Isoconversional Glass Transition Kinetics and Fragility Determination of Poly[(ethylene 2,6-naphthalate)-co-(butylene 2,6-naphthalate)] Random Copolymers

Isoconversional methods were applied to DSC data to determine the effective activation energy, DE, for the glass transition in a series of PEBN random copolymers. It was revealed that DE varies rather significantly throughout the process, decreasing with temperature as well as with the amount of BN units in the copolymer chain. Moreover, the dynamic fragility, m, of PEBN copolymers was evaluated. Employing the scanning rate dependency of T-g it was found that as the amount of BN units in the copolymer increases, m gets lower values denoting more strong materials, while the inverse was concluded by applying the extrapolation of configurational entropy to zero method. Results of the later method were verified by tensile mechanical property measurements of the copolymers.