Preparation And Properties Investigation Of PVDF Nanocomposites

PVDF has been widely investigated by reseachers in recent years due to its excellent properities, such as weather resistance, chemical resistance and dielectricity. In this paper,nano montmorillonoid(MMT) and SiO2 composite microsphere were used to blend with PVDF and the properties of PVDF nanocomposites were studied in detail. The main researches are as follow:Hexadecyl trimethyl ammonium bromide was used to modify.MMT and the orgnic MMT was obtained(OMMT). The influence of MMT and OMMT on the properties of PVDF was investigated. The FTIR, DSC and X-ray results showed the PVDF transfered from α crystal to γ crystal when OMMT was used to blend with PVDF. At the same time,OMMT improved the tensile toughness of PVDF. When the OMMT content was 2%,200% elongation at break was achieved. On the othe hand, MMT had no influence on the crystal transformation and induced the decreased tensile toughness.The results indicated that only 01% OMMT could induce the transformation of PVDF from α crystal to γ crystal. The fracture toughness of PVDF was improved. 350%elongation at break was reached when the content of OMMT was 0.1%. The polarizing microscope(POM) results showed the crystallization rate and crystal size decreased significantly due to the addition of OMMT. The change of crystal phase and the decrease of spherulite size improved the transparency of PVDF. When the thickness of the films was0.5mm, the transparency improved from 60% for the pure PVDF to 86% for the modified PVDF with 0.1% OMMT addition.In this part, SiO2 composite microsphere was prepared and blended with PVDF. The SiO2 composite microsphere improved the impact toughness of PVDF and impcat strength of 1000J/m was achieved. At the same time, the yield strength of PVDF had litte decrease which indicated the good stiffness and toughness banlance for the blends. SEM results showed the core-shell morphology of the SiO2 composite microsphere and most of the particles dispersed in the PVDF matrix uniformly. Toughening mechanism results showed the transformation of crystal from α to β and shear yielding of the matrix were the major reasons for the toughness improvement.