Application of New Kinetic Techniques to the Lifetime Prediction of Polymers from Weight-Loss Data.
NATIONAL BUREAU OF STANDARDS WASHINGTON DC POLYMER SCIENCE AND STANDARDS DIV
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Prediction of the lifetime of a polymer by extrapolation of weight-loss data is a tenuous procedure and a thorough analysis of the kinetics over a wide temperature range is a requisite. Several experimental methods and kinetic analytical techniques have been developed which are designed to overcome the problems of conventional methods. These include 1 a factor-jump method in which a fully automated and minicomputer directed system calculates activation energies using one sample and a series of short, isothermal plateaus, this avoids complications from the comparison of samples with diverse properties and thermal histories. 2 a diagnostic test for the consistency of kinetic parameters over a broad region of temperature and conversion. 3 a comparison of experiments performed at constant heating rates from 6 Kmin. to 9 Kday this allows an insight into the mode of kinetic coupling of competing processes and better prediction of the dominant low-temperature process. 4 a detailed analysis of the kinetics of the first several percentages weight-loss at slow heating rates and low temperatures many polymers lose their useful properties in this region. These methods are being applied to polystyrene and polyurethanes in vacuum, nitrogen, and nitrogen-oxygen mixtures. Author
- Polymer Chemistry
- Numerical Mathematics