Moisture absorption effects on the thermal and mechanical properties of wood flour/linseed oil resin composites

Abstract

The thermal and mechanical behavior of new natural polymeric composite materials after exposure to humid environments must be well known and understood in order to predict their performance in final applications. For this reason, composites made from unsaturated polyesters based on linseed oil and filled with wood flour were exposed to environments of different relative humidities and their final properties were measured. In general, the equilibrium moisture content increased as the wood flour percentage increased. Dynamic mechanical tests performed in temperature scan mode were carried out in order to monitor the changes resulting from moisture absorption on the main transition temperature of the matrix (Tα). The temperature of this transition decreased as the amount of absorbed water increased, but the effect was partially reversible by re-drying the samples. The mechanical properties were also strongly affected by moisture. The flexural modulus and ultimate stress of the composites decreased after equilibration in humid environments. © 2006 Society of Chemical Industry.