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Analysis of the coupling between the apparent time scale of thermal degradation and sample size
Author(s) -
Cohen Arie,
Carriere Craig J.,
Pasztor Andrew J.
Publication year - 1993
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760330602
Subject(s) - materials science , degradation (telecommunications) , isothermal process , thermogravimetric analysis , thermal diffusivity , gravimetric analysis , thermal stability , thermal , thermal analysis , coupling (piping) , composite material , volatilisation , thermodynamics , chemical engineering , chemistry , computer science , organic chemistry , telecommunications , physics , engineering
Sample size sensitivity of thermal gravimetric analysis (TGA) presents a serious handicap in the obtaining of reliable thermal stability data for high‐temperature applications. For example, predictions of the apparent time for degradation during an isothermal experiment based on the results obtained using a 10 μm thick specimen can be off by an order of magnitude when applied to a product with a thickness of 10 cm. To address this effect, TGA experiments studying the thermal degradation of poly(methyl methacrylate) were conducted. Analysis of the experimental data resulted in the development of a relationship between the apparent time scale of the thermal degradation and the specimen thickness. Origins of the new dependence were traced to the change of the diffusivity resulting from material volatilization. Implications of the coupling between these two events for the analysis of thermal stability for new polymeric materials are discussed, and required changes in the current methodology are outlined.