The non-isothermal crystallization kinetics of polypropylene grafted polyurethane (PP-g-PU) copolymers under the different cooling rate has been studied by DSC．A kinetic equation for nonisothermal crystallization was employed to analyze the crystallization characteristics of PP and PP-g-PU. The results show that in the range of cooling rate of 2.5 to 40 K／min

the kinetics of non-isothermal crystallization of PP and PP-g-PU with different PU content can fit the Avrami equation and a combination of Avrami-Ozwa method. The presence of the PU branches in PP-g-PU results in less crystallization enthalpy and higher crystallization temperature upon cooling．All the PP-g-PU copolymers have higher nucleation rate and overall rate of crystallization assuming that the spherulitic growth was initiated by heterogeneous nucleation alone

as characterized by the higher values of Zc and low values of t1/2 than those of pure PP．The crystallization rate is not only dependent upon the cooling rate

but also dependent on the composition ratio of PP-g-PU copolymers. It was found that

due to stronger hydrogen bonding effect among the PU branch chains

the mode of nucleation and the growth of the crystallites changed after grafting. The hydrogen bonding effect can accelerate the heterogeneous nucleation by strengthening the adsorption effect between PP chains

and result in different crystalline behavior from other PP copolymers

as proved by the fact that the n values of PP-g-PU copolymers increased with increasing cooling rate．