Elastomers and Composites

The Rubber Society of Korea (한국고무학회)
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Effect of the Diisocyanate Type on the Hydrolysis Behavior of Polyurethane

  • Dong-Eun Kim (Department of Chemical Engineering, Dong-A University) ;
  • Seung-Ho Kang (Department of Chemical Engineering, Dong-A University) ;
  • Sang-Ho Lee (Department of Chemical Engineering, Dong-A University)
  • Received : 2023.09.11
  • Accepted : 2023.09.25
  • Published : 2023.09.30
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Abstract

The effect of diisocyanate type on the decomposition temperature of polyurethane (PU) hydrolysis was investigated in a subcritical water medium up to 250℃. PU samples were prepared using different types of diisocyanate: two aromatic diisocyanates (4,4'-methylene diphenyl diisocyanate (MDI) and methyl phenylene diisocyanate (TDI)), one unbranched aliphatic diisocyanate (hexamethylene diisocyanate (HDI)), and two cyclic aliphatic diisocyanates (4,4'-methylene dicyclohexyl diisocyanate (H12MDI) and isophorone diisocyanate (IPDI)). The pressure had no effect on hydrolysis in the range of 70-250 bar. The decomposition temperature of the PU samples increased in the following order: TDI-PU (199℃) < H12MDI ≈ IPDI ≈ HDI (218-220℃) < MDI-PU (237℃). This order of increase in temperature is related to the electron-donating ability of the group to connected to the nitrogen of the urethane unit. When the temperature of the (PU + water) mixture reached the specific decomposition temperature, the PU samples hydrolyzed completely within 5 min into primary amine and 1,4-butanediol. The hydrolysis products from MDI-PU and H12MDI-PU were separated into a liquid phase rich in (BD + water) and a solid low phase rich in amine, whereas the products from TDI-, IPDI-, and HDI-PU existed in a single aqueous phase.

Keywords

Acknowledgement

This work was supported by the Dong-A University research fund.

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