FTIR Spectroscopy of BHET and PU Foams The structural formulae of BHET and PUFs were showed in Schemes 1 and 2. Both compounds showed three sharp absorp- tion peaks in the IR regions of 1610–1370 cm21 due to benzene ring groups (Figure 1): two absorption peaks were appeared at 1500–1450 cm21, the other peak was showed around 1300 cm21. The absorption bands due to the AOH group showed at 3400–3230 cm21 demonstrated the completely depolymerization of PET to BHET. The absorption peak at 2275–2225 cm21 related to the ANCO group was showed in Figure 1(b). The addition polymerization of PMDI and BHET could be verified.
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