Asymmetric microcellular composites: Mechanical properties and modulus prediction

Abstract

In the first part of this study, asymmetric microcellular composites were prepared by injection molding to study their morphological properties as a function of temperature gradient inside the mold (0–60℃), as well as foaming agent (0–1%) and natural fiber (0–30%) contents. High-density polyethylene, flax fiber, and azodicarbonamide were used for the matrix, reinforcement, and chemical blowing agent, respectively. From the samples produced, mechanical properties (tensile, flexion, torsion, impact) are analyzed in this second part. Mechanical properties were found to be strongly influenced by density reduction and natural fiber content. It was also found that fiber addition provides higher reinforcement in flexion than torsion and tension. Also, flexural modulus and impact strength were relatively unaffected by foaming agent content for the range of parameters studied. From the experimental data obtained, a simple mechanical model based on density profile is presented to predict the elastic moduli of asymmetric structural composite foams.