Performance of compreg laminated bamboo/wood hybrid using phenolic-resin-treated strips as core layer

Physical and mechanical properties of compreg laminated bamboo/wood hybrid using phenolic-resin-treated strips as core layer were investigated. Compreg laminates made from treated core layer revealed better properties than the untreated control samples. Compreg laminated wood showed lower properties compared to compreg laminated bamboo and bamboo/wood hybrid. Assembly orientation exerted great influence on the properties as parallel laminated samples showed better strength and dimensional stability

Oil-heat treatment of rubberwood for optimum changes in chemical constituents and decay resistance

Effects of oil—heat treatment on chemical constituents and decay resistance of rubberwood (Hevea brasiliensis) were investigated in this work. Oil—heat treatment palm oil as heating medium was carried out by immersing rubberwood samples (300 mm longitudinally × 20 mm radially × 20 mm tangentially) in hot oil bath. Wood samples were immersed in the palm oil at temperatures and time periods ranging from 172 to 228 °C and 95 to 265 min respectively. Cellulose, hemicellulose and lignin contents and weight loss of samples by the fungus Pycnoporus sanguineus were evaluated. Four linear and one quadratic models were developed using response surface methodology. High adjusted r² values were obtained and the adequacy of the models was confirmed. Cellulose and hemicellulose reduced in treated samples. Such reductions became greater with increasing temperature and exposure time. However, lignin content of samples increased with increasing temperature of treatment and extended time. Decay resistance of treated samples against P. sanguineus improved with increased treatment temperature and time. The enhancement in decay resistance was highly related to chemical constituents in the treated sample

Resistance of Laminated Veneer Lumber (LVL) produced from rubberwood, radiata pine and larch against subterranean termites and white rot fungi

Laminated veneer lumbers (LVLs) were fabricated using rubber wood, radiate pine and larch wood. Solid rubber wood was used to serve as control for comparison purpose. All of the wood samples were exposed to subterranean termites and white rot fungi for durability evaluation. The results showed that rubber wood LVL had the highest resistance against both deterioration agents in comparison to control, confirming that the resistance of non-durable wood species could be improved by converting them into LVL

Iskorištavanje borovine (Pinus sylvestris L.) s greškama za proizvodnju kompozitnog drva

This study presents opportunities for the utilization of timber by-products with defects for manufacturing engineered wood panels. Three gluing methods were proposed for this waste raw material derived from Scots pine (Pinus sylvestris L.) wood. The methods used for combining and gluing enabled a more complete and complex utilization of wood with defects. The physical properties (density and moisture content) and mechanical properties (bending strength and modulus of elasticity) of the laboratory-fabricated engineered wood panels were evaluated in accordance with the European standards. The highest density of 643 kg/m3 and bending strength values (28.6 N/mm2) were obtained from the panels manufactured using method 3 and veneered with beech veneer sheets. The modulus of elasticity of the laboratory-made engineered wood panels reached values of up to 5580 N/mm2. This study demonstrated the feasibility of the utilization of defective wood pieces in the manufacturing of engineered wood panels.U radu je predstavljena mogućnost iskorištavanja otpadnog drva s greškama za proizvodnju kompozitnog drva u graditeljstvu. Predložene su tri metode lijepljenja otpadnog drva borovine (Pinus sylvestris L.). Metode kombiniranja i lijepljenja omogućile su potpunije iskorištavanje drva s greškama. Fizička svojstva (gustoća i sadržaj vode) i mehanička svojstva (čvrstoća na savijanje i modul elastičnosti) laboratorijski proizvedenih kompozitnih drvnih ploča za graditeljstvo ocijenjena su prema europskim standardima. Najveću gustoću (643 kg/m3) i čvrstoću na savijanje (28,6 N/mm2) imale su ploče proizvedene metodom 3 i furnirane bukovim furnirom. Modul elastičnosti laboratorijski proizvedenih kompozitnih drvnih ploča za graditeljstvo dosegnuo je vrijednost od 5580 N/mm2. Ovo je istraživanje uputilo na mogućnost iskorištavanja drva s greškama za proizvodnju kompozitnih drvnih ploča namijenjenih graditeljstvu

Effects of pressing cycles and durations on the properties of compreg oil palm wood

Oil palm wood (OPW) extracted from the oil palm trunks and subjected to a four-step compreg method consisted of drying, impregnation, re-drying and hot-pressing densification process. For the densification process, four different pressing cycles (involving 1–3 cycles) were proposed and conducted with three pressing durations (30, 35 and 40 min). Properties of the compreg OPW were evaluated. The results revealed that the samples compressed using the pressing process with more than 1 cycle displayed significantly better water absorption and thickness swelling. OPW samples that compressed with longer pressing durations also reported better performance and the formaldehyde emission decreased along with extending pressing durations. However, the improvement was not statistically significant, therefore, 30 min pressing duration is sufficient to achieve satisfied properties

Reducing formaldehyde emission of urea formaldehyde-bonded particleboard by addition of amines as formaldehyde scavenger

Particleboard is one of the building materials that contribute to the emittance of formaldehyde in enclosed area. In order to reduce the formaldehyde emission from particleboard, amines were added into the urea formaldehyde (UF) resin as formaldehyde scavenger. The amines used were methylamine, ethylamine and propylamine. 0.5, 0.7 and 1% of each type of amine were added into UF resin and the mixtures were used to produce particleboard from rubberwood particles. The properties of the UF resin after addition of amines such as gelation time, viscosity, pH, free formaldehyde content and thermal stability were evaluated. The physical, mechanical properties and formaldehyde emission of the produced boards were also assessed. The results revealed that fully cured amine-containing UF resin possesses higher thermal stability compared to control UF resin. Amine-containing UF resin also had longer gelation time due to higher pH value. Nevertheless, both physical and mechanical properties of the resultant particleboard were negatively affected. Particleboard made from amine-containing UF resin had higher thickness swelling and water absorption. In addition, lower bending strength and internal bonding strength were also recorded. Insufficient pressing time for fully cured of resin might be the reason for such phenomenon. Particleboard with F*** emission level (0.5 ≤ x ≤ 1.5 mg/L) as specified in Japanese Industrial Standard (JIS) or European's E0 class equivalent were achieved when ethylamine and propylamine were added, regardless of dosage used. This study showed the feasibility of using amines as formaldehyde scavenger. However, optimisation of processing parameters is needed to enhance the physico-mechanical properties of the particleboard

Addition of ammonium hydroxide as formaldehyde scavenger for sesenduk (Endospermum diadenum) wood compregnated using phenolic resins

Compregnated sesenduk (Endospermum diadenum) was produced using low and medium molecular weight phenol formaldehyde resin. 0, 1, 1.5 and 3 % of aqueous ammonium hydroxide (NH3·H2O) were incorporated into the resin to act as formaldehyde scavenger. A maximum of 85.7 % reduction in formaldehyde emission was recorded, but the mechanical and physical properties of the treated sesenduk wood were negatively affected by the ammonium hydroxide addition

Life table of Cochlochila bullita stål (hemiptera: tingidae) on Orthosiphon aristatus (blume) miq. and Ocimum basilicum l. in laboratory conditions

Ocimum tingid, Cochlochila bullita Stål (Hemiptera: Tingidae) is a pest of Lamiaceae plants such as basil, tulsi and coleus. It is now being recorded in Malaysia as a pest of the cat’s whiskers plant, Orthosiphon aristatus (Blume) Miq. Nevertheless, apart from its brief biological description, no other information is available. The life table of this pest was studied in laboratory conditions. Development time for C. bullita feeding on O. aristatus was 23.3 ± 0.9 days, which was found to be similar to those feeding on Ocimum basilicum (22.8 ± 0.3 days). Although C. bullita posts a higher mortality rate on O. aristatus than on O.basilicum (52% vs. 37%), the adult longevity of the bugs that feed on O. aristatus (♀: 33.9; ♂: 38.2 days) was found to be significantly higher than those bugs that feed on O.basilicum (♀: 27.2; ♂: 26.0 days). The pre-ovipostion, ovispostion and fecundity of C. bullita were also different between the host plants. The net reproductive rates (R0), finite rate of increase (λ) and intrinsic rate of increase (r) were also higher on O. aristatus (10.7504, 1.0690 and 0.0667), although there was an increased in immature survival on O. basilicum (6.0287, 1.0556 and 0.0541). Therefore, it is concluded that O. aristatus is as good as O. basilicum, or the population growth of C. bullita is more favoured as compared to O. basilicum