Investigation of the temperature-dependent mechanical behavior of a polypropylene-pine composite

Wood-plastic composites have been recognized as versatile and practical materials for use in many light-structural uses. Recently, more structurally demanding applications have surfaced, which require an improved understanding of mechanical performance and design methodologies. Research addressing the influence of service temperature on mechanical performance with the goal of assigning structural design values is lacking. This study examines the effect of temperature on the mechanical performance of a polypropylene-pine composite formulation. Static tests were performed at temperatures between 21.1 and 80.0°C to determine the material constitutive relations and ultimate properties in tension and compression. A statistical approach was proposed to assess design thermal loads according to geographical location. Both Young's modulus and ultimate stress were found to decrease with temperature while maximum strain increased linearly with temperature. Temperature adjustment factors were developed over the range studied and were found to decrease properties by as much as 50% at the highest service temperatures. A simple thermal load methodology based on an ASHRAE standard was proposed for determining prevailing thermal conditions in design.