Poly(n‐butyl acrylate)/polystyrene interpenetrating polymer networks and related materials I. Dynamic mechanical spectroscopy and morphology

Abstract

Abstract A series of interpenetrating polymer networks, IPN's, and semi‐1 IPN's of poly(n‐butyl acrylate) and polystyrene were prepared. The glass transition behavior via dynamic mechanical spectroscopy (DMS) and the morphology via transmission electron microscopy (TEM) were studied as a function of composition ratio and crosslink density. Transition‐broadening was observed at low crosslink concentrations, while a single broad glass transition peak at an intermediate position was attained at high crosslink density levels. A cellular domain structure was the morphological characteristic of those IPN's and semi‐1 IPN's possessing a low cross‐link density and mid‐range composition ratio. At higher levels of crosslink density, irregular shapes of the domain morphology prevailed. Phase connectivity was also observed at high polymer II compositions. Theoretical phase domain sizes of polymer II were calculated using both the theories developed by the present authors and that published earlier by Donatelli, et al., and were found to agree with the experimental domain sizes. While the theory was developed for uniform spheres, some of the domain structures observed experimentally for high polymer II contents had connectivity and/or a cylindrical shape.