A Study On The Influence Of Poly(1,4-butylene Adipate) On The Phase Transition Of Poly(vinlidene Fluoride) During Crystallization

In our study,blend of poly(vinylidene fluoride)(PVDF)and poly(1,4-butylene adipate)(PBA)was prepared by using N,N-dimethylformamide(DMF)as a mutual solvent.The composition of the blend was 80/20 in ratio of weight percent.Differential scanning calorimetry(DSC),Fourier Transform infrared spectroscopy(FTIR),polarized optical microscopy(POM)and scanning electron microscopy(SEM)were used to study the influence of PBA blend on the phase transition of PVDF during isothermal crystallization.According to the DSC curves,a new phase of PVDF crystals with extremely high melting temperature was found during isothermal crystallization.This part of crystals was confirmed to be ? phase of PVDF that was transferred from ? phase through FTIR.It was called ?' phase because of its higher melting temperature than normal ? phase.We could determine that the ?-?' transition occurred in the solid state by quantitative analysis of the infrared results.Through the in-situ POM observation,the ?' phase distributed in the center of the spherulite,which meant the transition took place in the center and gradually extended to the whole spherulite.SEM micrographs told the difference between the ?' and y phase.The former was similar to the morphology of a lamellae but more curved and messy.The latter was like a cauliflower and the lamellae was C-like and messy in the whole spherulite.This transition was induced by the PBA component.During the crystallization of PVDF,PBA was distributed in the interfibrillar domains of PVDF.The molten PBA could enhance the activity of the segment in the amorphous region of PVDF.It is beneficial to the conformational transformation of PVDF molecule chain segment.Furthermore,it promoted the solid phase transition behavior of PVDF.