Thermal degradation during melt processing of poly(ethylene oxide), poly(vinylidenefluoride-co-hexafluoropropylene) and their blends in the presence of additives, for conducting applications

In this paper, the thermal degradation during compounding of poly(ethylene oxide) and poly(vinylidenefluoride-co-hexafluoropropylene) and their immiscible blends was investigated. Infrared spectroscopy, size exclusion chromatography, dynamic rheology, thermogravimetric analysis, and coupled gas chromatography-mass spectroscopy were used. Most of the identified degradation products or substances are glycols, formates, lactones, ethers or even acids for long processing times. The mechanisms for the production of these chemical compounds were already reported in previous publications. Additionally, the influence of carbon black and LiV₃O₈ additives, currently used for enhancing the conductive properties, was studied. Addition of carbon black causes an increase in the PEO stability, whereas addition of LiV₃O₈ has an opposite and dramatic effect. PVDF-HFP is found to be less susceptible to degradation because of the inherent stability of fluorine-containing polymers. However, melt processing provides additional contributions to degradation because of the high viscosities.