交联聚氨酯水分散体的合成

将硅氧烷封端的含亲水基团的线性聚氨酯预聚体分散于水中 ,获得稳定的聚氨酯分散体 .由于硅氧基团水解、缩合 ,在分散体粒子内产生扩链交联反应 ,生成了交联水基聚氨酯分散体 .透射电子显微镜研究表明分散体粒径小、分布宽 .扫描电子显微镜研究了成膜结构及成膜性能与粒径的关系 .溶胀实验计算获得的两交联点之间的平均分子量与理论平均分子量相符 .研究还发现此分散体膜在干燥过程中可进一步交联 .膜的水溶胀及机械性能表明 ,此分散体具有极大的工业应用价值 .

SYNTHESIS AND CHARACTERIZATION OF CROSS-LINKED AQUEOUS POLYURETHANE DISPERSION

Silylate\|terminated polyurethanes with built\|in hydrophilic sites were synthesized.When the polymer is dispersed in water,the silane alkoxy end\|groups of the polymer undergo hydrolysis,followed by condensation to form a stable cross\|linked aqueous dispersion.TEM studies indicated that with more incorporation of hydrophilic sites,the particle size of the dispersion decreased.It was also found that the film property depended on the particle size when the crosslinking density in particels was much higher.The average molecular weight of the elastically effective network chain M c measured by swelling experiments shows fairly good agreement with the theoretical value of M c.It was also found that the cross\|linking density of the casting film may increase during the film formation and drying process.