| Abstract: | In this work, fluorine‐containing copolyimides were synthesized from 6FDA dianhydride and different ratios of BisAAF and PPD diamines. Properties, such as composition, viscosity, dielectric constant, glass‐transition temperature, thermal decomposition temperature, tensile characteristics, and transmittance, were investigated by using elemental analysis, viscometry, Fourier transform infrared spectrometry, differential scanning calorimetry, a thermogravimetric analyzer, a tensile tester, and UV–visible spectrophotometry. After curing at 300°C for 1 h, imidization was observed, as indicated the appearance of an absorption peak of the carbonyl of the imide at 1780 cm?1 (C?O asymmetry stretching). The inherent viscosity increased with an increasing PPD mole fraction, from 0.40 dL/g of pure 6FDA‐BisAAF to 0.84 dL/g of pure 6FDA‐PPD. The dielectric constant decreased with increasing fluorine content. The glass‐transition temperature increased with an increasing PPD mole fraction; the values increased from 317°C with pure 6FDA‐BisAAF polyimide to 364°C with pure 6FDA‐PPD polyimide. The 5% weight loss temperature (Td) of the copolyimides was around 530°C in air and 540°C in a nitrogen atmosphere. The tensile modulus and tensile strength gradually increased with an increasing PPD molar fraction. The transmittance of 6FDA‐BisAAF‐PPD copolyimides was greater than 90% at wavelengths above 500 nm. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2064–2069, 2005 |
