Abstract
A method has been developed for determining the amount of ungrafted rubber in ABS polymers. First the styrene-acrylonitrile (SAN) resin is removed by extraction with ethyl acetate. The composition of the SAN resin was determined by NMR analysis. The ethyl acetate insoluble material which consists of graft polymer and ungrafted rubber is then extracted with a mixture of hexachlorobutadiene and ethyl acetate The ungrafted rubber dissolves in the extraction solvent mixture while the graft polymer remains insoluble Filtration, concentration of the filtrate by vacuum distillation and NMR analysis of the concentrated filtrate using an internal standard technique provided the amount and composition of the ungrafted rubber. The data also permitted the amount and composition of the graft polymer to be calculated.
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