LCP and their Parameters Established in Simulations

Our simulations of the above viscoelastic nematodynamics theory require the reliable and representative rheological data for LCPs, obtained for steady and transient shear flows and relaxation. We chose literature rheological data for two commercial LCPs, Titan and Zenith 6000 [49], as well as for two model polymers, a main-chain LCP, PSHQ9, and a side-chain LCP, PI-14-5CN [53]. 

According to Ref. [49] two commercial random copolyesters. Titan and Zenith 6000, were obtained from the Eastman and DuPont Chemical companies, respectively. These LCP have very narrow time and temperature intervals between the beginning of crystal melting and the onset of polymer degradation, where the liquid crystalline phase exists. The existence of multidomains in these commercial thermotropic LCPs has not been reported, and because of short time processing, it seems to be improbable. 

Titan is a random copolyester probably composed of two random units, ethylene-terephthalate (PET) and hydroxybenzoic acid (HNA). Incorporating the PET unit in the main chain reduces the rigidity of the molecule due to the two methylene flexible spacers and in turn decreases the melting temperature of the material. On the other hand. Zenith 6000 is fidly aromatic, where kinks were introduced by combining phenol and biphenol molecules by random copolymerization. As measured by DSC, the melting temperature of Titan was between 325 and 335 °C, while for Zenith 

was between 340 and 360 °C. TGA measurements indicated that the degradation temperature Tj of Titan is 450 °C, although it has been reported in Ref. [49] that the noticeable degradation begins at considerably lower temperatures. 

A nearly monodisperse PI-14-5CN was synthesized using anionic polymerization by grafting a liquid-crystalline monomer, 6-[(4-cyano-4 -biphenyl)oxy]hexanoic acid (5CN-COOH), onto a nearly monodisperse hydroxylated polyisoprene (PI). This polymer undergoes glass transition at 45 °C and N-I transition at 102 °C. 

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