摘要： 在准确测定水性聚氨酯分散体端氨基含量的基础上，采用二异氰酸酯对分散状态下的水性聚氨酯分散体进行二次扩链，研究了不同条件下二次扩链前后分散体端氨基含量、涂膜力学性能以及分散体粒径的变化。 研究表明:二次扩链剂可以与水性聚氨酯分散体的端氨基反应;二次扩链可大幅度提高涂膜拉伸强度，而涂膜模量略有上升，说明反应形成扩链而非交联;扩链后分散体粒径略有增加，表明二次扩链不影响分散体稳定性。

关键词: 水性聚氨酯, 二次扩链, 力学性能, 平均粒径

Abstract: based on the accurate determination of the amino end group of the aqueous polyurethane dispersion, the polyurethane was re-extended by using diisocyanate to increase its molecular weight. The amino end group content, film mechanical properties and particle size of aqueous polyurethane dispersion prepared under different condition were studied. The results showed that the secondary chain extender could react with the amino end group of aqueous polyurethane dispersion, moreover, the tensile strength of the cured film was significantly increased while the film modulus and the particle size of aqueous polyurethane dispersions were slightly affected, indicating that the secondary chain extension process had no effect on the stability of the polyurethane dispersion.

Key words: aqueous polyurethane, secondary chain extension, mechanical properties, average particle size