ABSTRACT
This chapter aims to clarify the industrial origins of thermotropic liquid crystalline polymers (TLCPs) in the 1970s based on the published literature, and to review the unique post-heat-strengthening capability of these materials in various forms driven by solid-phase polymerization. Main-chain TLCPs represent a class of high performance condensation polymers composed mainly of para-extended aromatic polyesters. In film form, excellent barrier properties are afforded by the dense uniaxial liquid crystalline morphology, and it is anticipated that medical and food packaging opportunities in addition to electronics will emerge rapidly coincident with lower resin costs and expanded TLCP production. Fiber heat-strengthening has been covered most extensively in a number of reviews and research investigations. Because of the ready availability of Vectra over the years, there have been many structural and mechanistic studies of the hydroxybenzoic acid/2,6-hydroxynaphthoic acid system and thus this composition has served as a useful model of TLCP behavior.
