Temperature evolution of liquid-crystalline

Temperature Evolution of the Structure of Liquid-Crystalline Main-Chain Copofyesters... 

Lewis Acid Complexes. Sulfolane complexes with Lewis acids, such as boron trifluoride or phosphorus pentafluoride (17). For example, at room temperature, sulfolane and boron trifluoride combine in a 1 1 mole ratio with the evolution of heat to give a white, hygroscopic solid which melts at 37°C. The reaction of sulfolane with methyl fluoride and antimony pentafluoride in liquid sulfur dioxide gives crystalline tetrahydro-l-methoxythiophenium-1-oxidehexafluoroantimonate, the first example of an alkoxysulfoxonium salt (18). 

The residue from Experiment Mo. 9 may be used, or the compound may be prepared independently as follows Twenty grains of arsenic trioxide are treated dropwise with 2ttml of concentrated nitric add under the hood and the mixture is heated on the steam bath until the evolution of nitrogen oxides is complete. The liquid is decanted from any undissolved made and evaporated just to dryness over a very small flame. The residue is dissolved in 75ml of hot water and filtered by suction if necessary. A thermometer is placed in the filtrate and the latter is evaporated until the viscous liquid has reached a temperature of 130° C. The vessel and contents are transferred to a vacuum desiccator which is placed in the refrigerator an almost solid mass of white crystalline product is obtained. 

Thirty grams of sodium. pentacyanonitrosylferrate (II) 2-hydrate (No. 74) are covered with 120ml of ice-cold water in a 250ml suction flask with a gas-inlet tube and a thermometer. The flask is cooled in an ice-salt bath while a steady stream of ammonia (3 bubbles/sec) is led in under the hood. Csre must be taken that the temperature does not rise above 20°C during this time because decomposition would occur the optimum range is 8-12°C. When no more gas is absorbed at this temperature, (indicated when the level of the liquid fails to rise in the inlet tube as the current of gas is interrupted), the dark yellow-brown solution is allowed to stand at 0°C for about 2 days. The amber-colored crystalline product separates with attendant evolution of gas,... 

Figure 3 Transitiometric investigation of the pressure effect on the isobaric thermal expansivities a. of gaseous, liquid, and solid substances (a) comparison between calculated ana experimental data of methane at 333 K (bl) quinoline as a simple fluid (b2) water as the associated liquid (cl) effect of temperature on medium-density polyethylene (MDPE) (c2) evolution of with the crystallinity (points represent the experimental data and the lines were obtained by the least squares fitting of data) (c3) comparison between the experimental a for three polyethylenes with different degrees of crystallinity and the predicted values for crystal and amorphous phases obtained by extrapolation from linear fitting of the experimental data...

While the IR dichroism and NMR studies can give information about the conformation at individual bonds, the small-angle neutron scattering (SANS) measures the global conformation of the polymers (Cotton et al., 1974). SANS has been successfully utilized, for example by Hardouin and coworkers (Hardouin et al, 1991 Leroux et al, 1993), to establish the evolution with the temperature of the global shape of some mesogen-jacketed liquid crystalline polymers from isotropic to the nematic phase. A pseudobinary system of fully protonated polymer (P4,4,4) with the same polymer... 

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