高等学校化学研究 ›› 2023, Vol. 39 ›› Issue (5): 782-789.doi: 10.1007/s40242-023-3067-4
BI Xiang1, LI Minggang2, LU Min1, YOU Jiangan2,3, XUE Jian2, YU Haihui1, JIANG Zhiwei2, TANG Tao2,3
BI Xiang1, LI Minggang2, LU Min1, YOU Jiangan2,3, XUE Jian2, YU Haihui1, JIANG Zhiwei2, TANG Tao2,3
摘要: In the preparation process of crosslinked polyvinyl chloride (c-PVC) foam by isocyanate, the formulated mixture is generally required to be carried out under the condition of isolated water, so as to avoid the mixing difficulties caused by the reaction between the introduced water and isocyanate. In this paper, NaHCO3 was added to the mixture to indirectly introduce water into the system, and the effects of NaHCO3 on the cell structure and curing time of c-PVC foam were investigated. The results showed that NaHCO3 not only played a role of foaming agent, but also was a good nucleating agent for cells. At the same time, the introduction of NaHCO3 held back the exudation of modified diphenylmethane-4,4'-diisocyanate (MDI) on the cell wall. The effects of NaHCO3 on the cell structure and aggregation structure of c-PVC foam were studied by thermogravimetric analysis, infrared spectroscopy and scanning electron microscopy. The results showed that decomposition of NaHCO3 occurred during the molding stage, which made small amount of MDI react with water to form polyurea, improved the compatibility of MDI with PVC and inhibited the exudation of MDI.