Studies on polymer blends. II. Butadiene–styrene copolymers and polybutadiene–polystyrene blends

Abstract

SynopsisThe properties of butadiene-styrene copolymers and of polybutadiene-polystyrene blends were compared. Polybutadiene, polystyrene, and four copolymers having styrene contents of 20,40,60, and 80% were prepared. The copolymers were compared with blends having various styrene contents and prepared by means of latex blending and roll blending. Vulcanizates were prepared by three different curing methods, i.e., sulfur cure, peroxide cure, and radiation cure. The results of the benzene extraction of three vulcanizates showed that the polystyrene blended was not cured by any of the curing methods used. The properties of the vulcanizates of the copolymers were markedly different from those of the blends, i.e., in the case of the blends the properties showed a linear relationship with their blending ratio, while in the copolymers the properties showed a curvilinear relationship which had an inflection point at a styrene content of about 60%. From this phenomenon of the copolymers, it was proposed that the second-order transition point of styrene is the cause of the properties showing this peculiar point. From the results, it was found that the behavior of styrene in copolymers is essentially different from that in blends. INTRODUCTIONRecently the consumption of butadiene-styrene rubber has increased rapidly, and in the rubber industry it has become an indispensable rubber.It is well known that in butadiene-styrene rubber the properties of the copolymer are affected by the bonded styrene content. As the quantity of bonded styrene is increased, the copolymer becomes less rubbery and more leatherlike and resinlike. Many studies concerning the processing method and the properties of the copolymers have been reported for copolymers having a commercially practical bonded styrene content, ie., SBR and high-styrene resin. However, copolymers containing styrene in amounts outside of the current practical range have not been studied extensively.There are a few studies on the relationship between the bonded styrene content and the properties of the A study on the methods of blending natural rubber with butadienestyrene rubber has been r e p~r t e d .~In order to clarify the difference between the properties of copolymers and of blends of the butadiene and styrene, copolymers having various styrene contents and physically blended mixtures of polybutadiene (rubber) with polystyrene (resin) having styrene contents corresponding to those of the copolymers were studied.The butadiene-styrene copolymers used were prepared on a pilot-plant scale for this study and had molecular weights of about 200,000. The blends were prepared by means of latex blending and roll blending. To study the differences in properties of the vulcanizates, both the copolymers and the blends were cured with sulfur, with peroxide, or by radiation.Results of benzene extractions of these vulcaniaates showed that the polystyrene blended was not cured by any of the curing systems.Results on the vulcanizates indicate that the properties of the blends, showed a lin...

Elastomer Blends

“…In order to clarify the difference between copolymers and blends, Shundo et al [176] have studied a series of butadiene-styrene copolymers and polybutadiene/polystyrene blends of identical styrene contents. In order to clarify the difference between copolymers and blends, Shundo et al [176] have studied a series of butadiene-styrene copolymers and polybutadiene/polystyrene blends of identical styrene contents.…”

Studies on polymer blends. III. Butadiene–acrylonitrile copolymer and polybutadiene–polyacrylonitrile blend

“…I n the cases of butadienestyrene polymer systems, studies of the blending method and of the comparison of the properties of copolymers and blends have been presented by the authors. [2][3] I n this study, the properties of butadiene-acrylonitrile copolymers were compared with those of polybutadiene-polyacrylonitrile blends and other blends. I n the butadieneacrylonitrile copolymer composition, it was difficult to obtain homogeneous copolymers having acrylonitrile unit contents of more than 5040% because of the monomer reactivity ratio.…”