Dynamic mechanical analysis of tropical wood–polymer composites

Abstract

AbstractWood–polymer composites (WPC) of Geronggang (GE; Cratoxylon arborescens), a light tropical hardwood, impregnated with methyl methacrylate (MMA) and styrene‐co‐acrylonitrile (3 : 2; STAN), were prepared by in situ polymerization using γ radiation or catalystheat treatment. The dynamic flexural storage modulus, E′, for oven‐dried GE, moist GE, and GE–MMA and GE–STAN composites decreased with increasing temperature. The percentage decreases for GE with 10 and 16.5% moisture contents were 74.5 and 98.2%, respectively, which were higher than those for GE and GE composites, which ranged between 40 and 50%. The impregnated polymers were not as effective as water in acting as plasticizers, due to their nonpolar nature and much higher molecular weights. The α‐transition peaks for moist GE and GE composites were more distinct and were shifted to lower temperatures than those for oven‐dried GE. The values ranged between 75 and 150°C for moist GE and between 102 and 170°C for the GE composites. The α‐transitions of the catalyst–heat‐treated GE composites were lower than that of the radiation‐induced counterparts. GE–STAN composites were also observed to have lower α‐transition temperatures than those for GE–MMA for the respective treatment process, which seems to suggest that STAN interacted to a greater extent with cell wall components than did MMA.