Comprehensive analysis of mechanical properties of microcellular polypropylene: Experiment and simulation

Abstract

A series of microcellular polypropylene (PP) with different bubble size and expansion ratio were prepared by supercritical CO2 moulding compression foaming, and their compressive, flexural and tensile properties were measured. A comprehensive calculation model for the mechanical properties of polymer foam based on tetradecahedron structure was further established, and the error between the simulation results and the experimental results is less than 25%. Based on the model, the contributions of the elastic stress of polymer matrix and counter-acting force of gas to the elastic modulus were quantitatively analyzed for the first time. The results show that the smaller bubble size can improve the compressive elastic modulus and flexural elastic modulus but has little effect on the tensile elastic modulus. At the same time, the counter-acting force of gas has a positive effect on the compressive elastic modulus, but has a weakening effect on the tensile elastic modulus, and has almost no effect on the flexural elastic modulus. Finally, the generality of the above model is verified by the prediction for elastic modulus of different polymer foams.