It was proposed that the enhancement of PP melt strength was through a mechanism of physical knotting. PP chains intercalated into the spacing of platelets and became held, forming physical entanglements, which played a role similar to chemical crosslinking in rubber elastomers. XRD patterns showed that the diffraction peaks of all the four melting-intercalated polypropylene=clay nanocomposites (PPCNs) were shifted to higher d values, which indicated the intercalation of PP chains in the clay layers. ARES Rhe- ometer observation demonstrated that the out-of-phase vis- cosity and storage modulus of PPCNs were higher, and the lag angle ds were smaller than those of neat PP, which demonstrated the increased melt elasticity. The crystalliza- tion and melting behaviors, as well as nonisothermal crystal- lization kinetics of PP and PPCNs, were probed systematically by the DSC technique. At various cooling rates, the exothermic peaks of PPCNs shifted to higher tem- perature compared with that of neat PP. For a given sample, the value of t1=2 decreased with increasing cooling rate and at a given cooling rate, the value of t1=2 for PPCNs was lower than that for neat PP, indicating that the organoclay accelerated the crystallization process of PP.