Healing phenomenon adapted to understand the miscibility of polymer blends: An approach based on the deformation mechanism

Abstract

Following many years of studies on polyethylene blends, several indirect classical experimental methods (DSC, XRD, DMA, cryogen fracture surface using SEM, and Rheological Test in Oscillatory Flow) have been used to evaluate the compatibility between polyethylene blends. Here a study of a high-density polyethylene (HDPE)—ultrahigh molecular weight polyethylene (UHMWPE) system, which evidences that the compatibility of mixtures using these experimental methods does not assure good mechanical performance of the blends. In addition, the potential that these blends can perform mechanically may be overestimated. Based on the theory of healing at a polymer-polymer interface, it was shown that the maximum mechanical performance of the HDPE-UHMWPE blend can be obtained for long time molecular diffusion when the mixtures equilibrium (maximum mixing degree) at the HDPE-UHMWPE interphase is achieved. The degree of mixture at the HDPE-UHMWPE interphase was assessed indirectly by the deformation mechanism that each phase and the interphase plays during the tensile test (at solid state). The advances reported in this paper can contribute to understanding the mechanical performance of different systems formed by compatible polyethylene blends.