Evidence for a crystal-amorphous interphase in PVDF and PVDF/PMMA blends

Dielectric relaxation studies and absolute small-angle X-ray investigations give evidence that amorphous interlamellar regions in partially crystalline PVDF/PMMA blends consist of two phases: a pure amorphous PVDF phase and a homogeneously mixed PVDF/PMMA phase. The local phase separation which occurs, despite favourable interactions between PMMA and PVDF, is attributed to a PVDF crystal-amorphous interphase which rejects PMMA segments. The thickness of this interphase is found to be of the order of 2.5 nm.