Polymer Liquid Crystals (PLCs) Alloys and Blends

Laboratory of Polymers and Composites
Department of Materials Science
University of North Texas
Denton, TX 76203-5308


ABSTRACT

Polymer Liquid Crystals (PLCs) show superior properties over conventional thermoplastic polymers with regard to chemical resistance, low flammability and high modulus.1 In addition, their low isobaric expansivity combined with their low viscosities at processing temperatures combine to assist in the development of high tolerance parts. PLCs achieve these properties due to their unusual phase behavior during temperature variations. In conventional semi-crystalline thermoplastics, three kinds of relaxational phenomena are seen:

Since PLCs have additional phase behavior due to their mesophases, understanding their phase behavior is vital to their use. In the past we reported on the mechanical behavior and phase diagram of the transition temperatures versus the mole fraxtion x of a series of PET/xPHB PLCs, where PET = poly(ethylene terephthalate) and PHB = p-hydroxybenzoic acid.2 To study the effects of blending PLCs with cheaper thermoplastics in order to obtain higher strength plastics at a lower cost, we continue to study systems of the engineering plastics (EP) + PLC type.3-5 Rheological experiments show that EP viscosity decreases upon addition of a PLC, making processing easier while reinforcing the EP at the same time.5


1. W. Brostow, Polymer, 1990, 31, 979.
2. W. Brostow, M. Hess, B.L. López, Macromolecules, 1994, 27, 2262.
3. W. Brostow, M. Hess, B.L. López and T. Sterzynski, Polymer, 1996, 37, 1551.
4. W. Brostow, B.L. López and T. Sterzynski, in preparation.
5. W. Brostow, T. Sterzynski and S. Triouleyre, Polymer, 1996, 37, 1561.



Maintained by Dr. Antje Stein de Vilchez.