Influence of clay modification on the structure and mechanical properties of EPDM/montmorillonite nanocomposites

Conditions were established for dispersing organic montmorillonite (OMMT) nanolayers into ethylene-propylene-diene rubber (EPDM) matrix in a HAAKE mixer. The experimental results of X-ray diffraction and transmission electron microscopy showed that the MMT modified with trimethyloctadecylamine or dimethylbenzyloctadecylamine existed in the form of an intercalated layer structure and the MMT modified with methlybis(2-hydroxyethyl)cocoalkylamine was fully exfoliated in the EPDM matrix. The expansion of the distance between the silicate layers firstly took place after the HAAKE mixing, then the silicate layers were exfoliated in the EPDM matrix after the EPDM/OMMT composite was cured. The EPDM/OMMT composites had good mechanical properties. The EPDM composite containing 15 phr OMMT which was modified with the alkylamine containing hydroxyl groups showed high tensile strength of 25 MPa. Dynamic mechanical analysis revealed that the glass transition temperature (T-g) of the composites was higher than that of gum EPDM vulcanizate. The OMMTs had delaying effects on the vulcanization reaction and decreased the crosslink density of the EPDM/OMMT composites. (C) 2003 Published by Elsevier Ltd.