Effect of calcium salts of glutaric acid and pimelic acid on the formation of beta crystalline form in isotactic polypropylene

The effect of calcium glutarate (Cagt) and calcium pimelate (Capt) on the formation of beta crystalline form in isotactic polypropylene (iPP) after isothermal crystallization at 130 degrees C for 30 min has been investigated. The maximum K(WAXD) and K(DSC) values were 31.97% and 38.06%, respectively, for iPP doped with 0.2 wt.% Cagt. The maximum values of K(WAXD) and K(DSC) were 73.60% and 68.44% for iPP doped with 0.3 wt.% and 0.15 wt.% Capt, respectively. The crystal size of iPP doped with Capt is finer than that of iPP doped with Cagt. It is shown that the beta nucleation ability of Capt is superior to that of Cagt. The difference in the beta nucleation ability between Cagt and Capt is explained by the structural difference of the nucleators with beta-iPP.