The thermal degradation kinetics of polypropylene : Part III. Thermogravimetric analyses

Abstract Thermogravimetric data were obtained for the pyrolysis of polypropylene, and several previously published interpretation methods were applied to the data. However, the wide temperature range used in this work (45–580 °C) encompassed a change in the decomposition mechanism and this greatly limited the utility of the methods. To accommodate this mechanism change, the data were treated as a pseudo first-order reaction. It was observed that the data conformed to a first-order fit at temperatures of less than 404 to 421 °C (depending upon heating rate) with an activation energy of 98.3 ± 3.1 kJ/mol. At higher temperatures the data could again be fit as a pseudo first-order reaction, but with an activation energy of 327.9 ± 8.6 kJ/mol. The two regions were separated by a relatively narrow transition region. The lower activation energy occurring at lower degradation temperatures is attributed to scission of ‘weak links’ in the polymer. The higher activation energy was similar to the carbon-carbon bond dissociation energy and is associated with random scission throughout the polymer.

[1]  Joseph H. Flynn,et al.  General Treatment of the Thermogravimetry of Polymers. , 1966, Journal of research of the National Bureau of Standards. Section A, Physics and chemistry.

[2]  J. Flynn.  The isoconversional method for determination of energy of activation at constant heating rates , 1983 .

[3]  T. Ozawa.  Applicability of Friedman plot , 1986 .

[4]  C. D. Doyle.  Estimating isothermal life from thermogravimetric data , 1962 .

[5]  David A. Anderson,et al.  The kinetics of the thermal degradation of polystyrene and polyethylene , 1961 .

[6]  H. E. Kissinger.  Reaction Kinetics in Differential Thermal Analysis , 1957 .

[7]  J. Graydon,et al.  Interpretation of activation energies calculated from non-isothermal transformations of amorphous metals , 1994 .

[8]  T. Ozawa.  Non-isothermal kinetics and generalized time , 1986 .

[9]  N. Grassie,et al.  Some aspects of the photo, photothermal and thermal decomposition of polypropylene under vacuum , 1975 .

[10]  T. Ozawa.  A New Method of Analyzing Thermogravimetric Data , 1965 .

[11]  James C. W. Chien,et al.  Polymer reactions. V. Kinetics of autoxidation of polypropylene , 1967 .

[12]  H. Jellinek.  Thermal degradation of polystyrene. Part II , 1948 .

[13]  J. Chien,et al.  Polymer reactions, 8. Oxidative pyrolysis of poly(propylene)†‡ , 1980 .

[14]  Masayoshi Okubo,et al.  Makromol Chem-Macromol Symp , 1990 .

[15]  J. Chien,et al.  Oxygen diffusion limitation in autoxidation of polypropylene , 1966 .

[16]  A. Broido.  A simple, sensitive graphical method of treating thermogravimetric analysis data , 1969 .

[17]  M. White,et al.  The structure and properties of evaporated polyethylene thin films , 1970 .

[18]  A. Simonelli,et al.  Thermal analysis of dielectric insulation, ethylene/propylene rubbers, and cross-linked polyethylenes decomposed in a nitrogen atmosphere† , 1976 .

[19]  J. Flynn.  Thermal analysis kinetics-problems, pitfalls and how to deal with them , 1988 .

[20]  B. Dickens.  Thermal degradation study of isotactic polypropylene using factor‐jump thermogravimetry , 1982 .

[21]  P. C. Uden,et al.  Polymer reactions—Part VII: Thermal pyrolysis of polypropylene , 1980 .

[22]  H. Horowitz,et al.  A New Analysis of Thermogravimetric Traces. , 1963 .

[23]  Eli S. Freeman,et al.  The Application of Thermoanalytical Techniques to Reaction Kinetics: The Thermogravimetric Evaluation of the Kinetics of the Decomposition of Calcium Oxalate Monohydrate , 1958 .

[24]  A. W. Coats,et al.  Kinetic parameters from thermogravimetric data. II. , 1965 .

[25]  S. L. Madorsky.  Thermal Degradation of Organic Polymers , 1964 .

[26]  Leo Reich,et al.  Elements of polymer degradation , 1971 .

[27]  R. Conley.  Thermal stability of polymers , 1970 .

[28]  T. Ozawa,et al.  Kinetic analysis of derivative curves in thermal analysis , 1970 .