Structure and properties of fluorinated polymer/poly(ethylene oxide) blends

BACKGROUND: In order to explore ways for improving the toughness of copolymers of vinylidene difluoride and chlorotrifluoroethylene (P(VDF-CTFE)), polyethylene oxide (PEO) with ultrahigh molecular weight and good mechanical properties was applied for the first time to prepare P(VDF-CTFE)/PEO blends for adhesives applications. RESULTS: The results show that with an increase of PEO content, the mechanical properties of the blends are improved markedly, and blends with high strength, modulus and toughness are obtained. The difference in the solubility parameters of P(VDF-CTFE) and PEO is small, and only a single a-relaxation peak is observed in the high-temperature zone for the blends, indicating that the blend system is partially miscible. The experimental values for the glass transition temperature of the blend varying with PEO content are always higher than those predicted by the Fox equation, and a strong interaction is supposed to occur between the molecules of P(VDF-CTFE) and PEO. The relative crystallinity of the blends increases with PEO content, and the PEO particles disperse homogeneously in the P(VDF-CTFE) matrix, whose average size decreases with increasing PEO content. Phase-inverted morphologies of the blends are observed above 60 wt% of PEO. CONCLUSION: The partial miscibility of P(VDF-CTFE)/PEO blends leads to an improvement of the mechanical properties of the blends, which is an effective way to improve the toughness of fluorinated polymers. (C) 2009 Society of Chemical Industry