Investigations Of Structure And Properties In Silica Nanoparticles Modified Poly(Vinylidene Fluoride) And Poly(Lactic Acid)

Incorporation of silica nanoparticles into a polymer matrix can significantly affect the properties of the matrix. The prepared composites might exhibit improved thermal,mechanical, fire retardancy, optical and many other properties. In this paper, silica nanoparticles were used to modify poly（vinylidene fluoride）（PVDF） and poly（lactic acid）（PLA）. Then the structure and properties of the composites were investigated.1. The effect of silica nanoparticles on the properties of PVDF composites was studied.In order to produce uniformed silica nanoparticles in PVDF matrix, surface-grafting modification was used in this study by grafting γ-methacryloxypropyl trimethoxysilane（KH-570） onto the surface of silica nanoparticles. The surface-grafting reaction was confirmed by FTIR and TGA analysis. Scanning electron microscope revealed that silica nanoparticles had a good dispersion in PVDF; DSC and POM analysis showed that silica nanoparticles had a good effect on crystallization of PLA; The mechanical properties were also enhanced due to the αâ†'β phase transformation, which should play an important role in toughening of PVDF.2. The effect of silica nanoparticles on the properties of PLA composites was studied.3-Glycidoxypropyltrimethoxysilane（KH-560） was used to modify the silica nanoparticles.SEM and DMA results revealed that the compatibility between PLA and SiO₂ was improved; DSC and POM tests showed that nano-silica had a good effect on crystallization of PLA; The transparency analysis showed an increase in transparency of PLA which had great benefit for the application of PLA. The thermal stability, fire resistance and mechanical properties were also enhanced due to the addition of silica nanoparticles.3. The influence of silica core-shell particles on the structure and properties of PLA was investigated. Nano silica was modified by KH570. The modified SiO₂ was grafted with butylacrylate（BA）, methyl methacrylate（MMA） and glycidyl methacrylate（GMA） to prepare SiO₂-g-（MMA-co-BA-co-GMA） particles with different core-shell ratios. The research indicated that silica core-shell particles clustered partly in the PLA; DMA test showed that the silica core-shell particles were compatible with PLA in some degree. The blends showed much higher storage modulus with higher silica content; DSC showed the addition of silica core-shell particles was beneficial to the crystallization; TGA testified the improved heat resistance of PLA due to the silica particles; Impact test proved the improved toughness of PLA with the addition of silica core-shell particles.