Effect of nodule shape for modeling of auxetic microporous polymers

Abstract

Previous models for describing auxetic microporous polymers adopt 2D rectangular blocks with fibril interconnections. In this paper, spherical nodes are used in order to approximate the granular nodule shape and for taking into consideration the 3D nature of the nodes. Assuming curvilinear motion of the nodes as a result of fibril rotation, a quantitative description of the Poisson’s ratio is given as a function of the nodule density packing factor. Comparison with the 3D rectangular model shows that the spherical model gives a more conservative description of the Poisson’s ratio although both models exhibit similar trend. Results reveal the significance of the assumed node shape for modeling the Poisson’s ratio of auxetic microporous polymers.