Chemical Research in Chinese Universities ›› 2023, Vol. 39 ›› Issue (5): 782-789.doi: 10.1007/s40242-023-3067-4

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Introduction and Influence of Water in the Preparation of Crosslinked PVC Foam by Isocyanate

BI Xiang1, LI Minggang2, LU Min1, YOU Jiangan2,3, XUE Jian2, YU Haihui1, JIANG Zhiwei2, TANG Tao2,3   

  1. 1. College of Chemical Engineering, Northeast Electric Power University, Jilin 132011, P. R. China;
    2. State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China;
    3. College of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei 230026, P. R. China
  • Received:2023-03-08 Online:2023-10-01 Published:2023-09-26
  • Contact: TANG Tao, JIANG Zhiwei, YU Haihui E-mail:ttang@ciac.ac.cn;jiangzw@ciac.ac.cn;hhyu@neepu.edu.cn
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (No.52173050) and the National Key Research and Development Program of China (No.2021YFB3702800).

Abstract: 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.

Key words: Crosslinked PVC foam, Isocyanate, Water, Curing, Sodium bicarbonate