Stabilization of perfluorinated ethylene-propylene by esterification with short-chain alcohols

The perfluorinated ethylene-propylene (FEP) having unstable end groups (–COOH, –COF and –CF=CF2) were stabilized via esterification with short-chain alcohols. The effect of different alcohols on the esterification of FEP was evaluated by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis with mass spectrometry (TGA-MS). The results of IR indicated that the end-capping using methanol at 140 °C (FEP-M140) got the much better effect in converting the labile end groups of FEP into –COOCH3 group with high stability, which was further proven by TG-MS that more weight loss together with more evolved CO2 gas for FEP compared with FEP-M140 were detected. It was very visual that more bubbles caused by the evolved gas distributed in FEP than FEP-M140 films during hot processing, further confirming the end-capped FEP displayed better thermal stability than the uncapped one.