Polymers, liquid crystalline continued

The parameter /r tunes the stiffness of the potential. It is chosen such that the repulsive part of the Leimard-Jones potential makes a crossing of bonds highly improbable (e.g., k= 30). This off-lattice model has a rather realistic equation of state and reproduces many experimental features of polymer solutions. Due to the attractive interactions the model exhibits a liquid-vapour coexistence, and an isolated chain undergoes a transition from a self-avoiding walk at high temperatures to a collapsed globule at low temperatures. Since all interactions are continuous, the model is tractable by Monte Carlo simulations as well as by molecular dynamics. Generalizations of the Leimard-Jones potential to anisotropic pair interactions are available e.g., the Gay-Beme potential [29]. This latter potential has been employed to study non-spherical particles that possibly fomi liquid crystalline phases. 

Thermotropic Liquid-Crystalline Polymers with Mesogenic Side Groups Table 5 (continued)... 

Another important application of thermoplastic fibers such as poly ether ether ketone (PEEK), Poly etherimide(PEI), and VectranM andHS (Vectranis the trade mark of Hoechst liquid crystalline polymer) is in making thermoplastic matrix composites. Commingled yams of the reinforcement and matrix such as quartz/PEEK, glass/PEI, Vectran HS/M are used to make the composites wherein the matrix yarn fuses to form the continuous phase of the composite. 

EQA/1.6-Hexanediol/1.4-Butanediol Oopolvesters. Figure 2 shows the effect of BD content cm the Tin and Ti values of BDA/HD/BD copolyesters. Modification of the BDA/HD hemopolyester with BD introduced disorder in the crystalline polymer and, consequently, the Tin s decreased until sufficient BD was present to start increasing the order as the BDA/BD hemopolyester composition was approached. The Ti values, on the other hand, increased continuously because the liquid crystalline mesophase became more stable as the six-cartoon HD component of the BDA/HD homopolyester was replaced by the less flexible four-carbon BD component. 

The homopolyestcr of 4-hydroxybcnzoic acid and its copolyestcrs with 6-hydroxy-2-naphthoic acid and with 4,4 -biphenol and tcrephthalic acid are of continuing commercial and academic interest. (1,2) From the applications side, interest stems from the high moduli and high temperature properties of these polymers, while on the fundamental side, interest arises from the main-chain thermotropic liquid crystalline... 

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