Physical and Mechanical Properties of Three Polystyrene Impregnated Indonesian Wood Species

Abstract

Wood has long been recognized by the community, as the multi-purpose materials. In this regard, wood materials can be utilized for either construction, decoration, source of ~nergy, weapons, or other uses. Wood, as multi-purpose materials and considering its ~ssential existence, in its development has underwent a lot of modification. This fact is also spurred by some accompanying inconvenient situations, e.g. more difficulty in procuring wood, the· ever-increasing price of solid wood products, and less available timber with adequate strength and high durability; and even by the demand of creating appropriate technology applicable to a more efficient wood utilization (Hadjib and Abdurachman, 1999).Since then, certain people or related parties have made a great stride in adopting proper technologies to convert wood such that its properties can be suited with the needs of the people/ parties referred to. Among them is the technology of manufacturing wood polymer composite (WPC) so-called more famously as wood plastic. Wood plastic has some benefits, among which are its rigidity and high strength, thereby rendering it suitable for its heavy-duty uses under harsh circumstances. Besides, this plastic technology can also transform wood of rather soft/weak texture as well as low durability into a hard, rigid, durable, dimensionally more stable, and stronger material (Had jib and Sumarni, 2000). I. INTRODUCTIONThe disadvantage of fast-growing species is that they have inferior physical and mechanical properties. Polystyrene impregnation can be applied to improve physical and mechanical properties. Wood samples, which were dried until 10% moisture content were put into impregnating tank and vacuum pressured at 20-mm Hg for two hours. During the gradual release of vacuum, styrene monomers, vinyl acetate monomers and terbutyl-peroxide catalyst was streamed into the tank. Afterwards, the pressure inside the tank was allowed to decrease to 500 mm Hg and kept for 60 minutes. Wood samples which had been impregnated were subsequently immersed in water, then wrapped in aluminum foils and put in the oven for 24 hours at 60°C. The samples were then tested for the polymer loading and their physical and mechanical properties. The results showed that the polymer loadings in wood plastics with the species of origin (i.e. consecutively sengon, pine and rubber wood) were 118%, 72% and 44%, respectively. Impregnation with polystyrene (copolymer of styrene and vinyl acetate monomers) could improve the physical and mechanical properties of wood plastics, i.e. specific gravity, moisture content, water absorption, shrinkage/ swelling, compression parallel to the wood grain, MOR and MOE. Greater use of vinyl acetate decreased physical and mechanical properties.Keywords: wood species, vinyl acetate, styrene monomers, polystyrene copolymer, wood plastic ABSTRACT Nurwati Hadjib1

Color Change and Physical-Mechanical Properties of Polystyrene-Impregnated Glulam from Three Tropical Fast-Growing Wood Species

“…The higher density wood had smaller voids that could be filled by the polystyrene. This result was in line with the findings of other researchers who reported that wood with a higher density had a lower weight percent gain of polystyrene polymer loading [9].…”

“…Budiman et al [11] impregnated polystyrene into manii wood with the density of 370 kg/m 3 and obtained a polymer loading of 6.2%, which was 63% lower than our result. In contrast, Hadjib [9] used rubber-wood with a density of 510 kg/m 3 and got polymer loading of 26.9%, or more than twice our result. As shown in Table 1, wood species had a highly significant effect on weight percent gain due to polystyrene impregnation.…”

“…According to Pelit and Emiroglu [8], the polystyrene-impregnated fir (Abies bornmuelleriana) and aspen (Populus tremula) wood had higher MOR values than untreated wood. Other studies indicated that polystyrene manii and rubber-wood had higher MOR values than solid wood [9,11]. Table 6 shows that polystyrene glulam had a 17.4% lower MOR compared with untreated glulam, despite polystyrene lamina having a higher MOR than untreated lamina.…”

“…Afterward, a pressure of 9.81 bars was applied for another 30 min. After the impregnation process, each lamina was wrapped with aluminum foil (to prevent the polystyrene solution to come out during the polymerization process; this did not make the apparatus dirty), and placed in an oven at 60 • C for 24 h [9,11]. The foil was then removed, and each lamina specimen was weighed to calculate the weight percent gain (WPG).…”

“…Some research on tropical woods has shown that polystyrene impregnation of pine (P. merkusii), rubber-wood (Hevea brasiliensis), and sengon increased MOR, MOE, and hardness [9]. Polystyrene impregnation of randu (Ceiba pentandra) and angsana (Pterocarpus indicus) wood enhanced the density, dimensional stability, hardness, MOE, MOR, and compression parallel to the grain [10].…”