Modification of the polycarbonate/poly(vinylidene fluoride) interface by poly(methyl methacrylate).: Effect on the interfacial adhesion and interfacial tension

Polycarbonate (PC) and poly(vinylidene fluoride) (PVDF) are two immiscible polymers which form two-phase blends with weak interfacial adhesion and high interfacial tension. This situation may be changed by the addition of poly(methyl methacrylate) (PMMA), which concentrates preferably in the PVDF-rich phase, but also at the PVDF/PC interface. The interfacial activity of PMMA was estimated by the measurement of the interfacial adhesion and interfacial tension in relation to the PMMA content in the PVDF/PC blends. The interfacial adhesion between PC and homogeneous PVDF/PMMA blends of various compositions was measured by the dual cantilever beam technique. The imbedded fiber retraction method was used for the measurement of the interfacial tension. A very beneficial effect was observed when PVDF was premixed with PMMA amounts increasing up to ca. 35 wt.-%. Beyond that content, the improvement tends to level off.