Prediction of the creep of heterogeneous polymer blends: rubber-toughened polypropylene/poly(styrene-co-acrylonitrile)

A previously proposed predictive format for elastic, storage and loss moduli is extended for the time-dependent compliance Db(t) of polymer blends. The format employs a two-parameter equivalent box model (EBM) and the data on the phase continuity of components in blends obtained by using modified general equations of the percolation theory. As input data, the compliances D1(t) and D2(t) and the critical volume fractions v1cr and v2cr (delimiting the interval of phase co-continuity in blends) of components are sufficient. To describe the effect of time on D1(t), D2(t) and Db(t) within the linear stress-strain region, a routinely used empirical equation was found suitable. Applicability of the proposed format is demonstrated on rubber-toughened polypropylene/poly(styrene-co-acrylonitrile) blends consisting of components with markedly different viscoelastic properties. The proposed predictive format fits fairly well the creep behavior of blends over the interval 0.1-10,000 minutes.