AFM Studies on Silica Dispersion in EPDM Rubber

Abstract

EPDM rubber formulations filled with precipitated silica and cross-linked by peroxide vulcanization have been investigated with the objective of realizing better processing characteristics and vulcanizate properties. Dispersion of silica in EPDM rubber in the presence of conventional coupling agents and in the presence of an epoxy resin has been investigated using atomic force microscopy (AFM) and scanning electron microscopy (SEM). AFM results of EPDM rubber compounds containing silica fillers in the presence of the epoxy resin have exhibited improved silica dispersion in terms of scanned height. The latter has been found to be in the range of 0–100 nm for EPDM rubber—silica systems with epoxy resin, while in the absence of the resin, scanned height has been found to be in the range of 0–700 nm. The significant reduction in scanned height in the presence of epoxy resin has been attributed to the reduction in surface roughness which is an indication for good dispersion of silica in the rubber. Morphological studies using SEM, mechanical properties, and Mooney-Rivlin constants all have shown significant improvement in performance properties of EPDM rubber—silica compounds containing epoxy resin and vulcanized with dicumyl peroxide.

Morphology of Silica-Reinforced Natural Rubber: The Effect of Silane Coupling Agent

“…Natchimuthu has investigated the effect of an epoxy resin on the dispersion characteristics of silica fillers in EPDM rubber using AFM. 5 Improved silica dispersion for EPDM-silica systems with epoxy resin was reported in terms of scanned height in the range of 0-100nm, as compared to the scanned height of a compound without resin which was found to be in the range of 0-700nm. Jeon et al have successfully distinguished two different polymer domains in an unfilled rubber blend (natural /synthetic rubbers) using tapping mode AFM.…”

Dispersion and vulcanization characteristics of nitrile rubber reinforced with N,N‐dimethylacetamide/lithium chloride treated silica

“…This drop could be directly attributed to TESPT as a coupling agent in reducing the aggregate size of silica due to enhanced interactions between silica and rubber thus providing a strong interface between them. 37 When DMAc/LiCl treated silica is used without TESPT, maximum height and average roughness values, 117 and 193 nm with corresponding Ra values at 8 and 47 nm are observed for rubber with high and medium nitrile rubber, respectively. The micrographs 6c and 7c are similar to that of the samples containing TESPT alone.…”

Analytical method development to predict the in-rubber dispersibility of silica

“…2.24). However, unvulcanised rubber can only be investigated in contactless mode due to the fact that raw compounds are, in general, too sticky and soft for fine tactile measurements [95]. [95] Light Optical Dispersion Measurement Methods The light optical dispersion measurement methods can be divided basically into two categories, namely the reflection and transmission method.…”

“…However, unvulcanised rubber can only be investigated in contactless mode due to the fact that raw compounds are, in general, too sticky and soft for fine tactile measurements [95]. [95] Light Optical Dispersion Measurement Methods The light optical dispersion measurement methods can be divided basically into two categories, namely the reflection and transmission method. The most common reflection methods are ASTM D 2663 method A, PHILLIPS, Dispergrader/-tester, the Dispersion Index Analysis System (DIAS) and the recently developed confocal laser microscope (CLM), whereas the typical transmission method is the CABOT TL (ASTM 2663 method B).…”