Determination of fiber length and juvenile and mature wood zones from Hevea brasiliensis trees grown in Brazil

The aim of this study was to verify the average fiber length and the juvenile and mature wood zones from Hevea brasiliensis proveniences from a reforestation area in Sao Paulo, Brazil. For this purpose, five Hevea brasiliensis trees were randomly collected from a 50-year-old plantation, located in Balsamo, Sao Paulo, Brazil. The trees were cut and five flat sawn boards were obtained. The juvenile and mature wood zones were determined by fiber length measurement from the pith to the bark. The results showed that: (a) the juvenile wood of this species occurred approx. between 40 and 55 mm, from the pith, and from this point forward, the mature wood zone was found; (b) there was a significant difference between the average fiber length of juvenile wood (1.26?mm) and mature wood (1.51?mm).     

Surface characteristics and overlaying properties of flat-pressed wood plastic composites

This study evaluated surface characteristics and overlaying properties of wood plastic composite (WPC) panels made from dry-blended rubber wood fiber-polypropylene (PP) powder formulations using a conventional flat-press process under laboratory conditions. Three levels of rubberwood fibers (Hevea brasiliensis), 40%, 50%, and 60%, based on the composition by weight, were mixed with the PP powder without and with 3% (based on weight) maleic anhydride grafted PP (MAPP) as a coupling agent. Contact angle measurements on the WPC samples were performed using a goniometer connected with a digital camera which collected one image per second. Roughness measurements, average roughness (R _a), mean peak-to-valley height (R _z), and maximum roughness (R _y), were taken from the sanded samples along and across the sandmarks using a fine stylus tracing technique. With increasing polymer content, surface roughness of the WPC panels improved while their wettability and adhesive bonding strength decreased. The formulations without MAPP were found to have higher surface roughness but they also had better wettability. Wettability and surface roughness of the WPC panels can provide good information on their ability to bond.     

Reaction of wood with inorganic salts

Wood samples and veneers of Hevea brasiliensis (Rubber wood) and Acacia auriculaeformis treated with aqueous solutions of chromium trioxide, ferric chloride and ferric nitrate were studied for water repellency and their reaction with wood constituents. FTIR spectra obtained from wood surface treated with chromium trioxide indicate the formation of a water insoluble complex between chromium trioxide and aromatic ring of lignin, whereas no reaction takes place with ferric salts. Treatment of wood by chromium trioxide was found to be effective in imparting water repellency in wood.     

Effect of radiata pine juvenile wood on the physical and mechanical properties of oriented strandboard

This work analyzes the impact of radiata pine (Pinus radiata D. Don) juvenile wood on the physical and mechanical properties of oriented strandboards (OSB). Radiata pine logs were obtained from 10 trees of a 26-year old managed stand located in the 8th Region of Chile. The experimental design considered the proportion of juvenile wood and strand orientation as independent variables. OSB panels of 0.4 m×0.4 m×12 mm were produced and tested. The results show that the juvenile wood proportion has a significant impact on the physical and mechanical properties of OSB. Strands orientation had a significant impact on all the properties studied with the exception of the modulus of elasticity in bending. However, this impact was small in all cases and would not change panel grade with the exception of linear expansion. In this case, panels made from tangential strands showed a higher linear expansion. According to these results, radiata pine juvenile wood can be used for the manufacturing of OSB up to a proportion of 70% of the oven-dry wood weight without significant losses of the physical and mechanical properties if the juvenile wood strands are located in the surface layers.     

Rapid characterisation of brown and white rot degraded chir pine and rubberwood by FTIR spectroscopy

Pinus roxburghii (chir pine) and Hevea brasiliensis (rubberwood) were degraded by brown-rot (Polyporus meliae) and white-rot (Trametes versicolor and Trametes hirsuta) fungi. The modification in the chemical structure of degraded wood was monitored by FTIR spectroscopy. In wood decayed by brown rot, there was a progressive increase in the lignin content, which is evident from increase in the relative intensities of lignin associated bands and a corresponding decrease in the intensities of carbohydrate bands. In contrast, there was a decrease in the lignin content of white rot decayed wood. Both the white rots used in this study showed preferential degradation of lignin, which is indicated by a reduction in relative intensities of lignin associated bands.     

Use of tannin adhesive from Stryphnodendron adstringens (Mart.) Coville in the production of OSB panels

Stryphnodendron adstringens (Mart.) Coville is a species from the Cerrado (Brazilian tropical savanna) popularly known as barbatimão. Its main use of economic value lies in the extraction of the tannins found in its bark and leaves. The purpose of this study was to assess the technical viability of using a tannin-based adhesive coming from the bark of Stryphnodendron adstringens (Mart.) Coville for the production of Oriented Strand Board (OSB) panels. Tannin-based adhesives were produced from tannins extracted from the bark of barbatimão, and these adhesives were used in proportions of 0, 25, 50, 75 and 100 % with commercial urea–formaldehyde adhesive. The properties of the pure adhesives and the mixtures were determined. Subsequently, OSB panels were produced with urea–formaldehyde adhesives, tannin–formaldehyde adhesives and their mixtures. The panels were produced with wood from Pinus oocarpa, with 8 % adhesive, a press cycle of 40 kgf cm^?2, and temperature of 160 °C for a period of 8 min. Only the OSB panels produced with 100 % urea–formaldehyde adhesive, 100 % barbatimão tannin adhesive and 25 % barbatimão adhesive combined with 75 % urea–formaldehyde fulfilled all the pre-requisites stipulated in the standard EN 300 (2006) for type 1 panels, thus proving to be technically viable for application in OSB panels.     

Untreated Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) wood-panels exposed out of ground contact in Sweden for two years

In this study, the durability of 230 wood panels, consisting of both Scots pine (Pinus sylvestris) and Norway spruce (Picea abies), were examined in an above-ground durability field test, for two years, in southern Sweden. The samples consisted of three pieces of wood, 22×95×500 mm³. The pieces were screwed together with an overlap so as to obtain an efficient moisture trap. The results of the durability test showed large differences between Scots pine sapwood and heartwood. Sapwood displayed unacceptably high moisture contents and fungal discoloration, while heartwood had low and stable moisture contents, and lesser discoloring. Norway spruce had moisture dynamics similar to pine heartwood, although a some what higher moisture content was recorded. The differences in moisture dynamics among the spruce samples, which were divided into: juvenile wood, mature wood with horizontal annual rings, and mature wood with vertical annual rings, were small. Juvenile wood showed more discoloring caused by mould fungi. The samples with horizontal annual rings suffered massive cracks.     

Minimizing dust emission during routing operation of rubberwood

The study evaluated airborne dust emission (0.1–10 µm) during the routing operation of Rubberwood (Hevea brasiliensis) in the furniture industry in South East Asia. It was found that the average chip thickness of 0.1 mm and wood moisture content of 12–14% minimized dust emission, while the cutting tool rake angle had little influence on dust emission. The study shows that adverse economic implications due to health hazards posed by airborne dust emissions during wood machining can be reduced by manipulating the average chip thickness and work-piece moisture content.     

Water repellency in treatedHevea brasiliensis andMangifera indica wood

Samples of rubber (Hevea brasiliensis) and mango (Mangifera indica) wood treated with 2.5%, 5%, 7.5% and 10% aqueous solution of Chromic acid were assessed for water repellency and dimensional stability. Significant reduction in water absorption in treated samples was observed in initial five hours of soaking in water compared to untreated controls. It was found that effectiveness of water repellency was independent of concentration of solution under repeated cycles of wetting and drying. Degree of water repellency that could be achieved by chromic acid treatment appears to be dependent on constituents of wood.     

Effects of pre-steaming on the drying quality of Rubberwood

In this study, the kiln drying yield of 30 mm Rubberwood (Hevea brasiliensis) furniture stocks with pre-steaming treatment was evaluated. The results revealed that pre-steaming increased the permeability of the wood, hence increasing the drying rate while reducing drying defects. It was found that the pre-steaming treatment should be included in the drying of Rubberwood in order to reduce the overall drying costs as well as improving its quality.     

Some physical and mechanical properties of thermally modified juvenile and mature black pine wood

In this study, test samples of juvenile and mature black pine wood were treated for 3 h at temperatures of 140, 170, and 200 °C. Mass loss, density, equilibrium moisture content (EMC), modulus of rupture (MOR), modulus of elasticity, and impact bending strength (IB) of the separate samples were determined. The purpose of the tests was to determine how heat treatment at the three temperatures influenced the properties of the juvenile and mature wood. The results showed that heat treatment had greater effects on mass loss, EMC, and density of juvenile wood than of mature wood. The results also showed that heat treatment had lesser effects on the MOR, modulus of elasticity, and IB of juvenile wood than of mature wood. The results clearly indicated that heat treatment had different effects on the properties of juvenile and mature black pine wood.     

An assessment of Malaysian wooden furniture manufacturers’ readiness to embrace chain of custody (COC) certification

Although Malaysia is a major producer and exporter of wood products in the world, the status of wood products certification in the industry is relatively unknown. Therefore, a study was carried out to assess the status of chain of custody certification among wooden furniture manufacturers using a structured questionnaire to interview firms who had participated at the annual Malaysian International Furniture Fair (MIFF). Results collated indicate that the readiness to adopt chain of custody certification among wooden furniture manufacturers was low. The lack of price premiums, limited market potential and high cost was cited as the primary reasons deterring furniture manufacturers from adopting chain of custody certification. Furthermore, the use of plantation wood resources, such as Rubberwood (Hevea brasiliensis), perceived to be certified wood resources, reflects the lack of understanding among the manufacturers. This study shows that an increasing adoption of chain of custody certification among wooden furniture manufacturers in Malaysia can be realized in the market organisation, especially with regards to price premiums and market requirements.     

Relation of arabinogalactans to density, growth rate and shear strength in wood of cultivated Siberian larch

Present in high concentrations in the heartwood of Larix species, water-soluble arabinogalactans affect the density, moisture content and processing properties of larch wood. The aim of this study was to chart arabinogalactan concentration (AC) and to define the relations between arabinogalactans, and density and shear strength at different axial and radial locations in Larix sibirica Ledeb. trunks. In addition, growth rate (ring width, fibre dimensions) was compared with AC to determine the link between them. Although quite low AC levels were observed, values differed significantly between sapwood and heartwood, with a slight increasing trend from pith to mature heartwood. Variation in growth rate affected AC levels in juvenile wood only. In conclusion, AC levels were clearly lower in the studied cultivated, fast-grown Siberian larches than those measured earlier in trees of natural origin. AC had a weak correlation with growth rate and shear strength.     

Temperature charts of Hevea brasiliensis during log steaming and its effect on the board cracks

The temperatures of Hevea brasiliensis logs during the steaming process were determined and correlated with the cracks of the boards. Thermocouples were inserted at the center of the logs, and the temperatures were recorded inside the material during steaming at 54, 75 and 92 °C. Logs were cut and the cracks of the boards were measured. The results showed that: (1) the sigmoidal logistic model explains the variation of temperature in the logs; (2) the variation in the length of cracks between the peripheral boards and those taken near the pith were 194.6, 150.6 and 138.8 % for the material steamed at 54, 75 and 92 °C, respectively; and (3) the board’s cracks were smaller in the logs that reached the glass transition temperature. A chart to determine the steaming logs time as a function of the steam temperature and the desired temperature inside Hevea brasiliensis logs was developed.     

Optimizing the abrasive sanding process of rubberwood (Hevea brasiliensis)

The abrasive sanding process is the most labor-intensive operation in the Rubberwood furniture manufacturing industry. Although the machining properties of Rubberwood (Hevea brasiliensis) are well established, information on its abrasive sanding characteristics is sparse. This study was carried out to establish the optimal abrasive sanding regime for Rubberwood. The results suggest that the abrasive sanding process can be optimized when well machine-planed Rubberwood stocks are used. Further, it was found that when the machine surface quality was good, abrasive sanding with a two-level sequence of grit sizes was sufficient to produce an acceptable surface smoothness. The improved surface smoothness also minimized the coating film spread on the wood surface. This finding will serve as a useful benchmark for machine-planing and abrasive sanding processes in the high-volume Rubberwood furniture manufacturing industry.     

Influence of wood species on the perceived value of wooden furniture: the case of rubberwood

Zusammenfassung The objective of this study was to evaluate the consumer perceptions towards rubberwood (Hevea brasiliensis) as a premier furniture material. The data for this study were collected from a questionnaire survey completed by 250 buyers who attended the international furniture fairs in Malaysia. Correlation analysis showed that the success factors of rubberwood as a furniture stock in comparison to other furniture wood species are its lower cost, availability, environmental friendliness and easy workability.      

Measuring elastic constants of Hevea brasiliensis using compression and Iosipescu shear test

The increasing demand and widespread utility of wood composite products necessitate the knowledge of the orthotropic engineering and strength properties of the raw wood used for its safe design and effective performance. This research study aimed at finding the orthotropic elastic parameters of a sustainable timber in India, namely rubber wood (Hevea brasiliensis) with respect to the material axes longitudinal (L), radial (R) and tangential (T), which is a potential raw material for laminated products as verified. This study evaluated the three Young’s moduli, the three shear moduli and the six Poisson’s ratios of the wood species, unavailable in literature. Compression test in rectangular prism was used for the determination of the Young’s moduli and Poisson’s ratios. Shear characterization in the three material planes was done using the Iosipescu test. The highest value of normal stiffness of the material in compression was obtained in the longitudinal direction followed by radial stiffness and tangential stiffness. The shear stiffness was largest in the LR plane followed by LT and RT planes. RT plane exhibited the highest Poisson’s ratio and TL plane the lowest. Significant difference was noted in the shear strength of LR planes between block shear test and Iosipescu test but not with the LT planes.     

Minimizing dust emission during routing operation of rubberwood

The study evaluated airborne dust emission (0.1–10 μm) during the routing operation of Rubberwood (Hevea brasiliensis) in the furniture industry in South East Asia. It was found that the average chip thickness of 0.1 mm and wood moisture content of 12–14% minimized dust emission, while the cutting tool rake angle had little influence on dust emission. The study shows that adverse economic implications due to health hazards posed by airborne dust emissions during wood machining can be reduced by manipulating the average chip thickness and work-piece moisture content.     

Drying quality of rubberwood: an industrial perspective

In this study, the kiln drying yield of 30 mm Rubberwood (Hevea brasiliensis) used for the furniture manufacturing industry in South East Asia was evaluated. The results showed that the average yield loss was 10%, and end-checks, splits and warping were the most common drying defects. It was found that sawn timber from older trees (>?21 years) were less prone to drying defects, and the use of stress relieving treatments significantly reduced the incidence of drying defects.     

Investigation of mechanical properties of sandwich panels made of paper honeycomb core and wood composite skins by experimental testing and finite element (FE) modelling methods

In this study, lightweight sandwich panels with different Kraft paper honeycomb core structures and wood composite skins were constructed. The influence of structural parameters, including core shape, cell size, core density, core and web thickness, and material properties of the core and skin layers on the mechanical behavior of these lightweight sandwich panels were studied by experimental testing and finite element modeling methods. The panels were subjected to compression and shear loadings. Test and simulation results indicated that core density and core shape mainly affected the panel stiffness under out-of-plane loading conditions (e.g. E _z , G _xz and G _yz ). Material properties of the skin layer affected the panel stiffness both under in-plane and out-of-plane loadings if the skin layer was orthotropic.