阴离子原位聚合橡胶改性尼龙6形态结构研究

Morphological structure of rubber-modified nylon-6 prepared by anionic in-situ polymerization

采用脂肪族聚异氰酸酯(HDI脲二酮)接枝端羟基聚丁二烯液体橡胶(HTPB),再用己内酰胺封端异氰酸酯基团,制得橡胶改性剂,通过阴离子聚合制得液体橡胶改性尼龙6树脂。红外分析表明,HDI脲二酮接枝到HTPB的羟基上后被己内酰胺成功封端,进而发生阴离子聚合生成橡胶改性尼龙共聚物。冲击断面分析,当橡胶质量含量高于15%以后,改性尼龙树脂表现出明显的韧性断裂,脆断后甲苯刻蚀表明,随着橡胶活化剂含量增加,未参与聚合橡胶含量增加,导致橡胶微相尺寸变大且均匀性下降。在180℃条件下,聚合生成橡胶改性尼龙6树脂表现为α晶型,橡胶的加入并没有改变尼龙6的晶型;树脂熔融再速冷结晶后,尼龙6以亚稳定γ晶型为主,随着橡胶含量的增加,α晶型明显增强,说明橡胶相的存在有助于形成较稳定的α晶型。

The rubber modifier was prepared by grafting hydroxyl-terminated liquid polybutadiene rubber（HTPB）with HDI urea diketone and blocking the isocyanate group with caprolactam,and the liquid rubber-modified nylon-6resin was prepared by the anionic polymerization.The infrared analysis showed that,HDI urea diketone was successfully blocked by caprolactam after grafting on hydroxyl of HTPB,and then,the rubber-modified nylon copolymer was generated by the anionic polymerization.After the impact section analysis,when the rubber content was higher than 15%,the resin showed the obvious ductile fracture,the toluene etching after the brittle failure showed that the rubber which did not participate in the polymerization increased when increasing the content of rubber activator,which caused that the micro-phase size of rubber increased and the uniformity reduced.At 180℃,the resin generated by the polymerization showedαcrystal form,and the addition of rubber did not changed the crystal form of nylon-6;and after the resin was molten and subjected to the cold crystallization rapidly,the crystal form of nylon-6 was mainly metastableγcrystal form,and as the rubber content increased,αcrystal form was obviously enhanced,which showed that the existence of rubber phase was beneficial to form the stableαcrystal form.