The unit cell parameter of polypropylene crystallized with different method and condition was studied:curves of wide angle X-ray diffraction(WAXD) are determined by stepwise scanning method

X ray multi peaks resolution program and simulation program of unit cell parameter developed by the general inverse matrix method are used as data processing of determined results.It is shown that effect of crystallization condition on the unit cell parameter is marked.Crystal density of samples decrease in order:crystallized in 145℃ for 5h (0.970g·cm-3)>quench(0.950g·cm-3)>orystallized out from solution (0.937g·cm-3).Thermal behavior of these samples are inverstigated by differential scanning calorimeter.It is shown that the melt peak temperature I relaties to crystal density.