Young's moduli prediction of polypropylene foams using finite element method

Based on periodic tetrakaidecahedra two finite element models are proposed in this paper to predict the Young's moduli of grafted closed-cell polypropylene (PP) foams with or without short-fiber reinforcement. The predicted Young's modulus of the PP foam without short-fiber reinforcement compares well with the empirical equations proposed by Gibson and Ashby. The predicted Young's moduli of the PP foams with short-glass-fiber or short-carbon-fiber reinforcement compare fairly with the modified Lewis-Nielson equation that is first proposed in this paper. The proposed finite element models prove to be acceptable to predict the Young's moduli of the grafted closed-cell PP foams with or without short-fiber reinforcement. However, further experimental and theoretical investigations are needed to justify the modified Lewis-Nielson equation for the short-fiber reinforced PP foams with different fiber type, different fiber volume fraction, different fiber packing condition, and/or wider range of fiber aspect ratio.