关键词: 亚苄基缩醛, 成核剂, 聚丙烯

Abstract: The effect of molecular structure of benzylidene acetals on their solubility and nucleation in isotactic polypropylene(iPP) was studied,selecting mono-p-methylbenzylidene sorbitol,di-(p-methylbenzylidene) sorbitol,tri-p-methylbenzylidene sorbitol and di-(p-methylbenzylidene) pentaerythritol as objects for study. Differential scanning calorimetry(DSC) results indicated that the polarity of benzylidene acetal decreased gradually with decreasing number of hydroxyl group and increasing number of benzylidene group,and the solubility of benzylidene acetals in iPP increased gradually. The saturated concentrations of these benzylidene acetals in iPP were 0.15%, 0.20%,0.80% and 4.00%,respectively. With this addition amount, the crystallization temperature of the nucleated iPP increased by 8.4,15.8,15.7 and 16.5℃,and the flexural modulus of nucleated iPP increased by 19. 9%，35. 8%，28. 7% and 18. 6%,and the haze of iPP decreased by 12.5%，46.2%，7.4% and -17.4%. Di- (p-methylbenzylidene) sorbitol was the best nucleating agent in these benzylidene acetals,which indicated that the effect of molecular structure of benzylidene acetals on their solubility and nucleation in iPP should be given consideration.The effect of molecular structure of benzylidene acetals on their solubility and nucleation in isotactic polypropylene(iPP) was studied,selecting mono-p-methylbenzylidene sorbitol,di-(p-methylbenzylidene) sorbitol,tri-p-methylbenzylidene sorbitol and di-(p-methylbenzylidene) pentaerythritol as objects for study. Differential scanning calorimetry(DSC) results indicated that the polarity of benzylidene acetal decreased gradually with decreasing number of hydroxyl group and increasing number of benzylidene group,and the solubility of benzylidene acetals in iPP increased gradually. The saturated concentrations of these benzylidene acetals in iPP were 0.15%, 0.20%,0.80% and 4.00%,respectively. With this addition amount, the crystallization temperature of the nucleated iPP increased by 8.4,15.8,15.7 and 16.5℃,and the flexural modulus of nucleated iPP increased by 19. 9%，35. 8%，28. 7% and 18. 6%,and the haze of iPP decreased by 12.5%，46.2%，7.4% and -17.4%. Di- (p-methylbenzylidene) sorbitol was the best nucleating agent in these benzylidene acetals,which indicated that the effect of molecular structure of benzylidene acetals on their solubility and nucleation in iPP should be given consideration.

Key words: benzylidene acetal, nucleating agent, polypropylene