The effect of multifunctional monomer triallyl trimellitate (TATM) on the melt flow rate (MFR) and rheological behavior of maleic anhydride grafted polypropylene (maleated PP) was studied.TATM is not effective for stabilizing the MFR of maleated PP based on PP powder not containing antioxidant.However

TATM can effectively stabilize the MFR of maleated PP when PP powder was first melt compounded with antioxidant and then used as grafting raw material.The rheological results showed that the grafted PP based on PP pellets containing antioxidant had higher melt elasticity

indicating some grafted or crosslinked structure.The remarkable differences of the rheological results between maleated PP based on polypropylene powder and polypropylene pellets are discussed through the mechanism of free radical grafting reactions.The effect of TATM on stabilizing MFR is due to its effect on increasing the melt elasticity

which can offset the inevitable reduction of shear viscosity caused by β scission reaction of PP molecules during melt grafting.The differences of antioxidant content in PP powder and PP pellets can strongly influence the PP degradation during melt processing

therefore TATM shows different effects in different PP systems.