原位聚合法改性制备核壳结构WPUA复合材料

Preparation of WPUA Composites with Core-Shell Structure by In-Situ Polymerization

采用水性聚丙烯酸酯(WPA)为核,水性聚氨酯(WPU)预乳液为壳,基于原位聚合法制备具有核壳结构的WPUA复合乳液,探究制备过程的主要影响因素并表征WPUA复合薄膜。结果表明:制备复合乳液的最佳反应时间为3 h,聚氨酯(PU)、丙烯酸(AA)和十二烷基苯磺酸钠(SDBS)的最佳质量分数分别为12%、3%和4%。反应过程中用碳酸氢钠调节pH值为4,反应后用氨水进行调节pH值在7~8之间,可得到稳定性好的WPUA复合乳液。此时聚合物之间相容性较高,又能够有效防止絮凝现象;复合材料伴有蓝光,反应速率稳定。红外测试表明:WPUA出现氨酯键和聚丙烯酸酯(PA)的特征吸收峰,表明已经成功引入PA。改性WPUA涂膜的力学性能和耐水性能显著增强,其抗拉强度和吸水率分别为28.47 MPa和7.62%,较WPU改善49.2%和62%。SEM和TEM测试发现:WPUA涂膜中,线性PU有序化程度受到破坏,聚合反应已经在核壳结构的表面发生,预乳液中WPA和WPU结合,形成稳定的核壳结构。

WPUA composite emulsion with core-shell structure was prepared based on in-situ polymerization using waterborne polyacrylate(WPA) as core and waterborne polyurethane(WPU) pre-emulsion as shell. The main factors affecting the preparation process were studied and the WPUA composite film was characterized. The results show that the optimal reaction time for preparing composite emulsion is 3 h, the optimum mass fractions of polyurethane(PU), acrylic acid(AA) and sodium dodecylbenzene sulfonate(SDBS) are 12%, 3% and 4%, respectively. Sodium bicarbonate was used to adjust the p H value to 4 in the reaction process, and ammonia water was used to adjust the pH value to 7~8 after the reaction to obtain the WPUA composites emulsion with good stability. At this time, the compatibility between the polymers is high, and the flocculation phenomenon can be effectively prevented. The composite had blue light and the reaction rate is stable. The FTIR test of WPUA composite film shows that PU has the characteristic absorption peaks of urethane bond and polyacrylate(PA), indicating that PA is successfully introduced into PU. The mechanical properties and water resistance of the modified WPUA are significantly enhanced, and the tensile strength and water absorption are28.47 MPa and 7.62%, respectively, which are 49.2% and 62% higher than those of WPU, respectively. SEM and TEM tests show that the degree of ordering of linear PU is significantly damaged in the WPUA coating. The polymerization reaction takes place on the surface of the core shell structure. The WPA and WPU contain in the pre-emulsion formed a stable core-shell structure.