Abstract
The effect of modification with polypropylene-polyacrylate block polymer (diblock polymer) on the microstructure and mechanical properties of particle-filled polypropylene (PP) were investigated. We measured the dynamic mechanical properties of diblock polymer filled with Mg(OH)2, Al(OH)3, CaCO3, Al2O3, SiO2 and talc to discuss the interaction between the particles and functional groups i.e. –COOH in diblock polymer. The shifts of b-transition peak temperature in tan d by ca. 15 °C were observed when using the alkali filler particles such as Mg(OH)2, Al(OH)3, CaCO3, and Al2O3. On the other hand, in the case of SiO2 and talc particles, the b-peak temperature was independent of the filler contents. This phenomenon showed the following explanation that force of interactions between –COOH groups on diblock polymer and the surfaces of alkali filler particles was larger than that of interactions between diblock polymer and SiO2, or talc particles. The modulus of PP-Mg(OH)2, or CaCO3 (alkali filler) composite gradually decreased by the modification of the filler with diblock polymer. The modification of the alkali fillers by diblock polymer for PP-filler composites improved the yield strength of PP. These results suggested that the diblock polymer was strongly interacted between matrix PP and the alkali filler surfaces, and also suggested that the strong interaction between particle surface and –COOH group in diblock polymer was one of the key factors controlling the mechanical properties of the PP-filler composites.
