Multiphase polymer processing: Controlled‐ingredient‐distribution mixing and its effect on some properties of styrene‐butadiene (SBR)/butadiene‐acrylonitrile copolymer rubber blend compounds

Abstract

The flex‐crack‐growth resistance and oil‐swelling resistance of a styrene‐butadiene (SBR)/butadiene‐acrylonitrile co‐polymer (NBR) rubber blend are studied as a function of the distribution of ingredients in the individual rubber phases. The blends consist of 70:30 weight ratio of SBR:NBR with incorporation of 82.5 phr carbon black and other ingredients via the controlled‐ingredient‐distribution mixing procedure. The results show that flex crack growth is affected by the distribution of carbon black. Better flex crack growth resistance could be achieved by adding 10 percent of carbon black to the NBR rubber phase and 90 percent to the SBR phase. The swelling of these rubber blends in ASTM #2 oil is also affected by the location of carbon black and by the mixing history. The blends with more black initially preloaded in the SBR phase have lower swelling, as have blends with shorter cross‐mixing time or the mill. A simple equation based on the permeation/moduli of composite materials is proposed to describe the swelling of this rubber blend in terms of the swelling of the constituent rubber phases, the distribution of ingredient in the individual rubber phases, and the blend morphology. One of the key assumptions is to consider the individual black preloaded rubber as a continuum. The quantitative correlation with the observed swelling data is reasonably good.

Dynamic properties of star‐shaped, solution‐polymerized styrene–butadiene rubber and its cocoagulated rubber‐filled with silica/carbon black

“…In other literature, there have been few reports on crack generation and development rate; most reports have been on fatigue life. Compared with Lee's investigation, the N4 nanocomposite shown in Figure (b) showed more than twice the cycles with only half the CB content. Han and Han reported that it needed 0.5–1.5 × 10 4 cycles to reach a 3‐mm fatigue crack, but the N series of nanocomposites exhibited 8–27 × 10 4 cycles in this study.…”

High Performance Oil Resistant Rubber

“…From previous studies [16][17][18][19], it was found that, the oil immersion of rubber/PVC blend compounds, the oil molecules must penetrate in the rubber phase and go around the PVC phase. This is schematically illustrated in Figure 2.…”