Polyvinylidene Fluoride And Fluorine-containing Copolymer Blend Compatibility And Crystallization Properties

In this article the blend films of Polyvinylidene fluoride (PVDF) and three kind its copolymers were prepared:PVDF/P(VDF-HFP)(poly vinylidene fluoride-hexafluoro propylene),PVDF/P(VDF-CTFE) (poly vinylidene fluoride-chlorotrifluoro ethylene)and PVDF/P(VDF-TrFE) (poly vinylidene fluoride-trifluoro ethylene). The influence of heat treatment and different rates of blended polymers on the compatibility, crystallization and morphology was discussed.The DSC results show that the PVDF/P(VDF-HFP) blends are miscible when the content of PVDF is no more than 30wt%, and shown good miscibility after amealing at different temperature. P(VDF-CTFE) shows a miscibility when blended with PVDF that made from the solution, but the cooling simples from melting temperature show less miscibility because of the phase saparation. The PVDF/P(VDF-TrFE) blend simples are the same as P(VDF-CTFE) blend, when the film made at 60℃from the solution, but less miscibility after amealing at melting temperature, phase aspiration happens too.The XRD results show that P (VDF-HFP) leads to moreβ-crystalline forming in the blend, andβ-crystalline is the key to show good piezo- and ferro-electricity for the polymers, particularly the simple with 10wt% PVDF shows moreβ-crystalline after various heat treatmeat. The pure P(VDF-CTFE) films have no crystal structure founding, but get good effect on the crystal of PVDF, leads to moreβ-crystalline in the blends. P(VDF-CTFE) shows perfect crystal ability, all the blends just show the crystal characteristic of P(VDF-CTFE), the exist of PVDF show less influence in the blend.The SEM results show that The porous disappeared between the adjacent spherulite of the P(VDF-HFP) membrane, result from the PVDF in the blend, the dense semicrystalline polymer blend forms with the P-crystalline as the matrix phase. PVDF disperses in the phase of P(VDF-CTFE) uniformly, and the degree of uniform for raieses as the reduce of PVDF in the blend. the PVDF/P(VDF-TrFE) blend with 10% PVDF shows a specially crystal morphology different from pure PVDF and P(VDF-TrFE), it is because of the foundation of eutectic region. As the decrescence of PVDF in the blend, the eutectic region disappears slowly, PVDF disperses in the phase of P(VDF-TrFE) uniformly, but different from the PVDF/P(VDF-CTFE) blend, PVDF disperses as a sigle spherulite in the PVDF/P(VDF-TrFE).