The effects of the inorganic particle size and the surface chemicals on the photo-oxidation of PP/CaCO3 composites are investigated

especially from the aspect of interface.Firstly

it is at the interface that the effect of filler particles on the photo-oxidation of PP matrix takes place.The interfacial area and chemicals of CaCO3particles are proved to be key factors that change the photo-oxidation rate of PP.A larger interfacial area leads to a faster photo-oxidation

so the PP/nano-CaCO3composite (PP/nmCaCO3) photo-degraded faster than the PP/micro-CaCO3composite (PP/mCaCO3) with the same load of CaCO3.Surface treatment with different coupling agents changes the surface chemicals of CaCO3 and thus the photo-oxidation rate.Based on this

a model of the photo-oxidation of polymer composites was developed

and the reaction rate formula was put forward for the first time.Secondly

an interfacial enlargement experiment

which is also the first trial in this field

was carried out.This experiment confirmed that the surface chemicals on CaCO3 particles largely accelerated the aging of PP during photo-oxidation.Meanwhile

titanate treated CaCO3 could accelerate the photo-oxidation of PP greatly

and a synergistic effect between titanate and CaCO3 was observed.