites and evaluate the physico-mechanical properties and formaldehyde content of flat-pressed three-layer particleboard (FPTP) made of bamboo (as a face material) and rubberwood (as a core material) residue bonded with urea-formaldehyde adhesive. Different ratios of core and face material were adopted to investigate the effects of these ratios on the properties of the particleboards. The results indicate that increasing the proportion of rubberwood particles enhanced mechanical properties. All particleboards complied with the maximum permissible thickness swelling percentage (12%) specified in IS 3087 (2005) for Grade 2 category boards. While the moduli of rupture and elasticity values increased with higher rubberwood content, the particleboards did not satisfy the IS 3087 (2005) standard overall. However, the internal bonding strength of T4 (0.5 N/mm2) met the minimum requirement. Nail and screw withdrawal resistance of the particleboards indicated significantly higher resistance with increased rubberwood proportion. Only T4 particleboards met the minimum requirement stipulated by IS 3087 (2005) regarding screw withdrawal resistance for both Grade 1 and Grade 2 category boards. All boards met the criteria for the E2 classification (formaldehyde content ≤ 30 mg/100 g for oven-dried boards).

The corrosion resistance of modification rubberwood with micro sized copper zinc compounds (MCZ) can reach the national level I corrosion resistance standard, but in order to adapt to complex environmental applications, the leaching resistance and dimensional stability need to be further improved. Propylene glycol was used to modify MCZ, and then combined with tannin-boric acid for synergistic treatment of rubberwood. The results showed that when the rubberwood was impregnated with PG-MCZ and modified with tannin-boric acid with a mass concentration of 1%, the leaching resistance of the treated wood was the best. At this point, the modified rubberwood had the best anti moisture expansion and anti drying shrinkage effects, and the best dimensional stability. Although the addition of propylene glycol slightly weakened the corrosion resistance of rubberwood, it can still meet the national level I corrosion resistance standard and improve flame retardancy and smoke suppression of rubberwood. This study has a positive effect on promoting the development and utilization of environmentally friendly wood preservatives. [ABSTRACT FROM AUTHOR]

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Heat treatment is an environmentally friendly method used to improve properties of rubberwood. In this work, the changes in the chemical composition, thermal behavior and thermal degradation kinetics of heat-treated Hevea brasiliensis (rubber tree) were evaluated using thermogravimetry, differential scanning calorimetry, and Fourier transform infrared spectroscopy. The rubberwood samples were exposed to temperatures of 180 °C and 220 °C in air under atmospheric pressure for durations of 15 25 and 35 h. Thermal analysis revealed degradation of hemicelluloses, an increase in the relative proportions of cellulose and lignin in heat-treated rubberwood. The thermal decomposition of rubberwood heat-treated at 220 °C started at a higher temperature compared to untreated wood. A shift in the position of peaks on differential thermogravimetry and differential scanning calorimetry curves of heat-treated samples was observed, indicating changes in the structure of wood polymers. The temperature of heat treatment had a stronger effect on the chemical composition of rubberwood than duration. Significant changes in the chemical composition of rubberwood occurred after the treatment duration of 15 h at both 180 °C and 220 °C. The duration of 25 h and 35 h had no further substantial effect. The isoconversional method of Flynn-Wall-Ozawa was used to determine the kinetics of thermal degradation of untreated and heat-treated rubberwood. It is found that the average values of activation energy in the conversion degree range of 0,05 - 0,65 (the thermal degradation of polysaccharides) increased with increasing treatment temperature and duration. Fourier transform infrared spectra demonstrated alterations in wood polymers.

Hevea brasiliensis (rubber tree), a major source of natural rubber, could also be an important source of lumber as senescence occurs. However, latex collection is known to affect Hevea brasiliensis (rubber tree) wood formation and consequently, wood properties. The impact tapping (cutting made in the bark of the tree for latex harvest) has on the tree and the way the tree responds after tapping is often overlooked. Knowledge on wood properties of tapped rubber trees in Nigeria would enhance its sustainable utilization which is especially important in developing countries where lumber is limited. Variation in specific gravity and shrinkage of rubberwood wood due to tapping duration was examined. Tapping duration had significant effect in specific gravity and longitudinal shrinkage of rubberwood but had no effect on tangential and radial shrinkage. The specific gravity (SG) of rubberwood ranged from 0,55 - 0,59. Longitudinal shrinkage (average 1,42 %) was higher than typically observed for mature wood. Average tangential shrinkage for rubberwood of all the ages was 5,37 % while radial shrinkage ranged from 2,87 % to 3,84 %. decrease in SG observed in trees tapped for 20 years may indicate the initiation of senescence. Tapped rubberwood could be used in areas not exposed to high moisture as well as in other wood composites.

The objective of this work was to investigate the effect and optimization of turning parameters such as spindle speed, feed rate, and depth of cut as well as wood sawdust content on the roughness quality of wood-plastic composites (WPCs). The Box–Behnken design and response surface methodology were used in experiments. Three roughness parameters, namely average roughness (Ra), root mean square average of roughness (Rq), and average maximum height (Rz) were employed to evaluate the surface quality of WPC samples. Based on the findings of the experiments, the Ra, Rq, and Rz values reduced with increasing spindle speed in a range of 430 to 1030 rpm, whereas the values increased when increasing the feed rate in a range of 0.05 to 0.15 mm/min. Also, an increase in depth of cut ranging from 1 to 3 mm and WPCs with a higher amount of wood sawdust in a range of 30 to 50 wt% raised their surface roughness. Finally, optimal conditions for the turning of the WPCs were determined to comprise a spindle speed of 781 rpm, a feed rate of 0.05 mm/min, a depth of cut of 2.8 mm, and wood sawdust content of 30 wt% with the highest desirability score of 1.000. Under such conditions, the sample had Ra, Rq, and Rz values of 1.8, 2.2, and 11.3 µm, respectively. The optimal conditions for turning can be used to effectively process different WPC products into various shapes.

Hevea brasiliensis (rubber tree), a major source of natural rubber, could also be an important source of lumber as senescence occurs. However, latex collection is known to affect Hevea brasiliensis (rubber tree) wood formation and consequently, wood properties. The impact tapping (cutting made in the bark of the tree for latex harvest) has on the tree and the way the tree responds after tapping is often overlooked. Knowledge on wood properties of tapped rubber trees in Nigeria would enhance its sustainable utilization which is especially important in developing countries where lumber is limited. Variation in specific gravity and shrinkage of rubberwood wood due to tapping duration was examined. Tapping duration had significant effect in specific gravity and longitudinal shrinkage of rubberwood but had no effect on tangential and radial shrinkage. The specific gravity (SG) of rubberwood ranged from 0,55 - 0,59. Longitudinal shrinkage (average 1,42 %) was higher than typically observed for mature wood. Average tangential shrinkage for rubberwood of all the ages was 5,37 % while radial shrinkage ranged from 2,87 % to 3,84 %. decrease in SG observed in trees tapped for 20 years may indicate the initiation of senescence. Tapped rubberwood could be used in areas not exposed to high moisture as well as in other wood composites. [ABSTRACT FROM AUTHOR]

The generation of internal stress (IS) in flat-sawn and quarter-sawn rubberwood boards during drying has been investigated using an online restoring force (RF) technique, which restrained a half-split rectangular wood specimen. Particular attention was given to the longest IS reversal regime. The IS development proceeds faster in the flat-sawn specimens than that in the quarter-sawn specimens while the maximum IS magnitudes in both specimens are rather similar. By normalizing the IS reversal period, a master IS profile, the derivative of the measured RF to the IS reversal time ratio versus the IS reversal time ratio, is proposed. This master curve, exhibiting some degree of independence from wood orientation and drying temperature, shows variations correlated with the free water content in the wet zone and the dry/wet zone fractions. The process of IS reversal, unaffected by temporary unrestraint, advances as the dry zone expands inwards and ends when the wet zone disappears. Assuming mechanical equilibrium between the dry and wet zones, the IS in both zones can be estimated from the RF data. The maximum tensile IS in the dry zone, indicating a risk of surface checks, evolves at slightly lower magnitudes at higher drying temperatures and is lower in the quarter-sawn specimens. The IS relaxation in the dry zone, still largely taking place in the absence of the applied RF, highlights the main contribution of the dry/wet zone fractions, continuing to proceed without restraining, to the IS development. These findings, emphasizing the significance of dry and wet zones, should pave the way for a better understanding of the IS development within wood during drying. [ABSTRACT FROM AUTHOR]

Abstract The objective of the study is to evaluate the properties of the plywood made from rubberwood veneers thermally treated at various temperatures. Rotary-peeled rubberwood veneers were thermally treated at 160, 170, 180, and 190 °C under 1 bar pressure. 5-ply plywood panels were produced using melamine urea formaldehyde (MUF) resin as binder. Dimensional stability, i.e., water absorption (WA) and thickness swelling (TS) as well as mechanical properties of the plywood were assessed. The results demonstrated that the dimensional stability of the plywood made from thermally treated rubberwood veneers improved as indicated by lower WA and TS values. The reduction in WA and TS values increased along with treatment temperatures. Darkening in the plywood as a result of heat treatment was observed. Meanwhile, heat treatment at 170 °C and 180 °C resulted in plywood with the highest modulus of rupture (MOR), modulus of elasticity (MOE) and shear strength. However, beyond that temperature, the mechanical strength of the plywood started to decline. Based on the findings in this work it appears that heat treatment of rubberwood veneers at temperatures ranging from 160 to 180 °C could have a potential to improve overall properties of plywood panels.

Rubberwood (Hevea brasiliensis Muell. Arg) is underutilized in most developing countries but has potential to be a solution to the shortage of wood for pulp, paper and wood composite products at the end of its production cycle. Determining and understanding its fibre properties (fibre dimensions and morphology) is key in its utilization for pulp and paper as well as composites. This study assessed the effect of age on the fibre properties of rubberwood. Samples of wood at four ages (10, 15, 20 and 25 years) were obtained at both the axial (base and top of merchantable length) and radial direction (innerwood, middlewood and outerwood). Slivers were obtained from the samples and macerated to provide individual fibres for optical measurement. Fibre dimensions at the four ages were measured, and their morphology was determined. Fibre properties and morphology were significantly affected by age at p = 0.05. Average fibre length was 1.47 ± 0.12 mm, with non-constant variation observed across the different ages, and from pith to bark. Average lumen width was 16.87 µm, and fibre diameter ranged from 25.02 µm to 27.23 µm. The fibre properties of rubberwood potentially make it suitable for pulp and paper production as well as wood composite boards. [ABSTRACT FROM AUTHOR]

The objective of the study is to evaluate the properties of the plywood made from rubberwood veneers thermally treated at various temperatures. Rotary-peeled rubberwood veneers were thermally treated at 160, 170, 180, and 190 °C under 1 bar pressure. 5-ply plywood panels were produced using melamine urea formaldehyde (MUF) resin as binder. Dimensional stability, i.e., water absorption (WA) and thickness swelling (TS) as well as mechanical properties of the plywood were assessed. The results demonstrated that the dimensional stability of the plywood made from thermally treated rubberwood veneers improved as indicated by lower WA and TS values. The reduction in WA and TS values increased along with treatment temperatures. Darkening in the plywood as a result of heat treatment was observed. Meanwhile, heat treatment at 170 °C and 180 °C resulted in plywood with the highest modulus of rupture (MOR), modulus of elasticity (MOE) and shear strength. However, beyond that temperature, the mechanical strength of the plywood started to decline. Based on the findings in this work it appears that heat treatment of rubberwood veneers at temperatures ranging from 160 to 180 °C could have a potential to improve overall properties of plywood panels. [ABSTRACT FROM AUTHOR]

Wood bark is a source of extractives with potential for valorization based on their chemical functionalities. In this study, Acacia mangium bark was extracted with distilled water. Then bark extract solutions in distilled water at various concentrations (5%, 10%, 15%, and 20% w/w) were vacuum impregnated into rubberwood. The color of the impregnated rubberwood was observed. The retention of bark extract in rubberwood and weight percent gain (WPG) from it were calculated. The morphology, dimensional stability, resistance to fungal decay, and subterranean termite resistance were determined for impregnated rubberwood samples. It was found that a higher concentration of bark extract gave higher retention and WPG in vacuum-impregnated rubberwood. The color of impregnated wood got darker with the concentration of bark extract, from light brown to red brown and dark brown. The bark extract penetrated all the way to the center (in thickness direction) of the wood and remained in lumens of vessels, parenchyma, and ray cells. The bark extract can improve dimensional stability of rubberwood. Weight loss caused by the fungi Trametes versicolor and Gloeophyllum striatum decreased with retention of bark extract in the impregnated wood. The bark extract may be toxic to termites (Coptotermes gestroi) that consumed impregnated wood: termites died during the third and fourth weeks after they attacked wood impregnated with bark extract at 15% or 20% concentration. [ABSTRACT FROM AUTHOR]

This study was carried out to examine the effectiveness of wood extract Tectona grandis (Teak) as preservative material against brown rot fungi on rubberwood. This is with a view to making rubber wood more resistant to fungi using an environmentally friendly treatment method like the natural extractives from Teak wood. The heartwood samples of Tectona grandis were extracted in hot water and used in the treatment of rubber wood. Samples of rubberwood were prepared in dimensions of 20mm x 20mm x 9mm for fungal tests. Before the fungal tests, rubberwood samples were oven-dried at 105°C till constant weight was attained. Teak heartwood was extracted using hot water and some of the oven-dried rubberwood samples were soaked in the extract for 24 hours. The chemical constituents of leached extracts of Teak heartwood were analyzed using the Gas Chromatography-Mass Spectroscopy (GC-MS) method. The unextracted and extracted Teak samples (in the same dimension as the rubberwood samples for fungal tests), rubberwood samples soaked in Teak extracts and untreated rubberwood were all exposed to brown-rot fungus (Serpula lacrymans) for seven weeks. Visual ratings of the spread of the fungus mycelium on the samples were recorded weekly, while the weight loss due to fungal exposure was calculated after the exposure period. The density value of Tectona grandis wood samples (816.99kg/m3) was higher than the value (573.80kg/m3) reported for Hevea brasiliensis wood samples. Rubber wood was not dimensionally stabilized after treatment with Teak extracts (47%) as the water absorption values of rubber wood were not significantly different from those soaked in water (49%). However, rubber wood treated with Teak extracts showed higher resistance to brown-rot fungi (10.11%) compared to the untreated samples (24.89%). This result indicated that the treatment of rubber wood with Teak extracts enhanced its resistance to brown-rot fungi, and the level of protection may have been conferred by the presence of some chemicals compounds such as saponin and tannin in the extracts of Teak heartwood wood. This study has shown that it is feasible to extract Teak heartwood as a bio-preservative to improve the resistance of other non-durable wood species. [ABSTRACT FROM AUTHOR]

Biochar, the product obtained by the pyrolysis of organic materials with little or no available air, acts as a long-term recalcitrant source of organic carbon when applied to soil. In the present study an in-farm method has been standardized for the pyrolytic conversion of four indigenous biomass resources into biochar. The biomass feedstocks viz. bovine bone (BB), coconut shell (CS), rubberwood (RW) and water hyacinth (WH) were dried and subjected to proximate, ultimate, biochemical analysis and were subjected to slow pyrolysis (563oC). The biomass feedstocks showed an ash content ranging from 1.04-61.23%, moisture content of 8.46-20.83%, volatile matter of 27.92-74.92% and fixed carbon of 1.17-18.75%. The biochar yield was maximum for BB (56.65%). Scanning electron microscope analysis of the biochar samples showed aligned honeycomb like groups with the greatest porosity (3.90-8.43 µm) in WH biochar. X-ray spectroscopy (EDX) analysis showed highest number of elements in WH biochar. The electrical conductivity, bulk density and water holding capacity of the biochars ranged from 102.56-7569.03 µs cm-1, 16.83-72.58 g cm-3 and 57.89-431.17%, respectively. The Fourier Transform Infrared spectrometer (FTIR) analysis of biochar samples showed several functional groups which help them to act as a good soil conditioner. Characteristics of the biochar produced from these biomass wastes revealed its potential as good soil conditioners in crop production systems.

Indonesia is one of the major natural rubber-producing countries. The low rubber prices severely affect rubber agribusiness as farmers and rubber companies depend on latex as the only source of income. This condition leads to an unprecedented challenge to rubber agribusiness sustainability. This systematic review aims to encourage the use of part of rubber plants as a source of revenue for rubber plantations to maintain their sustainability. Non-latex parts of the rubber plant can be utilized, including latex serum and skim waste, parts of rubber seeds, and rubberwood. The strength of the ancillary product of Hevea brasiliensis is that the raw materials are abundant, yet the weakness is that the rubber companies have no experience exploiting them. The opportunity for utilizing is widely open, as many methods have been researched; however, the main thread is how to compete with the existing products. Therefore, careful market research and feasibility studies are recommended.

Rubberwood was modified using a two-step process involving impregnation with maleated lignin (ML) followed by densification. The effects of ML modification and densification on the physical and mechanical properties of modified wood were studied. The successful preparation of ML was confirmed using Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. In addition, scanning electron microscopy was used to characterize the densified rubberwood structure, which featured fully compressed cell walls and cell lumina filled with ML. The rubberwood modification resulted in a more uniform structure and increased density compared to untreated wood. Further, water immersion and moisture absorption experiments revealed thickness swelling of only 27.7% and 20.9%, a reduction of nearly 76% and 55%, respectively, compared to the densified wood that was only impregnated with water. The ML modification can alleviate the embrittlement of wood caused by densification. The modulus of rupture and modulus of elasticity of ML-treated and densified wood improved by nearly 54% and 200%, respectively, compared to untreated wood. Therefore, the synergistic treatment strategy can contribute to the high-value utilization of low-quality rubberwood. [ABSTRACT FROM AUTHOR]

Hydrothermal treatment is an efficient and environmentally friendly method of enhancing the dimensional stability and durability of wood. The destructive effects of formic and acetic acids generated during thermal treatment, on the other hand, are known to have a negative impact on wood strength. As a result, hydrothermal treatment in different buffered media (acidic, neutral, and alkaline buffer) was performed in this study to mitigate the effects of the acids. As heating media, acidic buffer (pH 4 and 6), alkaline buffer (pH 8 and 10), and tap water (pH 7.43) were used to treat rubberwood at three different temperatures (160 °C, 180 °C, and 200 °C). The effects of different buffered media and treatment temperatures on the chemical components, crystallinity, and morphological changes in treated and untreated rubberwood were studied. The results of the experiments revealed that the chemical constituents of rubberwood changed along with the pH of the buffered media and treatment temperature. Rubberwood treated in alkaline media showed the least degradation, whereas water medium caused the most severe degradation. The crystallinity of wood increased initially (from 160 to 180 °C) and then decreased further at 200 °C. In addition, minimal damage to the wood cell was observed in an alkaline medium. [ABSTRACT FROM AUTHOR]

Internal stress (IS) development in juvenile and mature rubberwood during drying has been studied using an online measurement of a restoring force (RF) required to restrain a half-split rectangular wood specimen. According to an abrupt change in the restoring force rate, the evolution of IS can be divided into four distinct regimes, i.e., (i) zero IS, (ii) accelerating IS, (iii) reversing IS and (iv) decelerating IS. In stage I, the wood moisture content (MC) is still above fiber saturation point (FSP) with no drying shrinkage. In stage II, the negative RF constantly accelerates. IS mainly develops due to drying shrinkage with the activation energy of 19 kJ/mol. In stage III, the negative RF sharply decelerates and later reverses to the positive value. This regime takes place as the dried zone moves inwards and ends when there is no wet zone left. The stress reversal phenomenon having the activation energy of 36 kJ/mol contains two negative maxima, which occur faster in mature wood than in juvenile wood. Possible creep relaxation due to shear deformation of hemicellulose/lignin matrix between the cellulose fibrils is discussed. Finally, the positive RF decelerates in stage IV with the RF rate gradually declining and remaining at zero up until the end of drying. The corresponding activation energy of stage IV is 52 kJ/mol for both juvenile and mature rubberwood. [ABSTRACT FROM AUTHOR]

Kanyakumari district of Tamil Nadu is a significant producer of natural rubber in India. However, rubber cultivation is slowly becoming less profitable for the growers. Scientific research greatly aids in understanding the threats and opportunities to the development of any industry. The present study reviews the research carried out on the rubber plantations of the district. The low research interest and the research lacuna in rubber plantations of the district are identified. There is no previous research on the properties, utilization, or potential applications of rubberwood in the district. Underutilization of rubberwood can be considered a primary reason for the gradual decline of interest in rubber plantations of the district. Despite its uniqueness and good structural properties, people still view rubberwood as a waste or by-product. It has been mainly used as firewood or in single-use applications which require low or no value addition. Theoretical quantitative assessment of the district's rubberwood was done due to the absence of data. The present value of rubberwood in the district is understood from levels of value addition. This study serves as a base for further research by providing an overview of the rubber plantations in the district with detailed insight into rubberwood utilization. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the effect of acetylation on equilibrium moisture content (EMC) of Nigerian-grown rubberwood and its effect on colour change in exposure of rubberwood to surface degradation through accelerated weathering. The samples were modified to two levels of acetylation, which yielded weight percent gain (WPG) of 7 % and 10 % after 8hr (8-hr Acetyl) and 48hr of acetylation (48-hr Acetyl), respectively. Accelerated weathering of unmodified (Ref) and acetylated wood was done using QUV-Accelerated Weathering Tester for four weeks. The unmodified and acetylated samples (weathered and unweathered) were oven-dried and conditioned in climate rooms at different relative humidity of 50 %, 65 % and 95 %, with samples being moved to each room after 14 days. Results showed that acetylation led to a significant decrease in equilibrium moisture content of rubberwood. After weathering, there was a decrease in EMC of rubberwood due to removal of hemicelluloses alongside the degraded lignin, and a slight increase in EMC of the acetylated wood. In terms of colour change, photo-bleaching of the acetylated samples was higher (10.46 for 48-hr Acetyl) after four weeks of weathering compared to the unmodified samples (6.43). Hence, the outcome of this study has shown that, although acetylation is effective in minimizing moisture ingress into wood, it resulted in photo-bleaching of the weathered samples. Additional surface coating is recommended to serve as a protective layer, preventing partial washing out of the acetyl groups, minimize photo-bleaching during weathering and prolong the aesthetic value of the wood especially in outdoor applications such as wall cladding and façade.

The development of low-environmental-impact technologies for the elimination of biological damage is one of the vital goals of the wood protection industry. The possibility of utilizing pyroligneous acid as a wood preservative can be a great solution to extend the application of the currently fast-growing timber species, which has lower natural durability against biological damage. In this study, the effectiveness of pyroligneous acid as a wood preservative was evaluated by impregnating rubberwood with pyroligneous acid using vacuum-pressure treatment, and the treated woods were exposed to mould fungi, wood-decay fungi and termite attacks under laboratory conditions. Pyroligneous acids produced from rubberwood (RWPA) and oil palm trunk (OPTPA) at different pyrolysis temperatures were evaluated. To fully understand the effectiveness of pyroligneous acids as wood preservatives, different concentrations of pyroligneous acids were impregnated into rubberwood. Concentrations of 50% RWPA and 30% OPTPA were sufficient against mould and decay fungi on rubberwood. Rubberwood impregnated with pyroligneous acid acted as a slow-acting toxic bait to cause a high termite mortality rate due to toxic feeding and does not serve as a good repellent to prevent termites from feeding on the wood. In general, OPTPA has better biological durability compared to RWPA. [ABSTRACT FROM AUTHOR]

Lab-scale torrefaction experiments of Rubberwood and Gliricidia were conducted at 250-300 oC and 30–60 min in a nitrogen environment to understand the torrefaction behavior. TGA and FTIR were used to characterize raw and torrefied biomass. In the lab-scale experiments, Rubberwood showed 16% mass loss, whereas Gliricidia showed 25% mass loss under the most severe conditions, resulting in 9% and 22% volatile drop, respectively. The higher heating value of the torrefied product increased from 18.9 MJ/kg to 21.39 MJ/kg for Rubberwood and from 19.46 MJ/kg to 22.44 MJ/kg for Gliricidia under the most severe conditions. The calculated Energy Mass Co-benefit Index (EMCI) of Rubberwood at 275 °C and 60 min or 300 °C and 45–60 min and Gliricidia at 300 °C and 60 min indicated favorable torrefaction conditions. Comparatively, Gliricidia was performing well in torrefaction. The severity factor was modified by finding the optimum fitted parameter ω, which establishes a feedstock-specific relationship between torrefaction severity and operating conditions. The normalized severity factor shows a linear correlation with the properties of torrefied biomass, which could facilitate torrefaction modeling. [ABSTRACT FROM AUTHOR]

The bending performance of wood is important for its application in furniture, and it is one of the criteria used to assess the suitability of a particular wood species for furniture. In this context, the steam-bending and surface roughness characteristics of four forest plantation wood species were evaluated. One batch of wood specimens were subjected to both surface roughness experiments using the stylus and toluene spread methods, while another batch of the wood specimens were subjected to steaming, clamped, and bent using a circular shape mold. The instantaneous spring-back was measured after 10 days, while the springback over time was measured from days 15 to 65. The surface roughness experiments showed that the Hevea brasiliensis had the lowest surface roughness, followed by the Eucalyptus pellita, Acacia mangium, and finally Revotropix paulownia. In terms of the bending performance, it was found that only the H. brasiliensis achieved the threshold 95% satisfactory level based on visual ranking. Furthermore, the wood species also recorded the lowest spring-back, both instantaneous and over-time, to register the best bending performance. On the other hand, R. paulownia had the worst bending performance, primarily due to its low density. [ABSTRACT FROM AUTHOR]

The dimensional instability of rubberwood [Hevea brasiliensis (Willd. ex A. Juss.) Müll. Arg.] is one of the major drawbacks that limits its utilization. Therefore, treatment is needed to improve these properties. Hydrothermal treatment in different buffered media is one of the techniques that improve its dimensional stability. The physical properties of hydrothermally treated rubberwood in different buffered media (pH 4, 6, 8, 10) and tap water (pH 7.43) with different temperatures (160 °C, 180 °C and 200 °C) were studied. In this study, physical properties such as equilibrium moisture content (EMC), density (ρ), mass loss (ML), water absorption (WA), volumetric swelling coefficient (VSC), thickness swelling (TS) and anti-swelling efficiency (ASE) were investigated for both treated and untreated specimens. Both the buffered media and temperature significantly affected the physical properties. The results indicated that the EMC (%), ρ (kg/m3), ML (%), VSC (%), TS (%) of treated rubberwood samples reduced as the treatment temperature increased. With the exception of WA (%), as WA increased when the treatment temperature increased from 160 °C to 180 °C but started to decrease when the temperature was further increased to 200 °C. The research study also exhibited that hydrothermal treatment using buffered media at different temperatures enhanced the dimensional stability of the treated samples. Alkaline media gave the best results on the physical properties compared to other treatment medias. [ABSTRACT FROM AUTHOR]

This research aimed to evaluate particleboards produced with bean straw and rubberwood particles glued with vegetable polyurethane adhesive as a proposal for a sustainable insulating material. Therefore, the physical, chemical, and mechanical properties of the panels were determined, as well as their resistance to termite attack, combustibility, and thermal insulation. By increasing the bean straw particle content, the water absorption was significantly reduced (from 11.44 % to 7.68 %), with the same tendency observed for thickness swelling (from 4.61 % to 1.73 %) after 24 h of immersion. Panels produced with 25 and 75 % bean straw contents showed an end to thermal degradation before rubberwood-only compounds, being more resistant to combustion. There was a reduction in the modulus of elasticity (66.4 %) and modulus of rupture (52.5 %) due to the increase in the bean straw particle content. The evaluation of the resistance of the particleboard to dry wood termites showed a lower mass loss for composite panels with higher contents of bean straw. The thermal conductivity of particleboards showed that greater amounts of waste resulted in greater thermal insulation. In terms of generating sustainable products and meeting the needed properties, it was concluded that it is feasible to produce particleboards with agricultural wastes and formaldehyde-free adhesive. • Bean wastes were used as a substitute for rubberwood in particleboards. • Particleboards with environmentally friendly castor oil-based adhesive were studied. • The chemical properties of bean wastes influenced the properties of particleboards. • The thermal insulation of the panels improved with higher waste levels. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the production and properties of mixed pellets made from rubberwood (Hevea brasiliensis Muell. Arg) and refuse-derived fuel (RDF) waste with no added binder. Three different conditions of mixed pellets were developed to compare their chemical and physical properties to rubberwood pellets. The produced samples were subjected to both ultimate and proximate analyses. The contents of C, H, N, S, and Cl significantly increased with the increasing amount of refuse-derived fuel in the samples, resulting in reduction of the volatile matter. The mechanical durability of the pellet samples ranged between an average value of 98 and 99%. Mixed pellets containing 50% of rubberwood and 50% of refuse-derived fuel have improved heating values by 22.21% compared to rubberwood pellets. Moreover, mixed pellets having 50% of wood and 50% of refuse-derived fuel had the highest density and the highest energy compared to the other samples. Based on the findings of this study, it appears that the manufactured mixed pellets have the potential to be used as high-energy fuel. [ABSTRACT FROM AUTHOR]

Defects in rubberwood is a major problem in the rubberwood industry of Thailand. It was detected during the drying process of rubberwood which caused bow and crook deformations. The current study presented a model that described the change in the magnitude of bow and crook between two moisture contents below the fiber saturation point. The longitudinal shrinkage in the experimental samples was obtained at the moisture content range from 16% to 8%. The model showed that the variation in longitudinal shrinkage coefficient over the cross-section and along the sample could explain most of the changes in bow and crook of the lumber. In addition, it was possible to identify evenly-curved bow and crook. The least value of root mean square error was at 0.115 and standard error of 0.130 for sample 3A1 and root mean square error of 0.179 and standard error at 0.202 for sample 7B3 indicated that these samples had the best model predictions. The model was able to predict the changes in bow better than the changes in crook. Both mechanical and colour properties were comparable to the work of others. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate some of the properties of experimental wood plastic composite (WPC) panels manufactured from a low percentage of rubberwood (Hevea brasiliensis Muell. Arg), waste polyethylene terephthalate (PET) and silica at three different ratios. It was determined that water absorption values of the samples decreased with the increasing amount of PET in the panels. The lowest absorption value of 0.34% was determined for the samples having 40% PET in their content as a result of 24-h soaking. The highest hardness value of 4492 N was found for the samples made with the combination of rubberwood, PET and silica at 10%, 40% and 50%, respectively. The compressive strength of WPC specimens also followed a similar trend with the hardness characteristics of the panel and improved with increasing PET percentage. Statistical analyses revealed that values of compression strength, hardness, 2-h and 24-h water absorption of the specimens made with 20, 30, and 40% PET content resulted in significant difference from each other (p ≤ 0.0001). Based on the findings in this study it appears that increasing silica content in the samples adversely influenced their mechanical properties while creating a certain level of enhancement of water absorption of the specimens. It seems that using a combination of waste PET and a limited amount of silica with a low percentage of wood particles could have the potential to produce value-added environmentally friendly composites to be used for different applications. [ABSTRACT FROM AUTHOR]

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The properties of the laminated veneer lumber (LVL) composed of the boiled veneer of Rubberwood (Hevea brasiliensis) using polyvinyl acetate (PVAc) adhesives in various cold-pressing time and various conditioned time with loaded and unloaded were studied. Five-ply LVL was produced by boiling veneer at 100°C for 90 min as pretreatment and cold-pressing time at 12 kgf cm−2 for 1.5, 6, 18, and 24 h then conditioned at 20°C and 65% relative humidity (RH) with loaded (12 kgf cm−2) and unloaded for 7 days as physical treatment. Especially for the delamination test, the specimens were immersed at 70 ± 3°C for 2 h and dried in the oven at 60 ± 3°C for 24 h; then, the specimens were solidified at room temperature (20°C and 65% RH) with loaded (12 kgf cm−2) and unloaded for 7, 10, 12, and 14 days. To determine the performance of LVL, the density, moisture content (MC), delamination, modulus of elasticity (MOE), modulus of rupture (MOR), horizontal shear strength, and formaldehyde emission tests were conducted according to the Japanese Agricultural Standard (JAS 2008) for structural LVL. The MOE and MOR values were significantly influenced by the physical treatment, however, neither to horizontal shear strength nor to formaldehyde emission. The best performance of LVL has resulted from unloaded LVL with cold-pressed time for 18 h; the MOE and MOR values were 9,345.05 ± 141.61 N mm−2 and 80.67 ± 1.77 N mm−2, respectively. The best value of the horizontal shear strength was obtained from the LVL with 18 h cold-pressing time and conditioned with loaded (13.10 ± 1.47 N mm−2) and unloaded (12.23 ± 1.36 N mm−2). The percentage of delamination values decreased with an increase in the cold-pressing time and conditioning time. The lowest value of delamination (19.06%) was obtained from the LVL with 24 h cold-pressing time and conditioned with loaded for 14 days. Except the delamination test, all other properties fulfilled the JAS.

Abstract Heat treatment was an eco-friendly modification technology for rubberwood, without the addition of chemical reagents into the wood and wood performance has been improved remarkably. Many effluents are generated from heat-treated rubberwood process, which were rarely researched. The effluents contain relatively high content of volatile organic compounds, which may seriously threaten the environment and human health. In this study, effluents condensated during different heat-treated stages (125 ℃, 145 ℃, 175 ℃, 185 ℃, 215 ℃) and frequently used industrial heat treatment production technology (185 ℃/3 h, 215 ℃/3 h) were characterized by gas chromatography–mass spectrometry (GC–MS). The effluents were classified as aldehydes, phenols, esters, ketones, acids, alcohols, alkanes, anhydride, aromatics and compounds released the most during all heat-treated stages were aldehydes. With the temperature increased, the relative amounts of aldehydes decreased, while the ketones, esters and aromatics increased under acidic constituents (pH ranged from 4.17 to 2.47) and high moisture condition. The vanillin and coniferyl aldehyde accounted for much higher proportion in the aldehydes. The mass loss of rubberwood was larger under 215 ℃/3 h (16.61%), correspondingly the effluents had more kinds of compounds at 215 ℃. These results would provide guidance for research of effluent disposal and transform biomass residues into valuable things.

Abstract Blue staining on rubberwood (Hevea brasiliensis) is a common kind of defect. There currently exists much research focused on the prevention and control of blue staining. However, little research has been concentrated on the utilization of blue staining for green dyeing. The research conveyed in this paper primarily used Lasiodiplodia theobromae to dye rubberwood, and used scanning electron microscope (SEM), energy-dispersive spectrometer (EDS), X-ray diffraction (XRD), and fourier transform infrared spectrometer (FTIR) to analyze the commission internationale eclairage (CIE) L*a*b* value of color, the contact angle, the pH value, 24-h water absorption, mass loss ratio, and compressive strength in increments between 5 and 40 days. The results found that the color of rubberwood became darker and more uniform, and that the surface dyed with fungi can reach a super-hydrophobic state. With the increase of time, the pH value of rubberwood changed from acidic to alkaline. Furthermore, hyphae entered the wood mainly through vessels for their large pore diameter, and reduced water absorption. Mass loss ratio increased gradually between 5 and 40 days. The research in this paper concludes that the microorganism was an effective method of wood dyeing, and lays a foundation for further research.

This paper aimed to investigate the temperature dependence of thermal conductivity of heat-treated rubberwood (HTR). Rubberwood specimens were thermally treated at 180°C with three different durations of 15, 25 and 35 h, respectively. Thermal conductivity values of HTR at various mean temperature ranges were then examined. That of untreated rubberwood (UTR) was also measured as a comparison. The result showed that thermal conductivity of UTR and HTR increased with increasing temperature for all durations as a linear relationship in which the values of HTR were lower at all examined temperatures. The rate of change of thermal conductivity with temperature of HTR for durations of 15 and 25 h and UTR was similar (∼0.0004 W/mK/°C). However, rubberwood heat treated for 35 h was much less sensitive to temperature compared with the UTR, showing a relatively small change of thermal conductivity with temperature (∼0.0001 W/mK/°C), which is comparable to typical insulation materials. This indicates that heat treatment could improve the thermal stability of rubberwood subjected to varying temperatures. In view of environmental and energy concerns, HTR should therefore be considered as one of the best potential raw materials for energy efficient building construction. [ABSTRACT FROM AUTHOR]

Rubberwood (Hevea brasiliensis) is a major raw material used in furniture factories in southern Thailand. Proper kiln drying of the lumber plays a significant role on the efficient utilization of the final product. Overall quality-reducing defects in such a materials are inevitable, unless a correct and proper drying process is used. Therefore, the objective of the present study was to develop a three-dimensional numerical model of heat and moisture transfer during the drying process and to conduct physical experiments in order to compare the results between the two approaches. For this purpose, an innovative kiln dryer was designed in the laboratory which will also contribute to the prevention of defects in the wood. The results show that the samples dried at a temperature of 120 °C experienced faster decreases in their moisture content compared to those dried at temperatures of 100 °C and 80 °C. The drying temperature and moisture content of the samples were successfully predicted by the simulation model created in this investigation and the two approaches demonstrated good agreement for temperature and moisture with root mean square errors of 0.50 and 0.19, standard errors of 0.38 and 0.16, and mean absolute errors of 0.94 and 2.18, respectively. These results will help rubberwood drying facilities prevent wood deformation while reducing the drying time required. [ABSTRACT FROM AUTHOR]

Light induced darkening and deterioration of wood used outdoors is undesirable. Photoprotection of wood could be achieved by using additives that reflect or absorb harmful radiation responsible for degradation. Nano metal oxides have strong absorption in the UV range of solar radiation and good transparency in the visible region. They offer unique benefits in protecting coatings and coated substrates from being degraded by UV radiation. However, to exploit the properties of nanoparticles, homogenous dispersion without agglomeration is necessary. In the present work, the photostabilization of rubberwood surfaces coated with cerium oxide (CeO2) was studied. The nanoparticles were surface functionalized with an organic alkoxy silane (3-glycidyloxypropyltrimethoxy silane) to improve the homogenous distribution in coatings, and the modified nanoparticles were dispersed in isopropanol and polyurethane (PU) coating. Rubberwood surfaces coated with dispersed nanoparticles (concentration 0.5 % to 6 % w/v) were exposed to a fluorescent UVA light source (λ=340 nm) at 60 °C in an accelerated weathering tester for 500 h and 1000 h. Colour changes due to UV light exposure were monitored using a spectrocolourimeter. Dispersion of CeO2 nanoparticles in PU coatings (concentration >2 %) restricted the photoyellowing of wood polymers.

This study aimed to reduce the loss of mechanical strength in heat-treated rubberwood by rapid cooling. Heat-treated rubberwood specimens were prepared by controlling their cooling rate during the cooling phase of the heat treatment. The effects of cooling rate on the physical properties, chemical composition, and mechanical properties of heat-treated rubberwood were evaluated. Results indicated that cooling rate significantly influenced mass loss (ML). ML in heat-treated rubberwood cooled at 6 °C min−1 decreased by 23% relative to that in heat-treated rubberwood subjected to natural cooling. Compared with the heat-treated rubberwood subjected to natural cooling, the heat-treated rubberwood that was cooled at 4.5 °C min−1 increased in modulus of rupture (MOR), surface hardness, and screw withdrawal strength (tangential section) by 26, 8, and 16%, respectively. The cool rates exerted less effects on the dimensional stability, surface color, modulus of elasticity (MOE), compressive strength parallel to grain (CS), and screw withdrawal strength (radial section) of the heat-treated rubberwood. The application of rapid cooling to wood heat treatment could efficiently shortened the heat treatment period, thus increasing productivity. [ABSTRACT FROM AUTHOR]

In this study, the effects of rubberwood extractives on the mechanical properties and fungal decay resistance of rubberwood-based wood plastic composites (WPCs) were explored. Three different solvents, benzene-ethanol, methanol, and deionized water, were used to remove the extractives of the rubberwood flour (RWF). The surface topographies of the prepared rubberwood-based WPC and the rubberwood itself were characterized using digital instruments and scanning electron microscopy (SEM). The results indicate that the mechanical properties of the WPC prepared using extracted RWF were higher than those of the WPC prepared with unextracted RWF. The sequences of resistance to the growth of mold on the surface of the WPC were ranked as follows: deionized-water-extracted WPC > methanol-extracted WPC > benzene-ethanol-extracted WPC > unextracted WPC. The WPC made with extracted RWF had better brown-rot resistance and worse white-rot resistance than the unextracted WPC. These results demonstrate that the removal of rubberwood extractives has a positive effect on the mechanical properties and mold and fungal decay resistance of rubberwood-based WPCs. [ABSTRACT FROM AUTHOR]

This research was aimed to investigate mechanical properties, color and cell-wall components changes, and durability of pre-dried rubberwood (Hevea brasiliensis) after superheated steam (SS) treatment. Wood samples were treated at different SS temperatures (140–180°C) for 1–3 h. The highest compression strength parallel-to-grain, hardness and impact strength were found for samples treated at 160°C for 3 h (30.7% higher than untreated), at 150°C for 1 h (26.6% higher than untreated) and at 150°C for 2 h (52.6% higher than untreated), respectively. The surface color became darker after each treatment in comparison with the untreated wood. The number of accessible hydroxyl groups decreased and the relative cellulose crystallinity increased with SS temperature, indicating decreased hygroscopicity of the treated wood. Also, SEM micrographs of wood surface showed consistent decrease in starch particles with treatment temperature. Both decay and termite resistances of treated rubberwood improved with treatment temperature. All the analyzes showed that dried rubberwood treated with SS had some improvements in the mechanical properties, decreased hygroscopicity, and increase resistance to decay. [ABSTRACT FROM AUTHOR]

The objectives of this study were to evaluate some of physical and mechanical properties of rubberwood (Hevea brasiliensis) as function of microwave heat treatment process. The specimens were heat treated at three temperature levels of 150 °C, 180 °C, and 220 °C for 20 min in a small microwave oven connected to a computer. Bending characteristics, namely modulus of elasticity (MOE), modulus of rupture (MOR) as well as hardness of the samples were tested. Dimensional stability in the form of swelling and water absorption of the specimens were also determined. Based on the findings in this work it appears that microwave can be used successfully for heat treatment of rubberwood. Overall mechanical properties of the samples were adversely influenced by the treatment. MOE, MOR and hardness values of the samples treated at a temperature of 220 °C had 2.37, 3.69, and 2.12 times reduced than those of control samples, respectively. Dimensional stability of the heat treated samples as a result of 2-h and 24-h water soaking improved. Micrographs take from scanning electron microscope (SEM) and transmission electron microscope (TEM) revealed that certain amount of damage took place in the cellwall of the treated specimens. Overall discoloration on the samples due to microwave heat treatment was found insignificant. [ABSTRACT FROM AUTHOR]

Heat treatment was an eco-friendly modification technology for rubberwood, without the addition of chemical reagents into the wood and wood performance has been improved remarkably. Many effluents are generated from heat-treated rubberwood process, which were rarely researched. The effluents contain relatively high content of volatile organic compounds, which may seriously threaten the environment and human health. In this study, effluents condensated during different heat-treated stages (125 ℃, 145 ℃, 175 ℃, 185 ℃, 215 ℃) and frequently used industrial heat treatment production technology (185 ℃/3 h, 215 ℃/3 h) were characterized by gas chromatography–mass spectrometry (GC–MS). The effluents were classified as aldehydes, phenols, esters, ketones, acids, alcohols, alkanes, anhydride, aromatics and compounds released the most during all heat-treated stages were aldehydes. With the temperature increased, the relative amounts of aldehydes decreased, while the ketones, esters and aromatics increased under acidic constituents (pH ranged from 4.17 to 2.47) and high moisture condition. The vanillin and coniferyl aldehyde accounted for much higher proportion in the aldehydes. The mass loss of rubberwood was larger under 215 ℃/3 h (16.61%), correspondingly the effluents had more kinds of compounds at 215 ℃. These results would provide guidance for research of effluent disposal and transform biomass residues into valuable things. [ABSTRACT FROM AUTHOR]

Rubberwood drying is an energy-intensive process where drying defects are the main problems faced by the wood industry. The main objective of this study is to evaluate the coefficient of thermal expansion (CTE) of rubberwood to have a better understanding of the effect of temperature over the distortions of rubberwood during drying. Rubberwood samples were first dried at three different hot air temperatures and the mechanical properties of dried rubberwood samples were tested in the preliminary experiment to determine the suitable temperature condition for further evaluation of the CTEs of rubberwood samples. The CTEs of rubberwood in tangential and radial directions were evaluated through strain gages at three different moisture content (MC) levels: above 60%, at 12% and almost 0% (dry state). Based on the findings of this work, the CTEs of rubberwood in the tangential direction were found to have higher values than that of radial direction. The rubberwood samples had the highest CTEs values at 12% MC in both directions. Also, no significant differences were found between the experimental and expected CTE values of rubberwood as a function of specific gravity in the dry state. [ABSTRACT FROM AUTHOR]

A 50:50 kenaf core to rubberwood ratio were used to fabricate low-density fibreboards. Firstly, the fibres were co-refined at 180 °C for 10 min. Refined fibres were sieved on six levels of size distribution. Results on fibre size distribution concluded that the co-refined fibres were similar in size, in comparison to commercial rubberwood fibres. Low-density fibreboards were fabricated using the admixture of both rubberwood and kenaf core fibres. The results showed that board density played a greater role in producing high quality lightweight fibreboard rather than resin content. The study also revealed that low density fibreboards with acceptable properties could be successfully produced. Low-density fibreboards (550 kg m-3) had comparable physical and mechanical properties to those of commercial MDF (720 kg m-3). Nevertheless, a slightly higher resin content of 14% is needed, in comparison to the commercial MDF. Combining kenaf core and rubberwood fibres improved the internal bonding strength significantly. A total of 80% of the low-density fibreboards produced in this study passed the British Standard 622-5: 2009 even at a board density as low as 350 kg m-3. [ABSTRACT FROM AUTHOR]