Mechanical study of poly(vinylidene fluoride)-poly(methyl methacrylate) amorphous blends

Amorphous films of poly(vinylidene fluoride)-poly (methyl methacrylate) were prepared by initial precipitation from a solvent and rapid solidification at ≈ 15 °C from the molten state. The PVDF/PMMA compositions studied were 25/75, 45/55, 50/50, 55/45, 60/40 and 75/25. X-ray scattering analysis suggests that mixture of the two components throughout the composition range studied occurs at a molecular level. The parallel decrease of the microhardness, which obeys a simple expression:H _blend =H _PMMA (1−φ) (φ being the PVDF concentration) and the glass transition temperature,T _g, following the predictions, of Gordon and Taylor, reveals that the depression of microhardness is caused by the shift ofT _g towards lower temperatures. It is pointed out that the effect of PVDF molecules is to act as a softening agent within the PMMA component.