The liquidliquid phaseseparation (LLPS) and isothermal crystallization behavior of isotactic polypropylene/ethylenepropylene rubber blend (iPP/EPR) were investigated by using small angle laser light scattering (SALLS)

differential scanning calorimetry (DSC)

phase contrast microscopy (PCM) and polarized optical microscopy (POM).Results reveal that LLPS of (50/50

W/W) iPP/EPR blend happens at temperatures above the melting point of iPP

and its kinetics follows the spinodal decomposition (SD) mechanism.The apparent diffusion coefficient (Dapp) and the spinodal temperature (Ts) of the iPP/EPR samples were calculated on the basis of the CahnHilliard theory.Moreover

it is found that the Dapp increases with the increase of temperature

representing the LCST behavior of iPP/EPR.The development of phase morphologies could be obtained by quenching in liquid N2 the iPP/EPR samples subjected to annealing with different time at 200℃.On the other hand

the structure of iPP/EPR melt appears nearly homogenous at the beginning of LLPS.Furthermore

the co-continuous phases form

and the phase connectivity grows until macroscopic spherical texture generates.Both the increases of phase separation time (tps) and phase separation temperature (Tps) result in the decrease of the crystallization rate.The kinetic results indicate that the Avrami model is qualified for describing the isothermal crystallization of iPP/EPR.It is believed that the degree of phaseseparation has little effect on the crystallization kinetics and the crystallization gives priority to instantaneous nucleation and threedimensiongrowth.