Publisher Summary
This chapter discusses various aspects of elastomer blends. Blending or mixing of elastomers is undertaken for three main reasons: improvement of the technical properties of the original elastomer, achievement of better processing behavior, and lowering of compound cost. All elastomers have deficiencies in one or more properties and blending is a way of obtaining optimum all-round performance. Elastomer blends are one class of composite materials used in polymer-based industrial products. They are macro scale mixes of high molecular weight elastomer phases. On a microstructural scale, the elastomer could contain blocky or crystalline chain segments which act as reinforcing agents or stiffeners. These may be similar to the repeating units of the elastomeric part.

12 – Elastomer Blends

Chapter 12 – Elastomer Blends

The effect of heat treatment in the so-called phase inversion region was studied using uncured mill blends of various commercial styrene—butadiene copolymer rubbers (styrene content, 23.5 to 48 wt-%; styrene block, 0 to 18 wt-%) with general-purpose polystyrene resin (blend ratio, 80–40: 20–60, in wt-%). It was found that the effect of heat treatment on the hardening or softening phenomenon of blends is different in the random type from that in the block-type styrene—butadiene copolymer rubber. A thorough discussion led us to conclude that this difference is caused by the strong interaction between the polystyrene block of the copolymer and the styrene homopolymer of general-purpose polystyrene resin.

Changes in mixing states of styrene–butadiene copolymer rubber and general‐purpose polystyrene resin mill blend by heat treatment

The softening phenomenon by remilling of uncured blends of various commercia styrene—butadiene copolymer rubber (styrene content, 235 to 48 wt-%, styrene block 0 to 18 wt-%) with general-purpose polystyrene resin was mainly studied by examining the blend ratio dependence of hardness and compression modulus (in logarithmic form), with special attention to the state of dispersion of the polymers It was found that the blend of styrene—butadiene copolymer rubber with general-purpose polystyrene resin forms a microheterogeneous polymer blend system and that the hardness and the compression modulus change in S-shaped curves versus blend ratio However, the degree of softening phenomenon by remilling (roll surface temperature, 70°–90°C) was found to be different for the two blend systems, ie, random styrene—butadiene copolymer rubber and block styrene—butadiene copolymer rubber The softening phenomenon is more pronounced in random-type rubbers; and in some block-type rubbers, no softening phenomenon was observed The influence of the styrene content of the polymer is small Further discussions have shown us that the strong interaction between the polystyrene block of the copolymer and the styrene homopolymer of the general-purpose polystyrene resin controls the state of dispersion of polymers thereby causing this difference in the softening phenomena among the different kinds of styrene—butadiene copolymer rubbers

K. Satake

Papers

Changes in mixing states of styrene–butadiene copolymer rubber and general‐purpose polystyrene resin mill blend by heat treatment

Softening phenomenon by remilling of styrene–butadiene copolymer rubber–general-purpose polystyrene resin blend