Spin-Trapping Analysis and Characterization of Thermal Degradation of Thermoplastic Poly(ether–ester) Elastomer

Abstract

We investigated the thermal degradation of poly(butylene terephthalate)-co-poly(ethylene oxide) (PBT-co-PEO), a thermoplastic poly(ether–ester) elastomer (TPEE), through proton nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), gel permeation chromatography (GPC), and spin-trapping electron spin resonance (ESR) analysis to detect radical intermediates present during degradation. Three kinds of PBT-co-PEO with different component ratios of PBT/PEO were synthesized. The thermal degradation process of PBT-co-PEO was divided into four weight-loss stages. In the first stage from room temperature to 120 °C, we confirmed the production of two radical intermediates, O–•CH–CH2 and •CH2–, by the spin-trapping method. This suggested that the initial decomposition occurred at the OCH2–CH2O bond in the PEO units. Upon annealing at 120 °C, PBT-co-PEO showed a small degree of random degradation, while higher PBT con...