Liquid crystal polymers polymorphism

Liquid crystal display technology, 15 113 Liquid crystalline cellulose, 5 384-386 cellulose esters, 5 418 Liquid crystalline conducting polymers (LCCPs), 7 523-524 Liquid crystalline compounds, 15 118 central linkages found in, 15 103 Liquid crystalline materials, 15 81-120 applications of, 15 113-117 availability and safety of, 15 118 in biological systems, 15 111-113 blue phases of, 15 96 bond orientational order of, 15 85 columnar phase of, 15 96 lyotropic liquid crystals, 15 98-101 orientational distribution function and order parameter of, 15 82-85 polymer liquid crystals, 15 107-111 polymorphism in, 15 101-102 positional distribution function and order parameter of, 15 85 structure-property relations in,... 

Polarized analysis There is useful spectral information arising from the analysis of polarization of Raman scattered light. This, typically called as polarized analysis, provides an insight into molecular orientation, molecular shape, and vibrational symmetry. One can also calculate the depolarization ratio. Overall, this technique enables correlation between group theory, symmetry, Raman activity, and peaks in the corresponding Raman spectra. It has been applied successful for solving problems in synthetic chemistry understanding macromolecular orientation in crystal lattices, liquid crystals or polymer samples and in polymorph analysis. 

FIGURE 15.20 Gibbs free energy G versus temperature T for liquid and various crystal forms of triglycerides, (a) General trend for the main polymorphs, (b) Observed trends for SOS. (Results taken from K. Sato. Progr. Colloid Polym. Sci. 108 (1988) 58.)... 

Sun Y, Xi H, Ediger MD, Richert R, Yu L (2009) Diffusion-Controlled and Diffusionless Crystal Growth near the Glass Transition Temperature Relation between Liquid Dynamics and Growth Kinetics of Seven ROY Polymorphs. J Chem Phys, pp 131 Sun Y, Tao J et al (2010) Solubilities of crystalline drugs in polymers an improved analytical method and comparison of solubilities of indomethacin and nifedipine in PVP, PVP/VA, and PVAc. J Pharm Sci 99(9) 4023-4031... 

Polymer compounds often contain curatives or crosslinking agents. This is especially true for rubber compounds. The most important curatives are sulfur and sulfur compoimds. Elementary sulfur exists in a number of aUotropic forms [ 55 ]. Ordinary sulfur is a yellow solid substance, which forms crystals with orthorhombic symmetry. It is called orthorhombic (or rhombic, a-) sulfur. At 112.8 °C orthorhombic sulfur melts to form a straw-colored liquid, which consists of staggered ring Sg molecules and has a low viscosity. If this melt is cooled down, it crystallizes into a second polymorphic form monoclinic sulfur (y-sulfur). Orthorhombic sulfur (a-sulfur) is the most stable form at low temperatures, but above 95.5 C the most stable form is monoclinic sulfur (P-sulfur), which is stable between 94.5 and 120 C. This melts at 120 °C to form an Sg straw-colored melt. When molten sulfur is heated, it becomes more viscous because of its polymerization. It becomes darker in color and turns red. 

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