Rubber Toughened Polystyrene Composites

A blend was prepared by dissolving a rubber material in styrene and polymerizing the system. The blend contains not only rubber and polystyrene (PS), but also a graft polymer because of the attachment of short polystyrene side chains to the rubber molecules. The toughness of this material was markedly improved compared to that of the unmodified PS. A technology based on bulk polymerization [26] has been widely used the concentrated emulsion polymerization method employed by us, however, allows one to obtain rubber toughened latexes. 

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Rubber-toughened polystyrene composites were obtained similarly by polymerising the dispersed phase of a styrene/SBS solution o/w HIPE [171], or a styrene/MMA/(SBS or butyl methacrylate) o/w HIPE [172], The latter materials were found to be tougher, however, all polymer composites had mechanical properties comparable to bulk materials. Other rubber composite materials have been prepared from PVC and poly(butyl methacrylate) (PBMA) [173], via three routes a) blending partially polymerised o/w HIPEs of vi-nylidene chloride (VDC) and BMA, followed by complete polymerisation b) employing a solution of PBMA in VDC as the dispersed phase, with subsequent polymerisation and c) blending partially polymerised VDC HIPE with BMA monomer, then polymerisation. All materials obtained possessed mixtures of both homopolymers plus some copolymer, and had better mechanical properties than the linear copolymers. The third method was found to produce the best material. 

We have considerable latitude when it comes to choosing the chemical composition of rubber toughened polystyrene. Suitable unsaturated rubbers include styrene-butadiene copolymers, cis 1,4 polybutadiene, and ethylene-propylene-diene copolymers. Acrylonitrile-butadiene-styrene is a more complex type of block copolymer. It is made by swelling polybutadiene with styrene and acrylonitrile, then initiating copolymerization. This typically takes place in an emulsion polymerization process. 

An additional problem arises in attenqiting to predict the moduli of rubber-modified dastics the rubber particles are themselves composite in structure. A typfeal hi inqiact polystyrene (HIPS) m t contain only 6 v(d.% of pcdybutadi-ene, whereas the volume fraction of rubber particles is between 20 and 30%. The additional vcdume comes from sniall sub-inclusions of polystyrene (PS) embedded in the rubber. The problem of relating modulus to structure in rubber-toughened plastics is discussed in a recent review ). 

HIPS polymers consist of a matrix of polystyrene containing approximately spherical particles of rubbery polybutadiene ranging in size from about 0.1 to 10 pm depending on the precise composition and method of polymerisation. The rubber particles may themselves contain small regions of PS as shown in fig. 12.7. Another series of rubber-toughened blends is the acrylonitrile-butadiene-styrene (ABS) terpolymers, which are basically... 

Rubber modifier for impact-resistant plastic Degradative plastics composition resin Zinc salt derivative for toughening polystyrene film... 

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