Grafting efficiency Ethylene oxide

Improved ABS-similar resins can be obtained by grafting SAN onto ethylene-propylene-diene terpolymers (EPDMs) which contain, usually, a much lower degree of unsaturation than polybutadiene, thus achieving hi er thermal-oxidative resis-tance However, only EPDMs containing a sufficient amount (7—10 double bonds per 1,000 C atons) of reactive unsaturations, e.g. ethylidene or isopropylidene groups, display a grafting efficiency sufiident to bring about compatibility of the ssy i se with the rubbery one and hence satisfactory final properties. 

Table 3 shows that in the copolymerization of macromer with ethylene oxide different types of catalyst attained different grafting efficiencies, which was calculated by the following equation ... 

An alternative (and perhaps more efficient) polymeric surfactant is the am-phipathic graft copolymer consisting of a polymeric backbone B (polystyrene or poly(methyl methacrylate)) and several A chains ( teeth ) such as poly(ethylene oxide). The graft copolymer is referred to as a comb stabiliser - the polymer forms a brush at the solid/liquid interface. The copolymer is usually prepared by grafting a macromonomer such as methoxy poly(ethylene oxide) methacrylate with poly(methyl methacrylate). In most cases, some poly(methacrylic acid) is incorporated with the poly(methyl methacrylate) backbone - this leads to reduction of the glass transition of the backbone, making the chain more flexible for adsorption at the solid/liquid interface. Typical commercially available graft copolymers are Atlox 4913 and Hypermer CG-6 supplied by ICI. 

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