Expanded wood fiber polystyrene composites: processing-structure-mechanical properties relationships

In this study, processing-structure-mechanical properties relationships in expanded wood fiber polystyrene composites (EPSC) made with a physical blowing agent were investigated. A systematic investigation was performed based on a statistical experimental design. The samples were saturated with carbon dioxide at high pressure and ambient temperature and the saturated specimens were expanded at elevated temperatures. The relations between impact and tensile properties of EPSC and foaming process and structure were studied. Fiber content was found to be the most important parameter controlling impact strength and tensile modulus. The impact strength of EPSC was increased about three times when the fiber content increased to 20%. Using the Halpin-Tsai equation, a model was developed to relate tensile modulus to the density of EPSC.