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

摘要： 研究了亚苄基缩醛中羟基和亚苄基基团的个数对其在聚丙烯中溶解性和成核性能的影响，结果表明随着羟基数目的减少，亚苄基基团数目的增加，亚苄基缩醛在聚丙烯中的溶解性增强，对甲基亚苄基山梨醇、二（对甲基亚苄基）山梨醇、三（对甲基亚苄基）山梨醇和二（对甲基亚苄基）季戊四醇能够在聚丙烯结晶前从熔体中结晶析出的最低浓度分别为0.15%、0.20%、0.80%和4.00%，在此添加浓度下，成核聚丙烯的结晶温度分别提高了8.4、15.8、15.7、16.5℃，成核聚丙烯的弯曲模量提高了19.9%、35.8%、28.7%和18.6%，成核聚丙烯的雾度分别下降了12.5%、46.2%、7.4%和-17.4%。综合来看，含有两个羟基和两个亚苄基基团的二亚苄基山梨醇缩醛的成核效果最好，说明在设计亚苄基缩醛类聚丙烯成核剂时要兼顾分子结构对溶解性和成核性能的影响。

关键词: 亚苄基缩醛, 成核剂, 聚丙烯