Structural evolution and kinetic study of high isotacticity poly(acrylonitrile) during isothermal pre-oxidation

서지정보

· 발행기관 : 한국탄소학회
· 수록지 정보 : Carbon Letters / 12권 / 4호
· 저자명 : LiZhang, YongqiangDai, YiKaiandRi-guangJin

목차

1. Introduction
2. Experiment
3. Characterization
4. Results and Discussion
5. Conclusions
References

초록

Isotactic polyacrylonitrile (PAN) with triad isotacticity of 0.53, which was determined by
13C nuclear magnetic resonance, using dialkylmagnesium as an initiator, was successfully
synthesized. Isothermal treatment of iso-PAN was conducted in air at 200, 220, 250 and
280oC. Structural evolutions and chemical changes were studied with Fourier transformation
infrared and wide-angle X-ray diffraction during stabilization. A new parameter carbon
nanofiber = I2240cm
-1/ (I1595cm
-1+f*I1595cm
-1) was defined to evaluate residual nitrile groups.
Crystallinity and crystal size were calculated with X-ray diffraction dates. The results
indicated that the nitrile groups had partly converted into a ladder structure as stabilization
proceeded. The rate of reaction increased with treatment temperature; crystallinity and
crystal size decreased proportionally to pyrolysis temperature. The iso-conversional method
coupled with the Kissinger and Flynn-Wall-Ozawa methods were used to determine kinetic
parameters via differential scanning calorimetry analysis with different heating rates. The
active energy of the reaction was 171.1 and 169.1 kJ/mol, calculated with the two methods
respectively and implied the sensitivity of the reaction with temperature.

영어초록

Isotactic polyacrylonitrile (PAN) with triad isotacticity of 0.53, which was determined by13C nuclear magnetic resonance, using dialkylmagnesium as an initiator, was successfullysynthesized. Isothermal treatment of iso-PAN was conducted in air at 200, 220, 250 and280oC. Structural evolutions and chemical changes were studied with Fourier transformationinfrared and wide-angle X-ray diffraction during stabilization. A new parameter carbonnanofiber = I2240cm-1/ (I1595cm-1+f*I1595cm-1) was defined to evaluate residual nitrile groups.Crystallinity and crystal size were calculated with X-ray diffraction dates. The resultsindicated that the nitrile groups had partly converted into a ladder structure as stabilizationproceeded. The rate of reaction increased with treatment temperature; crystallinity andcrystal size decreased proportionally to pyrolysis temperature. The iso-conversional methodcoupled with the Kissinger and Flynn-Wall-Ozawa methods were used to determine kineticparameters via differential scanning calorimetry analysis with different heating rates. Theactive energy of the reaction was 171.1 and 169.1 kJ/mol, calculated with the two methodsrespectively and implied the sensitivity of the reaction with temperature.

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