The influence of the composition ratio of pimelic acid/calcium stearate bicomponent nucleator on the 0 crystal form content of isotactic polypropylene (iPP) had been studied at the crystallization temperature of 120 degrees C and duration of 30 min. It was found that the crystal form content increased continuously with increasing amount of calcium stearate at the constant amount of 0.15% pimelic acid. High P crystal form content polypropylene could be produced when the amount of calcium stearate was greater than 0.30% (the mass composition ratio of pimelic acid/calcium stearate was less than 1/2, the mole ratio was less than 1.89/1). It was shown that pimelic acid and calcium stearate could react to produce a high effective nucleator (calcium pimelate) "in situ" during the melt-mixing of iPP and the bicomponent nucleator. The influence of crystallization temperatures (100-140 degrees C) on the P crystal form content of iPP had also been studied at the constant composition ratio of 0.15% pimelic acid/0.5% calcium stearate (the calcium pimelate produced in situ was 0.16%, which was calculated from stoichiometry). It was found that the P crystal form content increased continuously with increasing crystallization temperature and it maximized at 130 degrees C. P Crystal form content decreased sharply at the crystallization temperature of 140 degrees C. It was shown that beta -> a modification transformed between 130 and 140 degrees C. (C) 2007 Wiley Periodicals, Inc.nc.