Influence of the clay modification and compatibilizer on the structure and mechanical properties of ethylene-propylene-diene rubber/montmorillonite composites

Ethylene-propylene-diene rubber (EPDM)/montmorillonite (MMT) composites were prepared through a melt process, and three kinds of surfactants with different ammonium cations were used to modify MMT and affect the morphology of the composites. The morphology of the composites depended on the alkyl ammonium salt length, that is, the hydrophobicity of the organic surfactants. Organophilic montmorillonite (OMMT), modified by octadecyltrimethyl ammonium salt and distearyldimethyl ammonium salt, was intercalated and partially exfoliated in the EPDM matrix, whereas OMMT modified by hexadecyltrimethyl ammonium chloride exhibited a morphology in which OMMT existed as a common filler. Ethylene-propylenediene rubber grafted with maleic anhydride (MAH-g-EPDM) was used as a compatibilizer and greatly affected the dispersion of OMMT. When OMMTs were modified by octadecyltrimethyl ammonium chloride and distearydimethyl ammonium chloride, the EPDM/OMMT/MAH-g-EPDM composites (100/15/5) had an exfoliated structure, and they showed good mechanical properties and high dynamic moduli. (C) 2004 Wiley Periodicals, Inc.