Application of New Kinetic Techniques to the Lifetime Prediction of Polymers from Weight-Loss Data.
Abstract
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 K/min. to 9 K/day; 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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1978
- Accession Number
- ADA063060
Entities
People
- Brian Dickens
- Joseph H. Flynn
Organizations
- National Institute of Standards and Technology