Structure and properties of rubbertoughened polyethylene-based blends

Abstract

Abstract The preparation, thermal behaviour, mechanical properties and morphology of a family of binary blends composed of components each containing ionic functionalities are examined. One component is a semicrystalline copolymer, metal-neutralized ethylene-methacrylate (M-EMA), and the other an elastomeric component, metal-neutralized sulphonated ethylene-propylene diene copolymer (M-SEPDM). These polymeric materials contain low levels of ionic groups (≤ 10 mol%) which are capable of coulombically associating together into microphase-separated regions. These regions contain nonstoichiometric levels of ionic groups. A general characteristic of these blend systems is that the mechanical properties and morphology are directly influenced by the specific composition ratio of rubber to semicrystalline component. Without the associating units on one (or both) of the components, the resulting blends have grossly phase-separated components. The interfacial adhesion is weak, as indicated by poor tensile properties. The inter-relationship between structure and mechanical properties is discussed in terms of changes in the initial spherulitic morphology of the M-EMA component with the addition of increasing levels of the coulombically associating elastomeric component, M-SEPDM.