Interphases in binary semicrystalline/amorphous polymer blends

Abstract

The authors present recent theoretical and experimental investigations on binary polymer blends that are completely miscible in the melt, but phase separate on cooling due to the crystallization of one component. Examples of such blends include poly(vinylidene fluoride) (PVDF) as the crystallizable component, mixed with one of the following amorphous polymers: poly(methyl methacrylate) (PMMA), poly(ethyl acrylate) (PEA), poly(vinyl pyrrolidone) (PVP), poly(vinyl esters) like poly(vinyl acetate), poly(vinyl propionate) or poly(vinyl butyrate, and a mixture of polyethyleneoxide as the crystallizable component mixed with PMMA. In all cases, on cooling, the mixture separates into several distinguishable phases: the crystal phase, which has been assumed to be constitued purely of the crystallizable polymer, an interphase whose composition is not clearly known, and an amorphous phase that is either a homogeneous mixture of both polymers in the interlamellar region or is a pure phase of non-crystallizable material in the interfibrillar or interspherulitic space.