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The pyrolysis behaviors of ternary copolyimide derived from aromatic dianhydride and aromatic diisocyanates
Author(s) -
Guo Binghua,
Chen Lei,
Yu Junrong,
Zhu Jing,
Wang Guizhen,
Hu Zuming
Publication year - 2014
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.40165
Subject(s) - thermogravimetric analysis , thermal decomposition , thermal stability , polymer chemistry , isocyanate , condensation polymer , activation energy , materials science , polyimide , fourier transform infrared spectroscopy , glass transition , chemistry , organic chemistry , polyurethane , polymer , chemical engineering , engineering , layer (electronics)
A polyimide (PI) based on benzophenone‐3,3′,4,4′‐tetracarboxylic acid dianhydride, toluene diisocyanate (TDI), and 4,4′‐methylenebis (phenyl isocyanate) (MDI) has been synthesized via a one‐step polycondensation procedure. The resulting PI possessed excellent thermal stability with the glass transition temperature ( T g ) 316°C, the 5% weight loss temperature ( T 5% ) in air and nitrogen 440.4°C and 448.0°C, respectively. The pyrolysis behaviors were investigated with dynamic thermogravimetric analysis (TGA), TGA coupled with Fourier transform infrared spectrometry (TGA–FTIR) and TGA coupled with mass spectrometry (TGA–MS) under air atmosphere. The results of TGA–FTIR and TGA–MS indicated that the main decomposition products were carbon dioxide (CO 2 ), carbonic oxide (CO), water (H 2 O), ammonia (NH 3 ), nitric oxide (NO), hydrogen cyanide (HCN), benzene (C 6 H 6 ), and compounds containing NH 2 , CN, NCO or phenyl groups. The activation energy ( E a ) of the solid‐state process was estimated using Ozawa–Flynn–Wall (OFW) method which resulted to be 143.8 and 87.8 kJ/mol for the first and second stage. The pre‐exponential factor ( A ) and empirical order of decomposition ( n ) were determined by Friedman method. The activation energies of different mechanism models were calculated from Coats–Redfern method. Compared with the activation energy values obtained from the OFW method, the actual reaction followed a random nucleation mechanism with the integral form g (α) = −ln(1 − α). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131 , 40163.