Thermal, oxidative and radiation stability of polyimides. Part IV: Polyimides based on N-[4-benzoyl-2-(2,5-dioxo-2,5-dihydro-pyrrol-1-yl)-phenyl]-acetamide and different diamines

Synthesis and properties of a novel high-temperature diphenyl sulfone-based phthalonitrile polymer

A novel high-temperature diphenyl sulfone-based phthalonitrile polymer is prepared from bis-[4-(3,4-dicyanophenoxy)phenyl]sulfone (BDS) monomer synthesized with high yield by a simple nucleophilic displacement of a nitro-substituent from 4-nitrophthalonitrile (NPN). The structure of BDS polymer is investigated by Fourier transform infrared spectroscopy and wide-angle X-ray diffraction. Curing behavior of BDS monomer with 1,3-bis(4-aminophenoxy)benzene (APB) is recorded by differential scanning calorimetry. The properties of BDS polymer are evaluated by thermogravimetric analysis, dynamic mechanical analysis, and tensile test. The results reveal that the BDS polymer exhibits excellent thermal and thermo-oxidative stabilities, high glass temperature ( Tg = 337°C), and outstanding mechanical properties (Young’s modulus: 4.02 GPa and tensile strength: 64.16 MPa). Additionally, the BDS polymer exhibits high flame retardance and low water uptake.

Study of the thermal decomposition of some azopolyimides

The thermal decomposition of some polyimides containing pendent azobenzene groups was investigated with dynamic thermogravimetric analysis. Thermal degradation of azopolyimides took place in two or three steps. Traditional nonisothermal experiments involved linearizing an equation in some manner and fitting the resulting straight line to obtain the activation energy ( Ea). The variation in activation energy with conversion degree of these polymers, obtained from two different kinetic methods, such as Flynn–Wall–Ozawa and Friedman, were compared and discussed.