Compatibility and properties of alternating ethylene-tetrafluoroethylene copolymer and poly(methyl methacrylate) blends

Blends of an alternating ethylene-tetrafluorethylene copolymer (ETFE) and poly(methyl methacrylate) (PMMA) were prepared by melt mixing in a mixer. Compatibility, thermal behaviour and morphology of the blends of various compositions were investigated by using dynamic mechanical analysis (d.m.a.), Fourier transform infrared spectroscopy (FTi.r.), solid-state nuclear magnetic resonance (n.m.r.) spectroscopy, differential scanning calorimetry (d.s.c.) and wide-angle X-ray diffraction. D.m.a. and d.s.c. results show that the glass transition temperature (T-g) of the ETFE in the blends increases as the PMMA content increases and the T-g of the PMMA moves to low temperatures when the ETFE content increases. In addition, d.s.c. results indicate an additional T-g, which is located between the T-g of PMMA and that of ETFE. The presence of this additional T-g suggests the existence of one semicrystalline phase and two amorphous phases-an ETFE/PMMA phase and a PMMA-rich phase. D.s.c. results also indicate that the melting temperature of ETFE decreases while the crystallinity of ETFE increases slightly as the PMMA content increases. FTi.r. results show that the absorption peak of the carbonyl group of the PMMA in the blends stays almost at the same position as in the pure component. Solid-state n.m.r. results reveal that the changes in chemical shift of the carbonyl group of PMMA in the blends are less than 0.5 ppm. These results confirm that only weak interactions exist between ETFE and PMMA. X-ray diffraction results reveal that no new crystal forms appear in the blends. (C) 1997 Elsevier Science Ltd.