Elastomer Blends

Abstract

Mixtures are difficult to define within the range of materials employed in the rubber and plastic industries. A composite article such as a tire is a mixture of wire (metal), textile cord (organic fiber), and rubber compounds. The rubber compound itself is a mixture of elastomer, filler, and, usually, extender. Moreover, the elastomer may be a mixture of two or more rubbers. On a smaller scale, the elastomer may contain ‘blocky’ segments or crystalline portions along the polymer chains which act as ‘reinforcing’ agents or stiffeners. These may be similar to the repeat units of the elastomeric part, e.g., isotactic—atactic block copolymers of poly(propylene) or poly(propylene oxide); or different from it, as in the stereo block styrene—butadiene thermoplastic copolymers. Two types of elastomer may of course, be copolymerized or one elastomeric type may be grafted onto another. Furthermore, certain catalysts could cause simultaneous homopolymerization of two monomers. All the foregoing systems are different facets of the broad concept of blends, but some selection is obviously needed. In this review, most emphasis will be placed on elastomer—elastomer blends including their preparation from the constituent elastomers. Reference will be made to elastomer—plastic blends prepared from separate materials and by block/graft type reactions. Blends of one plastic with another lie outside the scope of this review.

Morphology and mechanical and viscoelastic properties of natural rubber and styrene butadiene rubber latex blends

“…Among these blending techniques, latex blending 1-5 has certain advantages. A good degree of dispersion and reinforcement 6,7 occur with latex blending. Another important advantage of latex blending is that the polymer contained in latices and blends can be partially crosslinked in the latex stage without prior coagulation (prevulcanization).…”

Elastomer Blends

“…It is generally found (see, e.g., the conclusions of the recent review article [263] on which this chapter is substantially based) that various authors quote different results from otherwise similar polymers. It has been shown that molecular weight differences have a major effect on blending propensity; thus, it would seem appropriate to suggest that a detailed study of the blending of well-characterized polymers be made, paying attention to micro-and macrostructure, especially of high and low molecular weight "tails" and microgels.…”

Some Fatigue Properties of Rubber Blends

“…The raw rubbers can be blended prior to mixing with other compounding ingredients and to go to an extreme SBR:BR blends could be polymerized to give the range of blend ratios studied. The morphology of the resulting compounds have been studied by several authors [10,11,12,13,14] and others not cited. Currently considerable work is underway with the goal of better understanding the effect of changes in morphology on practical physical performance.…”