Effects of nanometer-TiO2 surface modification and concentration on the mechanical performances of polypropylene/polyamide maleic anhydride-grafted polypropylene composite

A new hyperdispersant agent with maleic anhydride monoester as anchoring group, butylmethacrylate as solventable chain, and styrene (St) as functional group was synthesized, and named SMB. Also, the effects of nanometer-TiO2 (nano-TiO2) modification and concentration on the mechanical properties of polypropylene/polyamide/maleic anhydride-grafted polypropylene (70/30/5 by weight) composites were investigated. The experimental results indicated that the mechanical properties of polypropylene/polyamide 6/M blend reduced with the addition of p-TiO2 (unmodified nano-TiO2) due to the aggregation of nanoparticles, but improved by the addition of t-TiO2 (modified by titanate coupling agent TDI) or SMB-TiO2 (modified by hyperdispersant agent SMB), and SMB-TiO2 seemed to be more effective. The optimum content of SMB-TiO2 was found to be 3wt%. In order to understand the reinforcing mechanisms of nanoparticles, SEM and TEM pictures were carried out, which revealed that SMB-TiO2 mainly distributed at the interface of polypropylene and polyamide 6 in nanoscale as compatibilizer. It could be due to the surface of nano-TiO2 coated with SMB, and the carboxy group of SMB could react with the functional group of PA6; meanwhile, the solventable chain had good compatibility with PP, and so the interaction between PP and PA6 increased in the presence of SMB-TiO2. Consequently, PP/PA6/M blend could be simultaneously strengthened and toughened by SMB-TiO2.