Влияние гамма-облучения на фазовые переходы в политетрафторэтилене, допированном диоксидом кремния растительного происхождения

Abstract The effect of gamma irradiation and doping with silicon dioxide on the first-order solid-state phase transition in polytetrafluoroethylene is studied by the differential scanning calorimetry method. A quantitative analysis of the profiles of the heat capacity peaks is carried out on the basis of the theory of diffuse phase transitions. It is shown that the elementary volume of the phase transformation depends on the γ irradiation and the concentration of silicon dioxide.

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Phase Transitions by Dilatometry, Part I: Synthesis, Characterisation and Isotropic to Smectic-A and Smectic-A to Smectic-B Transitions in Two Liquid Crystalline Higher Homologues of N-(p-n-nonyloxybenzylidene) p-n-alkylanilines

Zeitschrift für Naturforschung A ◽

10.1515/zna-2004-0902 ◽

2004 ◽

Vol 59 (9) ◽

pp. 537-542 ◽

Cited By ~ 1

Author(s):

C. Rama Chandra Prabhu ◽

S. Lakshminarayana ◽

V. G. K. M. Pisipatia

Keyword(s):

Phase Transition ◽

Differential Scanning Calorimetry ◽

Transition Temperature ◽

Liquid Crystalline ◽

Scanning Calorimetry ◽

First Order ◽

Smectic A ◽

M 12 ◽

Phase Variants ◽

Enthalpy Data

Two higher homologues of N(p-n-nonyloxybenzylidene)p-n-alkylanilines, viz. the 9O.m series with m = 12 and 16, are synthesised and characterised by thermal microscopy, differential scanning calorimetry and density studies. The compounds exhibit the phase variants smectic-A, smectic-B and smectic-G. Density studies reveal the first order nature of the isotropic to smectic-A and smectic-A to smectic-B transitions. An estimate of the pressure dependence of the phase transition temperature, using volume and enthalpy data, is presented. A comparison of these results with those reported on nO.m and other liquid crystalline compounds is presented.

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Phase Transition Studies across Isotropic-Smectic A and Smectic A-Smectic F Phases in 90.4

Zeitschrift für Naturforschung A ◽

10.1515/zna-1989-0106 ◽

1989 ◽

Vol 44 (1) ◽

pp. 23-25

Author(s):

D. M. Potukuchi ◽

P. Bhaskara Rao ◽

N. V. S. Rao ◽

V.G. K. M. Pisipati

Keyword(s):

Phase Transition ◽

Differential Scanning Calorimetry ◽

Thermal Expansion ◽

Phase Transitions ◽

Pressure Dependence ◽

Scanning Calorimetry ◽

First Order ◽

Smectic A ◽

Density Results ◽

Transition Studies

Abstract The temperature dependence of the density of N(p-n-nonyloxy benzylidene)p-n-butylaniline (90.4) is studied. The compound exhibits smectic A, smectic F and smetic G phases. The isotropicsmectic A (IA) and smetic A-smectic F phase transitions are found to be first order. The calculated thermal expansion coefficient and differential scanning calorimetry support the density results. The density jumps, associated enthalpies and the estimated pressure dependence of the transition temperatures for IA transitions in other compounds are also presented.

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Heat Capacity of the Rb3LnCl6 Compounds with Ln = La, Ce, Pr, Nd

Zeitschrift für Naturforschung A ◽

10.1515/zna-1999-6-709 ◽

1999 ◽

Vol 54 (6-7) ◽

pp. 397-403 ◽

Cited By ~ 1

Author(s):

L. Rycerz ◽

M. Gaune-Escard

Keyword(s):

Experimental Data ◽

Phase Transition ◽

Differential Scanning Calorimetry ◽

Heat Capacity ◽

Liquid Phase ◽

Formation Enthalpy ◽

Heat Capacities ◽

Small Decrease ◽

Scanning Calorimetry ◽

Increasing Temperature

Abstract The heat capacities of the solid and liquid Rb3LnCl6 compounds, where Ln = La, Ce, Pr, Nd, have been determined by differential scanning calorimetry (DSC) in the temperature range 300 -1100 K. The heat capacity shows a small decrease with increasing temperature from the temperature of phase transition up to 150 -200 K above this transition for the Rb3CeCl6, Rb3PrCl6 and Rb3NdCl6 compounds. The measured heat capacities were used to calculate the formation enthalpy of the liquid phase. The results obtained compare satisfactorily with the known experimental data.

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Heat Capacity of K3LnCl6 Compounds with Ln = La, Ce, Pr, Nd

Zeitschrift für Naturforschung A ◽

10.1515/zna-1999-3-412 ◽

1999 ◽

Vol 54 (3-4) ◽

pp. 229-235 ◽

Cited By ~ 2

Author(s):

M. Gaune-Escard ◽

L. Rycerz

Keyword(s):

Experimental Data ◽

Phase Transition ◽

Differential Scanning Calorimetry ◽

Heat Capacity ◽

Phase Transitions ◽

Liquid Phase ◽

Temperature Dependence ◽

Heat Capacities ◽

Scanning Calorimetry ◽

The Enthalpy Of Formation

The heat capacities of the solid and liquid K3LnCl6 compounds (Ln = La, Ce, Pr, Nd) have been determined by differential scanning calorimetry (DSC) in the temperature range 300 -1100 K. Their temperature dependence is discussed in terms of the phase transitions of these compounds as reported in literature. The heat capacity increases and decreases strongly in the vicinity of a phase transition but else varies smoothly. The Cp data were fitted by an equation which provides a satisfactory representation up to the temperatures of Cp discontinuity. The measured heat capacities were checked for consistency by calculating the enthalpy of formation of the liquid phase, which had been previously measured. The results obtained compare satisfactorily with these experimental data.

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Thermodynamic Properties of EuCl2 and the NaCl-EuCl2 System

Zeitschrift für Naturforschung A ◽

10.1515/zna-2001-0907 ◽

2001 ◽

Vol 56 (9-10) ◽

pp. 647-652 ◽

Cited By ~ 10

Author(s):

F. Da Silva ◽

L. Rycerz ◽

M. Gaune-Escard

Keyword(s):

Phase Transition ◽

Phase Diagram ◽

Differential Scanning Calorimetry ◽

Heat Capacity ◽

Thermodynamic Properties ◽

Linear Equation ◽

Scanning Calorimetry ◽

Temperature Range

Abstract The temperature and enthalpy of the phase transition and fusion of EuCl2 were determined and found to be 1014 K, 11.5 kJ mol-1and 1125 K, 18.7 kJ mol-1 , respectively. Addition ally, the heat capacity of solid EuCl2 was measured by Differential Scanning Calorimetry in the temperature range 306 -1085 K. The results were fitted to the linear equation C0p,m = (68.27 + 0.0255 T/K) J mol -1 K-1 in the temperature range 306 -900 K. Due to discrepancies in the liter ature on the temperature of fusion of EuCl2, the determination of the NaCl-EuCl2 phase diagram was repeated. It consists of a simple eutectic equilibrium at Teut = 847 K with x(EuCl2) = 0.49.

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