Morphological and Structural Development of Polypropylene and Polystyrene Blends During Solid State Mechanochemical Milling

摘要

The homogeneous dispersion and in situ compatibilization of Polypropylene/Polystyrene blends were achieved through an environmentally friendly mechanochemical approach called solid state mechanochemical milling using pan-mill equipment at ambient temperature. Scanning electron microscopy and polarizing microscopy showed that after milling, the size of Polystyrene spherical dispersed-phase domains was significantly reduced, approaching an average diameter of approximately 1 (mu)m. Fourier transform infrared spectra and fluorescence emission spectroscopy indicated the in situ block copolymer formation of Polypropylene/Polystyrene blends during solid state mechanochemical milling. The mechanism of mechanochemical compatibilization was ascribed to the interpolymer radical coupling reactions during milling. Differential scanning calorimeter analysis illustrated the size reduction of Polypropylene spherulites and 7 deg C of increase in crystallization peak temperature. It could be ascribed to the heterogeneous nucleation effect of the block copolymer, which was in situ formed during solid state mechanochemical milling. The formation of block copolymer was further confirmed by the sharp increase in shear viscosity after 20 cycles of milling.