Pitch biphenyls

Plate 7. Pitch bands associated with the TGBA phase at a temperature near to the clearing point of (S)-l-methylheptyl 4 -(4-n-tetradecyloxyphenylpropioloyloxy)biphenyl-4-carbox-ylate (xlOO)... 

As shown in Figure 2.2, the condensation of borazine results in a mixture of biphenyl and naphthalene analogs in addition to larger planar units. Like graphitizable pitch, these appear to have the potential to stack in a discotic phase allowing for formation of a graphitic boron... 

In another paper [15], these authors have prepared the first inorganic mesophase by low-temperature thermolysis of the borazine. Following the synthesis procedure reported by Sneddon etal. [11-13] (Eq. 14.1), the prediction made on the formation of biphenyl and naphtalen-type units and requirements for the formation of pitch mesophases [16], the authors have modified the thermolysis rate to maintain a certain mobility in as-formed molecules, and therefore obtain optically anisotropic phases during thermolysis of borazine. The formation of a liquid-crystalline phase during thermolysis provides an efficient way to produce a final BN material with a high degree of crystalline order by heating to 1800 °C. 

The predicted phase sequence SmA-TGBA-N was first observed in a mixture of cholesteryl nonanoate and nonyloxybenzoic acid [59], later in a chiral derivative of 4-biphenyl-benzoate [7] and many other pure compounds. According to the theoretical predictions, the occurrence of TGB phases requires a high optical purity and the abilities of the molecules to form a small cholesteric pitch as well as a smectic layer structure. The phase diagrams of chiral-racemic mixtures (Figure 10.8) confirm that the TGB... 

Carbonaceous materials are obtained via heat treatment from various sources, including coal, liquefied coal, coke, petroleum, resins, carbon blacks, paraffins, olefins, pitch, tar, polycyclic aromatic compounds (naphthalene, biphenyl, naphthalene sulfonic acid, anthracene sulfonic acid, phenanthrene sulfonic acid, etc.), polymers (polyethylene, polymethylacrylale, polyvinyl chloride, phenol resin, polyacrylonitrile, etc.) [99-101J. This kind of fluids is claimed to. show a strong ER effect, low electric power consumption and excellent durability [101]. Several publications addressed the ER effect and physical properties of carbonaceous ER fluids [102-104]. 

Table 7. Comparison of the spontaneous polarization (extrapolated to 100%), response times (10 Vpp/pm square wave, time to maximum current), pitch and tilt angle measured at 25°C for mixtures of 7 wt% 4-octyloxy-l,r-biphenyl-4 -yl (/ )-2-fluorohexanoate and 7 wt% trans- 4-(4-octyloxyphenyl)cyclohexyl (/f)-2-fluorohexanoate and a host mixture [69].

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