Preparation And Property Studies Of Polyvinyl Chloride/Silica Particle Nanocomposites

In our work, two aminosilane coupling agents containing different numbers of ethoxyl groups, y-aminopropyltriethoxysiliane (APTES) and y-aminopropylmethydiethoxysilane (APMDES), were used for the surface modification of silica nanoparticles, and polyvinyl chloride (PVC) was grafted on the surface of modified nano-silica. Unmodified and modified silica nanoparticles were melt-compounded with PVC to prepare PVC/nano-SiO2 composites (PVC/SiO2, PVC/SiO2-APTES, PVC/SiO2-APMDES, PVC/SiO2-APTES-PVC and PVC/SiO2-APMDES-PVC). The PVC composites and the pure PVC were characterized using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), vicat softening temperature and tensile measurement. The results showed that compared with those of pure PVC, thermal stabilities of all the nanocomposites were improved. PVC/SiO2 composites exhibit a higher tensile strength and elongation-at-break, PVC/SiO2-APTES and PVC/SiO2-APMDES composites exhibit higher tensile strength and a lower elongation-at-break. Tensile strength and elongation-at-break of PVC/SiO2-APTES-PVC and PVC/SiO2-APMDES-PVC composites were almost unchanged.In addition, under acidic conditions, the strong electrostatic attraction between cationic SiO2-APTES nanoparticles and negative charged Na+-MMT clay particles resulted in the formation of SiO2-APTES-MMT nanohybrids during the mixing process. SiO2-APTES-MMT nanohybrids with the different weight ratios of MMT to SiO2-APTES were melt-compounded with PVC to prepare PVC/SiO2-APTES-MMT composites. Thermal stabilities of all the composites were almost unchanged compared with those of pure PVC. When the weight ratio was 1/3, the PVC/SiO2-APTES-MMT composites exhibit the hightest tensile strength and the lowest elongation-at-break.