Xydar Liquid crystalline polymer

T.-S. Chung and X. Jin. Studies on the phase transition and thermal stability of Xydar and Zenite series liquid crystalline polymers. Polym. Eng. Sci., 40 (4) 841-856, 2000. 

X. Jin and T. S. Chung, Thermal decomposition behavior of main-chain thermotropic liquid crystalline polymers, Vectra A-950, B-950, and Xydar SRT-900, Journal of Applied Polymer Science, 73, 2195 (1999). 

Three commercially available thermotropic liquid crystalline polymers (TLCPs) were presented as examples in this section. They are Hoechst Celanese Vectra A950 and Vectra B950 as well as Amoco Xydar . Vectra A950 is a random copolymer of 73 mol% 4-hydroxybenzoic acid and 27 mol% 6-hydroxy-2-naphthoic acid, and Vectra B950 is a random copolyesteramide consisting of 60 mol% of 6-hydroxy-2-naphthoic acid, 20 mol% terephthalic acid, and 20 mol% p-aminophenol. Xydar is made from p-hydroxybenzoic acid, isophthalic and/or terephthalic acids, and 4,4 -biphenol. The repeating unit structures of the three LCPs are shown in Figure 6.2. 

A history of the industrial development of thermotropic polymers would not be complete without a brief review of preceding technology, that is, the discoveries and developments made in lyotropic polymers. Thus, the timeline of milestones in liquid crystalline polymers proceeds from the initial observation of small molecule liquid crystallinity to the discovery of lyotropic and thermotropic high performance polymers and on through to the recent commercialization of thermotropic polyesters with the introduction of the Vectra (Celanese Corporation) and Xydar (Dartco Manufacturing) families of engineering resins. 

The first melt-processable (later categorized as thermotropic liquid-crystalline) polymer, based on p-hydroxybenzoic acid and biphenol tereph-thalate, was reported by Steven Cottis in 1972. This polymer is now available on the market as Xydar . In 1973, the first well-characterized thermotropic polymer, a copolyester of p-hydroxybenzoic acid and ethylene terephthalate, was patented by Herbert Kuhfuss and W. Jerome Jackson (Eastman-Kodak Co., USA). They reported the discovery of liquid-crystalline behaviour in this polymer in 1976. At the beginning of the 1980s, the Celanese Company developed a family of processable thermotropic liquid crystalline polymers based on hydroxybenzoic acid and hydroxynaphthoic acid, later named Vectra . 

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