叔碳酸酯改性聚丙烯酸酯乳液的制备及性能研究

以叔碳酸酯(ACE)为改性单体,以丙烯酸酯基脲(W50)为功能助剂,采用预乳化聚合工艺制备了一系列叔丙乳液。通过DLS、DSC、SEM等分析技术对乳液的结构、乳胶膜性能进行表征,并测试了乳液漆膜的耐水性与力学性能。结果表明:所制备的乳液乳胶粒子均呈球形颗粒,粒径分布较窄,乳液粘度较低,在单体配比BA:ACE:MMA=5:5:10,且W50含量为2 wt%时,乳液粒径在230 nm左右,乳胶膜玻璃化温度为27.2℃,漆膜附着力达到1级,柔韧性达到轴棒7,抗冲击强度为50 cm且耐水性良好。该性能达到高铁无砟轨道板中钢筋涂层的要求。

Synthesis of Urea by Ammonolysis of Propylene Carbonate

Studying urea formation by ammonolysis of propylene carbonate in a liquid phase showed that this process is two-stage, and proceeds through preferred formation of 2-hydroxypropyl carbamate, besides, the rate of the first stage is much higher than the rate of the second stage （urea formation）. With the aid of the HPLC and HPLC/MS methods found some other intermediate products and offered consecutive-parallel scheme of the process. The obtained results explain the composition of impurities obtained during the production of the 13C-urea for diagnostic breath tests.