Design of Mechanically Robust High-Tg Polymers: Mechanical Properties of Glassy Poly(ester carbonate)s with Cyclohexylene Rings in the Backbone

Abstract

The incorporation of trans cyclohexylene (C-ring) groups into the main chain glassy polymers has been found to increase chain motion. With the increase in trans C-ring content, Young's modulus and yield stress both decrease. A linear correlation among Young's modulus, yield stress, and the inverse of the coefficient of thermal expansion has been found in this work. With the increase in trans C-ring content, post-yield stress drop (PYSD) decreases, the tendency to necking in tensile test decreases, and the activation volume increases. The results are consistent with the idea that thermal expansion, Young's modulus, and yield stress are predominantly controlled by intermolecular forces. Necking and PYSD are related not only to chain stiffness but also closely to polymer chain motion. On the basis of the results, the hypothesis that the incorporation of trans C-ring enhances local segmental motions, which effectively modulates interchain interactions, is proposed.