The purpose of this study was to accumulate material data for use in a simulation of morphology and crystallization in quenched slabs of isotactic polypropylenes (i-PP’s). The molecular weight effect on the crystallization kinetics of various i-PP’s were studied using isothermal and nonisothermal experiments. An experimental setup was constructed to measure the spherulite growth rate of i-PP’s using isothermal and nonisothermal melt crystallization experiments. The molecular weight effect on spherulite growth rate of i-PP’s was determined. Molecular weight effect on nuclei concentrations as a function of temperature was determined from growth and crystallization rate constants. The morphology and crystallization in quenched slabs of i-PP’s were determined from experiments and compared to computer simulations. The molecular weight effect on the degree of crystallinity and morphology was determined for i-PP during quenching.