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

Abstract

The aims of this work were to determine the color change and physical–mechanical properties of polystyrene glulam from three tropical wood species. Wood laminas were cut from logs harvested from a young plantation forest of manii (Maesopsis eminii), mangium (Acacia mangium), and rubber-wood (Hevea brasiliensis). The laminas were impregnated with monomer styrene that was polymerized using potassium peroxy-disulfate as a catalyst and heat. Three-layer glulam was constructed from the polystyrene laminas, using isocyanate glue and cold press. For comparison purposes, three-layer untreated glulam and solid wood samples were prepared. The results showed that the color change of polystyrene glulam was very small compared with untreated glulam. Polystyrene glulam had the highest density, while the density of untreated glulam did not differ from that of the solid wood. The moisture content of all products was matched to the environment, and fulfilled the Japanese standard. Compared with both types of glulams, solid wood had lower values for modulus of rupture (MOR), modulus of elasticity (MOE), and hardness, but higher shear strength. Meanwhile, polystyrene glulam had lower values for MOR and MOE, equal shear strength and wood failure, and higher hardness than the untreated glulam. All glulams had very little delamination in the hot water test. Only rubber-wood glulams fulfilled JAS 234-2003 for MOR, MOE, shear strength, and delamination. To obtain adequate physical–mechanical properties of glulams, medium-density wood is recommended for glulam manufacturing.

Polystyrene-Impregnated Glulam Resistance to Subterranean Termite Attacks in a Laboratory Test

“…Referring to Hadi et al [ 23 ], after a one-year exposure in the field, four Polish woods with polymer loading between 88 and 135% had a weight loss of 19%, while the untreated woods had 100% weight loss or totally failed. Nevertheless, the polystyrene weight gain of laminae should be considered to a certain degree, along with its optimal mechanical properties, as mentioned by Hadi et al [ 17 ], who noted that the shear strength and rupture modulus of polystyrene glulam were lower than those of solid wood.…”

“…The laminae were placed with a longitudinal fiber orientation along the length of the glulam. Isocyanate glue was applied with a single spread glue line at 280 g/m 2 [ 17 ], and the laminae were then cold-pressed with a specific pressure of 10 kg/cm 2 for 3 h, followed by conditioning at room temperature for two weeks in the laboratory of the Centre for Standardization of Sustainable Forest Management Instruments, Ministry of Environment and Forestry, Bogor, Indonesia.…”

“…In studying the utilization of wood from the plantations mentioned above, some researchers have reported that the small-diameter logs that were made into glued-laminated timber (glulam) were not different from solid wood in terms of physical and mechanical characteristics. Yet, compared to solid wood, the glulam had higher values for the modulus of rupture (MOR), modulus of elasticity (MOE), and hardness, but lower shear strength [ 17 ]. Moreover, impregnated polystyrene wood had increased resistance against subterranean termites [ 18 ].…”

“…Polystyrene glulam had higher density and hardness, but lower moisture content and MOE. In other work, Hadi et al [ 17 ] reported that polystyrene glulams of three fast-growing wood species had lower values for MOR and MOE, equal shear strength and wood failure, and higher hardness than the untreated glulam, and both glulams had slight delamination in the hot water test. In further research, Nurhanifah et al [ 24 ] showed that the shear strength of sengon (Falcataria moluccana) solid wood was not significantly different from polystyrene glulam, meaning the impregnation process of styrene into sengon wood did not affect the gluing process.…”

Strong and Durable Wood Designed by Cell Wall Bulking Combined with Cell Lumen Filling

“…It has good dimensional stability, hardness, strength, and abrasion resistance, making it widely used in the fields of construction, furniture, musical instruments, and industrial equipment [ 7 ]. For instance, previous studies have utilized various monomers, including styrene [ 8 ], methyl methacrylate [ 9 ], n-butyl acrylate [ 10 ], alkoxysilane coupling agents [ 11 ], vinyl monomers [ 12 ], methyl methacrylate (MMA) [ 13 ], and unsaturated polyester resins [ 14 ], to impregnate the wood and polymerize, filling the cell lumina to enhance the strength and dimensional stability of the wood. Research has shown that the composite treatment of wood with functional monomers, such as propylene oxide and methyl methacrylate monomers [ 15 ], ethylene/methyl methacrylate, and styrene/acrylonitrile monomers [ 16 ], can improve the comprehensive performance of wood.…”