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This paper studied the effects of the superheating degree and cooling intensity on the solidification structure of CP 780 slab. The results indicated that the equiaxed crystal ratio decreases with the increase of superheating degree and the cooling intensity. When the superheating degree increases from 15 to 25°C, the equiaxed crystal ratio drops sharply. While the equiaxed crystal ratio decreases slightly with an increasing superheating degree from 25°C to 55°C. It is further revealed that the superheating degree has a greater effect on the equiaxed crystal ratio compared with the influence of cooling intensity. Quantitative analysed the relationship among the equiaxed crystal ratio, the superheating degree and cooling intensity is in line with the Extreme 2D model. The accuracy of the model performance can reach 97.6% when predicting the equiaxed crystal ratio of CSP-CP 780 during CSP process. [ABSTRACT FROM AUTHOR]

Eight series of fluorosubstituted three-ring ester liquid crystals have been synthesized. Polarizing microscopic textural observations and DSC measurements of their phase transitions show that most are thermotropic liquid crystals with nematic and smectic A phases; furthermore, several show monotropic high order smectic phases. The results showed that the SmA phase is enhanced with the increasing number of fluoro-substituents at the para- and meta-positions of the terminal phenyl groups. The mesomorphic properties of these compounds are also affected by the direction of the ester bonds. The effect of the triple bond is also discussed. [ABSTRACT FROM AUTHOR]

Three homologous series of 4-(n-polyfluoroalkoxycarbonyl)phenyl 4-[(4-n-alkoxyphenyl)ethynyl] benzoates have been synthesized from 1,1,3-trihydroperfluoropropanol, 1,1,5-trihydroperfluoropentanol and 1,1,7-trihydroperfluoroheptanol. Polarizing microscopic textural observations and DSC measurements of the phase transitions of these compounds show that most of them are thermotropic liquid crystals with smectic A and very broad smectic C phases; furthermore, several show very narrow monotropic SmB phases. The effect of the terminal polyfluoroalkoxy and alkoxy groups on the mesomorphic behaviour is also discussed. [ABSTRACT FROM AUTHOR]

A family of 4-(1,1,7-trihydroperfluoroheptyloxycarbonyl)phenyl 4'-n-alkoxybiphenyl-4-car- boxylates has been synthesized. The compounds show the smectic A phase while the mesogens with intermediate terminal alkyl chain ( n 7-12) also exhibit a broad smectic C phase. [ABSTRACT FROM AUTHOR]

Several molecules having long semi-fluoroalkyl chains have been synthesized, and their phase transition temperatures measured by texture observation in a polarizing microscope and DSC. The SmC phase is particularly favoured in this series, especially for compounds with a long semi-fluoroalkyl chain. It was found that when the terminal hydrogen atom of the semifluoroalkyl chain of one of the compounds (D) was substituted by a chlorine atom, the liquid crystalline sequence and ranges did not change; however, the clearing and melting points and T[sub I-SmA] and T[sub SmA-SmC] increased by nearly 10°C. [ABSTRACT FROM AUTHOR]

Two chiral molecules, each having a long fluoroalkylalkoxy chain, have been synthesized. Their phase transition temperatures have been measured by texture observation in a polarizing microscope and confirmed by differential scanning calorimetry. Very broad SmC* phase is found in one of these two compounds. [ABSTRACT FROM AUTHOR]

Six compounds with semi-fluorinated chains have been synthesized. When the terminal hydrogen atom in the semi-fluoroalkoxy chain was changed to chlorine, both the clearing point and the melting point were enhanced. It was also found that the clearing points were decreased and melting points increased with the introduction of a triple bond into the cores. [ABSTRACT FROM AUTHOR]

A theoretical rod model for investigating the polyacrylonitrile (PAN) copolymer coagulation process was presented in this work. The mass transfer rate and coagulation rate under different coagulation conditions were obtained using this method. An optical microscope with image transfer software was employed to observe the coagulation boundary of the filament. The results showed that the coagulation rate decreased continuously with the increase of bath concentration. However, with the increase of the bath concentration, the mass transfer rate decreased at the beginning of the coagulation, and as the t1/2 increased, the weight loss was greater when the bath concentration was higher. Moreover, the coagulation rate and mass transfer rate increased with the increase of the coagulation temperature, and the coagulation was most moderate when the bath temperature was 50°C. [ABSTRACT FROM AUTHOR]

Polyacrylonitrile nascent fibers, as spun into the coagulation bath, were prepared by solution polymerization and wet-spinning, and a dimethyl sulphoxide (DMSO)/H2O coagulation bath system was adopted. The effect of coagulation bath DMSO concentration on the structure and properties of the nascent fibers was studied in detail, and the diffusion coefficients of DMSO and H2O for different bath DMSO concentrations were calculated by Crank's equation to explain the structural changes of the nascent fibers, including cross-section, core/shell structure, and surface morphology. The surface morphology of nascent fibers was observed by field emission scanning electron microscopy (FESEM). The results showed that as the coagulation bath DMSO concentration increased, the diffusion coefficients gradually decreased. More circular cross-section, less core/shell structure, higher degree of crystallinity, larger crystal size, larger bulk density, and higher sound velocity of the nascent fibers were obtained when thecoagulation bath DMSO concentration was 70 wt% compared to lower or higher bath DMSO concentration. Moreover, compared with the nascent fibers spun in other bath DMSO concentrations, smoother surfaces of the nascent fibers were obtained at the bath DMSO concentration of 70 wt%. [ABSTRACT FROM AUTHOR]

A correction to the article ""A Novel for Investigating the Structural Uniformity of Polyacrylonitrile Nascent Fibers," is presented.