Molecular model for HNBR with tunable cross-link density

Abstract

We introduce a chemically-inspired, all-atom model of HNBR and assess its perfor- mance by computing the mass density and glass transition temperature as a function of cross-link density in the structure. Our HNBR structures are created by a procedure that mimics the real process used to produce HNBR, i.e., saturation of the carbon- carbon double bonds in NBR, either by hydrogenation or by cross-linking. The atomic interactions are described by the all-atom “Optimized Potentials for Liquid Simula- tions" (OPLS-AA). In this paper we: first assess the use of OPLS-AA in our models, especially using NBR bulk properties, and second evaluate the validity of the proposed model for HNBR by investigating mass density and glass transition as a function of the tunable cross-link density. Experimental densities are reproduced within 3% for both elastomers, and qualitatively correct trends in the glass transition temperature as a function of the monomer composition and cross-link density are obtained.