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

Li Zhang; Yongqiang Dai; Yi Kai; Ri-guang Jin

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

Carbon Letters
Abbr : Carbon Lett.
2011, 12(4), pp.229-235
Publisher : Korean Carbon Society
Research Area : Natural Science > Natural Science General > Other Natural Sciences General

Li Zhang ¹, Yongqiang Dai ¹, Yi Kai ¹, Ri-guang Jin ¹

¹Beijing University of Chemical Technology

Candidate

ABSTRACT

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.

KEYWORDS

high isotacticity, polyacrylonitrile, stabilization, kinetics, iso-conversional

Citation status

* References for papers published after 2023 are currently being built.

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