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

Abstract A new method of surface chemical modification of nano‐SiO ₂ was proposed in the paper. In the presence of catalyst, the active hydroxyl groups on the surface of nano‐SiO ₂ reacted with AB ₂ ‐type monomer ( N , N ‐dihydroxyethyl‐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(amine‐ester) (HPAE) was grafted from nano‐SiO ₂ surface successfully. Moreover, polyvinyl chloride (PVC)/modified nano‐SiO ₂ 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‐SiO ₂ 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‐SiO ₂ composites reached the best when weight percent of nano‐SiO ₂ in PVC matrix was 1%. Compared with crude PVC, the tensile strength of HPAE grafted nano‐SiO ₂ /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. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers