Resumen de The effect of wood acetylation on thermal behavior of wood-polystyrene composites
Justo Lisperguer, Cynthia Droguett Castillo, Beatriz Ruf, Mario Nuñez-Decap
Wood-plastic composites are probably one of the most dynamic sectors of today’s plastic industry. Although the technology is not new, there is growing interest in the new design possibilities offered by this marriage of materials. In the world, polystyrene (PS) is the third most utilized thermoplastic after polyethylene (PE) and polypropylene (PP). The uses of PS are different from those of PE and PP because PS’s glass transition temperature (Tg) is approximately 90ºC, and PS is rigid and brittle below this temperature (environmental conditions).One method used to increase PS impact resistance is to include wood fiber, due to a number of potential advantages, as a suitable candidate in fiber-reinforced polymer composites. The principal disadvantage is a poor adhesion between wood and the polymer due to the different chemical structure and polarity. The study’s objective is to investigate the influence of an acetylation reaction on wood flour to reduce wood’s polarity and to improve the affinity and adhesion between polystyrene and wood. Pinus radiata wood flour was acetylated with acetic anhydride, and acetylated wood-polystyrene composites with 20, 40 and 50 % of wood content by weight were prepared. Composites prepared with unmodified wood in the same composition were used to study the influence of the acetylation reaction on thermal behavior of wood-plastic materials. Glass transition temperatures ( Tg ) of acetylated wood-polystyrene composites were compared with pure polystyrene and unmodified wood-polystyrene composites. Dynamic mechanical analysis (DMA ) was utilized to determine Tg and Fourier transform infrared ( FTIR ) was used to study the changes in functional groups during the acetylation process. DMA showed changes in polystyrene’s Tg when mixed with wood. The major effect was the significant increase of 8º C in 50/50 of acetylated wood- polystyrene composites, showing that the use of acetylated wood flour produces wood-plastic composites with better thermal stability than non-acetylated wood
