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

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.

Keywords

Crosslinked PVC foam / Isocyanate / Water / Curing / Sodium bicarbonate

References

[1] Yao H, Pang Y, Liu X, Qu J. Polymers, 2022, 14: 3522.

[2] Juliyana M, Krishnan R S. Mater. Res. Express, 2018, 5(2): 025307.

[3] Bull P H, Edgren F. Compos. Part B: Eng., 2004, 35(6–8): 535.

[4] Veazie D R, Robinson K R, Shivakumar K. Compos Part B: Eng., 2004, 35(6–8): 461.

[5] Sadler R L, Sharpe M, Panduranga R, Shivakumar K. Compos. Struct, 2009, 90: 300.

[6] Belingardi G, Cavatorta M P, Duella R. Compos. Struct., 2003, 61(1/2): 13.

[7] Luong D D, Pinisetty D, Gupta N. Compos. Part B: Eng., 2013, 44(1): 403.

[8] Amelia J J N, Zuhri M Y M, Leman Z, Zahari N I, As’arry A, Ilyas R A. Polymers, 2021, 13: 3603.

[9] Atas C, Sevim C. Compos. Struct., 2010, 93(1): 40.

[10] Chang H, Abu-Zahra N. J. Vinyl Addit. Techn., 2011, 17(1): 17.

[11] Petchwattana N, Covavisaruch S, Pitidhammabhorn D. J. Polym. Res., 2013, 20: 172.

[12] You J A, Xing H P, Xue J, Jiang Z W, Tang T. Compos. Sci. Technol., 2021, 203: 108566.

[13] Jiang Z W, Du Z H, Xue J, Liu W B, Li M G, Tang T. JAPS, 2018, 135: 46141.

[14] Landler Y. J. Cell. Plast, 1967, 3: 400.

[15] Jiang Z W, Yao K, Du Z H, Xue J, Tang T, Liu W B. JAPS, 2014, 131(15): 40567.

[16] Shi A H, Zhang G C, Zhao C H. Molecules, 2012, 17(12): 14858.

[17] You J A, Xue J, Jiang Z W, Tang T. Adv. Eng. Mater., 2021, 24: 2100858.

[18] You J A, Jiang Z W, Jiang H Q, Qiu J, Li M G, Xing H P, Xue J, Tang T. Chem. Eng. J., 2022, 450: 138071.

[19] Ma M F, Pang X Y, Chang R. Int. Polym. Proc., 2019, 34(2): 239.

[20] Li J W, Wang H Y, Zhou H F, Jiang J, Wang X F, Li Q. ACS Omega, 2021, 6(35): 22672.

[21] Chandran R, Tohit E R M, Stanslas J, Mahmood T M T, Salim N. J. Drug Deliv. Sci. Tec., 2022, 68: 103080.

[22] Song M, Choi K, Choi I, Han S K, Ryu Y H, Oh D H, Ahn G Y, Choi S W. Macromol. Rapid Commun., 2022, 43: 220042.

[23] Li M G, Qiu J, Xing H P, Fan D L, Wang S, Li S X, Jiang Z W, Tang T. Polymer, 2018, 155: 116.