BLENDS OF THE ALTERNATING ETHYLENE-TETRAFLUOROETHYLENE COPOLYMER WITHPOLY(VINYLIDENE FLUORIDE)

Blends of the alternating ethylene-tetrafluoroethylene copolymer (ETFE ) with poly(vinylidene fluoride) (PVF2) were prepared by melt-mixing. Compatibility, morphology, thermal behavior, and mechanical properties of the ETFE/PVF2 blends with various compositions were studied by usi ng differential scanning calorimetry (DSC), wide-angle X-ray diffracti on (WAXD), dynamic mechanical analysis (DMA), thermogravimetric analys is (TGA), tensile tests, and scanning electron microscopy (SEM). DMA s tudies showed that the blends have separate glass transition temperatu res (T-g) close to those of the pure polymers. ETFE and PVF2 are incom patible. Marked negative deviations from simple additivity were observ ed for both the ultimate strength and the elongation at break over the entire composition range. The interfaces between ETFE and PVF2 are we akly bonded with rather poor interaction. SEM observations revealed th at the blends have a two-phase structure and the adhesion between the phases is poor. (C) 1997 John Wiley & Sons, Inc.