SYNTHESIS AND MOLECULAR CHARACTERIZATION OF NARROW MOLECULAR-WEIGHT DISTRIBUTION FRACTIONS OF METHYL-SUBSTITUTED POLY(ARYL ETHER ETHER KETONE)

Poly(aryl ether ether ketone) (PEEK) is a high-performance polymer. However, it is difficult to study the properties of PEEK because it has a high tendency to crystallize and is only soluble in strong acids at room temperature. Furthermore, the viscoelastic properties of the amorphous melt cannot be studied in the important T(g) < T < T(g) + 175-degrees-C temperature range. Therefore, methyl-substituted poly(aryl ether ether ketone) (MePEEK) has been studied as a replacement for PEEK. The polymer has been fractionated and the fractions have been characterized by light scattering and intrinsic viscosity measurements in NMP and methanesulfonic acid. The results indicate that MePEEK is a freely rotating polymer with the characteristic ratio of C(infinity) = 2.44. The molecular weight dependence of the glass transition temperature is established. The viscoelastic properties of the melts have been measured between 170 and 250-degrees-C. The molecular weight between entanglements, M(e) = 1450, has been calculated from the plateau modulus and is related to the molecular characteristics of the aryl-ether-ether-ketone chain.