Mechanical and dynamic mechanical properties of miscible blends of epoxidized natural rubber and poly(ethylene- co-acrylic acid)

Abstract

The mechanical and dynamic mechanical properties of blends of poly(ethylene- co-acrylic acid) (PEA) and epoxidized natural rubber (ENR-50) have been studied after reactive blending in various proportions in a Brabender Plasticorder. The miscibility of the blends has been studied by using a computer simulation method and experimentally confirmed by dynamic mechanical analysis. The dynamic properties of the blends exhibit single glass transition temperature ( T g) values, thus conforming to the law of miscibility. A positive deviation from the Fox equation (theoretical T g) is a clear indication of miscibility via chemical interaction. A new β-transition peak in the blends appeared, and this is assumed to be due to the side-chain ester group vibration, confirming a chemical reaction between the in situ generated OH groups of the ENR and free COOH groups of the PEA. This leads to miscibility between the constituents forming the grafted structure, i.e. PEA- g-ENR. The mechanical properties exhibit a synergism above that calculated via the additivity rule. The chemical interactions have been further confirmed by swelling studies in a common solvent.