利用差示扫描量热法和X 射线衍射法研究了稀土配合物( β 成核剂) 改性无规共聚聚丙烯( PPR) /等规聚丙烯( iPP) 共混物的力学性能和结晶结构的关系．结果表明: 添加0. 05%的β 成核剂能够大幅度地提高PPR、PPR/iPP( 质量比分别为70 /30、50 /50、30 /70)共混物、iPP 的冲击韧性，缺口冲击强度分别从42. 7、33. 7、14. 5、8. 3、5. 1 kJ /m2 上升至87. 8、63. 4、29. 3、13. 9、8. 2 kJ /m2，而拉伸强度下降幅度均在10% 以内; 加入0. 05% 成核剂后，PPR/iPP( 质量比70 /30) 共混物的熔融峰温从161. 9℃降至149. 8℃，β 晶相对含量从45. 3%增至53. 1%，有明显的β 晶成核促进作用; 冲击断面的扫描电镜照片显示，该体系呈现明显的韧性断裂特征; 成核剂用量增至0. 20% 时，共混物熔融峰温为159. 8 ℃，β晶相对含量为45. 1%，成核剂对共混物β 晶的成核作用减弱，增韧作用降低．

In this paper,the relationship between the mechanical properties and the crystalline structure of propylene random copolymer ( PPR) /isotactic polypropylene ( iPP) blends modified by a rare earth complex ( β-nucleator) was investigated by means of DSC and XRD. When the dosage of β-nucleator is kept at 0. 05%,it is found that ( 1) the impact strengths of PPR,PPR/iPP( 70 /30,50 /50 and 30 /70 in mass ratio,respectively) blends and
iPP increase from 42. 7,33. 7,14. 5,8. 3 and 5. 1 kJ /m2 to 87. 8,63. 4,29. 3,13. 9 and 8. 2 kJ /m2,respectively,while the tensile strengths all decrease by less than 10%; ( 2) the melting temperature of PPR/iPP ( 70 /30 in mass ratio) blend decreases from 161. 9 ℃ to 149. 8 ℃ and the relative content of β-form crystal increases from 45. 3% to 53. 1%,which reveals a remarkable nucleating promotion to β-form crystal; and ( 3) there exist typical ductile fractures in the impact-fractured sections of the blend,which is verified by the SEM photographs. Moreover,when the dosage of β-nucleator increases to 0. 20%,the melting temperature of the blend and the relative content of β-form crystal respectively reach 159. 8℃ and 45. 1%,and the nucleation to β-form crystal of the blend weakens,thus resulting in a decrease in the impact toughness.