Temperature Control Modes in Thermal Analysis

Transcription

1 Netsu Sokutei Temperature Control Modes in Thermal Analysis Takeo Ozawa (Received April 4, 2001; Accepted May 1, 2001) Nowadays various temperature control modes are used in thermal analysis; i.e., isothermal run, constant rate heating and cooling, sample-controlled thermal analysis, temperature jump, rate jump, temperature modulation, repeated temperature scanning, simulation for process development and temperature control for sample thermal history. Their advantages and drawbacks are reviewed with some illustrative examples, especially for application to kinetic analysis. The combined use of these modes is recommended to elucidate whole thermal behavior. Effect of heat transfer on the observed results is discussed for temperature modulation, repeated temperature scanning and jumps, and possibility of the imaginary part of the overall reaction rate constant in complex reactions is postulated, which is thought to appear in these modes together with the heat transfer effect. thermal analysis International Confederation for Thermal Analysis and Calorimetry, ICTAC 2 CRTA; Controlled Rate Thermal Analysis Sample Controlled Thermal Analysis; SCTA SCTA 1) DSC TG X FTIR Netsu Sokutei The Japan Society of Calorimetry and Thermal Analysis. 175

2 DSCFTIR DSC a r ν / cm 1 6) DSCX X DSC 7) TG EGA 8) DSC TG 3 FTIR 2θ X 2 3 2) Fig.1 Thermophotometry results of polyimide film. 5) a) Spectrum change by heating. b) Functional group changes by heating. 5) The symbols, a, v, T and r, are respectively the absorbance, the wave number, the temperature and the ratio of peak height. 2) FTIR 3) 4) 3) Fig.1 5) FTIR 1,2) 1) 9) 10) 11) 12-14) 15) 16-19) 20) 16) 17,18) 19) InP EGA 21) 20) 176 Netsu Sokutei

3 TG (a) i (arbitrary unit) m / mg T (arbitrary unit) TG (b) Fig.2 EGA curves of thermal decomposition of two samples of poly(methyl methacrylate) under high vacuum. 26) The symbol, i, is the ion current. m / mg T (arbitrary unit) YBa 2Cu 3O 7 δ 22) DSC 23) 24,25) Fig.2 EGA 26) Fig.3 TG- curves of thermal decomposition of polyimide film in air flow. 27) The symbols, m and t, are the mass and the time, and the temperature difference T by is shown in an arbitrary unit. (a) Constant rate heating at 10 /min. (b) SCTG curve obtained at mass loss rate of 0.06 %/min H-TG Netsu Sokutei

4 (a) TG (a) ln [(dm /dt) / % min 1 ] ln [(dm /dt) / % min 1 ] T 1 / kk 1 (b) T 1 / kk 1 Fig.4 Friedman-Ozawa plot for thermal decomposition of polyimide film. 27) The symbols,, and, are respectively data by constant rate heating, SCTG and isothermal run. Mass loss conversion of 25 % (a) and 35 % (b). Fig.3(a)2 TGSCTG m / mg m / mg T (arbitrary unit) TG (b) T (arbitrary unit) Fig.5 Isothermal TG- curves of polyimide film in air flow obtained at 500 (a) and 550 (b). 27) Fig.3(b) SCTG 1 27) Friedman- Fig ) Friedman Fig.5 27) SCTG2 TG-EGA 28) 178 Netsu Sokutei

5 Rate jump Rate Constant Change Rate Constant Oscillation k t k t T T t Temperature jump t Temperature Oscillation Fig.6 Schematic explanation of jump methods. 1) The symbol, k, is the rate constant. Fig.7 Schematic explanation of temperature modulation method. 1) 8) SCTA SCTG TG TG 0.5 mg16 mg 10 mg SCTG0.5 mg TG 29,30) TG SCTG SCTG Fig.6 10) SCTA 11) 31,32) 33) EGA DSC 12,13) TG 14) EGA Netsu Sokutei

6 m / % Fig.8 (dm/dt) / % min 1 Temperature modulated TG curve of polytetrafluoroethylene. Fig.9 TG- curve of poly(methyl methacrylate) 14) by repeated temperature scanning. 34) (dm/dt) / % min 1 m / % TG T (arbitraty unit) DTG Fig.7 Fig.8 2 Fig.7 EGA TG Fig.8 TG 1 15) (dc /dt) / % min 1 C / % Fig.10 Equivalent isothermal curves of conversion (C ) versus conversion rate extracted from TG curve of poly(methyl methacrylate) in Fig.9. 34) 1,34) Fig.9 Fig ,34) Fig Netsu Sokutei

7 TG 35) 1 DSC 36) Isoconversion Methods -Flynn-Wall 19,37) Kissinger-- 38,39) Friedman- 40,41) 42) model free Friedman- TG Friedman- Friedman- -Flynn-Wall Kissinger-- TG Friedman- 3 Friedman- Elsevier Journal of Thermal Analysis and Calorimetry R. L. Blaine TA Netsu Sokutei

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