A novel method of hyperbranched poly(amide-ester) modifying nano-SiO ₂ and study of mechanical properties of PVC/nano-SiO₂ composites

A new method of surface chemical modification of nano-SiO₂ was proposed in the paper. In the presence of catalyst, the active hydroxyl groups on the surface of nano-SiO₂ reacted with AB₂-type monomer (N,Ndihydroxyethyl-3-amino methyl propionate) by one-step polycondensation. And the product's Fourier transform infrared graphs and transmission electron microscopy (TEM) images proved that hyperbranched poly(amineester) (HPAE) was grafted from nano-SiO₂ surface successfully. Moreover, polyvinyl chloride (PVC)/modified nano-SiO₂ composites were made by melt-blending. The composites' structures and mechanical properties were characterized by TEM, scanning electron microscopy, and electronic universal testing machine. The results showed that nano-SiO₂ grafted by HPAE increased obviously in dispersion in PVC matrix, and mechanical properties of PVC were effectively improved. Additionally, it was found that mechanical properties of PVC/nano-SiO₂ composites reached the best when weight percent of nano-SiO₂ in PVC matrix was 1%. Compared with crude PVC, the tensile strength of HPAE grafted nano-SiO₂/PVC composite increased by 24.68% and its break elongation, flexural strength, and impact strength increased by 15.73, 4.07, and 184.84%, respectively