CHARACTERIZATION, PROCESSING, AND PROPERTIES OF AN AROMATIC POLY(ETHER KETONE)

Poly(oxy-1,3-phenylenecarbonyl-1,4-phenylene), mPEK, was sythesized in a methane sulfonic acid/phosphorus pentoxide medium through the polycondensation of 3-phenoxybenzoic acid. The polymer was soluble at room temperature in strong acids and common organic solvents. Differential scanning calorimetry on mPEK indicated a glass transition temperature of 132-degrees-C and no detectable crystal melting behavior. The polymer was thermo-oxidatively stable up to 420-degrees-C in air as determined by thermogravimetric analysis. Thermal degradation resulted in a crosslinked polymer. Compression molding was successfully applied to consolidate mPEK powder into bulk specimens without causin degradation. Tensil-fractured surfaces on the consolidated specimens were examined by scanning electron microscopy which strongly indicated adequate fusion of mPEK powder but also disclosed microvoids of uniform size, shape, and distribution. X-ray scattering revealed that mPEK powder was amorphous and that the consolidated mPEK specimens were structurally isotropic as well as amorphous. The bulk specimen density was determined to be 1.29 +/- 0.01 g/cm3 and the three-dimensionally isotropic bulk tensile properties were shown to be 4.10 +/- 0.10 GPa (modulus), 0.07 +/- 0.01 GPa (strength), and 0.021 +/- 0.006 (elongation at break). Tensile properties of the amorphous mPEK specimens compared favorably with literature values of state-of-the-art semicrystalline thermoplastics. Crystalline phases could be realized for mPELK by melt-processing, or precipitating from a solvent.