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Thermal degradation of segmented polyurethanes
Author(s) -
Petrović Zoran S.,
Zavargo Zoltan,
Flyn Joseph H.,
Macknight William J.
Publication year - 1994
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.1994.070510615
Subject(s) - activation energy , degradation (telecommunications) , polyurethane , thermogravimetric analysis , polymer , kinetic energy , materials science , thermal stability , thermal , process (computing) , polymer chemistry , chemical engineering , composite material , thermodynamics , chemistry , organic chemistry , computer science , physics , telecommunications , engineering , quantum mechanics , operating system
Thermal degradation of polyurethane samples was studied by a thermogravimetric method. The effect of soft‐segment length and soft‐segment concentration on activation energy of the degradation process was measured. Three methods of calculation gave activation energies at different stages of the very complex weight loss process. It was shown that at initial stages of the weight loss the process was dominated by hard‐segment degradation. Activation energy of the whole process calculated by the Ozawa–Flynn method did not offer clear insight into the structure–stability relationship of polyurethanes. The second method showed that activation energy of the initial stage of degradation increased with decrease in hard‐segment length. The Flynn method of calculating activation energy produced fairly constant activation energy of the first 40% degradation, at around 150 kJ/mol, for polymers in the C series. Generally, calculation of kinetic parameters of a complex degradation process as in polyurethanes gives results that are not easy to interpret. It has been shown qualitatively that polymers with higher soft‐segment concentration display lower initial weight loss and higher onset temperatures of degradation. © 1994 John Wiley & Sons, Inc.