The crystalline structures, morphologies, and mechanical properties of poly（vinylidene fluoride）/clay nanocomposites were studied using X-ray diffraction（XRD）, transmission electron microscopy（TEM）, Fourier transform infrared spectroscopy（FTIR）, polarized optical microscopy（POM）, and tensile tests. The results of XRD and TEM show that organoclays are dispersed in the poly（vinylidene fluoride）（PVDF） matrix. A clay-induced crystal transformation from α-phase to β-phase of PVFD was confirmed by XRD and FTIR. Clay layers restricted the growth of spherulite. The tensile tests indicate that the tensile modulus and yield strength as well as the elongation at break decrease when clay is loaded.
SONG Yu-mingZHAO Zhu-diYU Wen-xueZHENG Wei-taoLI BoYANG Xiao-weiCHEN Xin-fang
Poly(vinylidene fluoride)(PVDF)/montmorillonite(MMT)nanocomposites were prepared by melt blending a kind of organically modified montmorillonite with PVDF.The morphological structures of the nanocomposites were studied using X-ray diffraction(XRD),transmission electron microscopy(TEM),Fourier transform infrared(FTIR)spectroscopy,and differential scanning calorimetry(DSC).The results indicate that organically modified montmorillonites are in the form of intercalation,exfoliation,and fragments in the PVDF matrix.For the composites,the(001)peak position of MMT was found to shift to a lower angle in XRD patterns,and some MMT fragments could be observed under TEM.MMT loading was favorable to producing the piezoelectric beta phase in the PVDF matrix and caused internal stress in a crystals.At the same time,the crystallinity and spherulite size of PVDF decreased with the MMT content.MMT induced beta phase is stable even at high temperatures(160℃).For these changes in morphological structures,some possible explanations were proposed based on the experimental results.
SONG YuMing ZHAO ZhuDi YU WenXue LI Bo CHEN XinFang
Poly（vinylidene fluoride）（PVDF）/multi-walled carbon nanotube（MWCNT） nanocomposites were prepared by means of ultrasonic dispersion method. X-ray diffraction（XRD） results indicate that incorporating MWCNTs into PVDF caused the formation of β phase. A thermal annealing at 130 ℃ confirmed that the β phase was stable in the nanocomposites. Differential scanning calorimetry（DSC） results indicate that the melting temperature slightly increased while the heat of fusion markedly decreased with increasing MWCNT content. The tensile strength and modulus of PVDF were improved by loading the MWCNTs. The scanning electron microscopy（SEM） observations showed that MWCNTs were uniformly dispersed in the PVDF matrix and an interfacial adhesion between MWCNT and PVDF was achieved, which was responsible for the enhancement in the tensile strength and modulus of PVDE.
