On chain entanglement in high-Tg amorphous polymers. II

Linear Viscoelastic Properties of a Poly(arylene ether ketone) with Various Molecular Weights

A new poly(arylene ether ketone) polymer (PAE) has been synthesized. This polymer was prepared from the reaction of 1, 3-bis(4-fluorobenzoyl)benzene with 2, 2-bis(4-hydroxyphenyl)propane. Dynamic rheological measurements were performed on a series of six PAE polymer melts with weight average molecular weight (Mw) ranging from 9, 600 to 113, 000 g/mole and the linear viscoelastic properties were characterized. These stiff polymers behave like thermorheological simple fluids. A WLF type of equation was found to be adequate to describe their temperature dependent properties within 100°K above the polymer glass transition temperatures, Tg's. In the regime where the chain entanglement effects predominate, the dependence of zero shear viscosity on the Mw, M%ôMwB with β=5.13, was noted to be stronger than normally observed for polymers with flexible chains. The rate dependent viscosities for samples with different Mw can be superimposed to form a master curve by shifting along the reduced frequency axis. The shift factors are shown to be described by Graessley's theory based on molecular chain entanglements.

Chain Dimensions and Rheology of Poly(arylene ethers)

Dilute solution and melt viscosities of two poly(arylene ether ketones) were compared. One polymer contained all para linkages in the backbone and the other contained one meta linkage per repeat unit. Molecular dimensions were shown to agree with calculated values and entanglement spacings could be predicted using the semi-empirical formula of Graessley and Edwards. Frictional properties in the two melts differed considerably when compared in ‘corresponding states' at Tg+100°C.