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Thermal Degradation of Fractionated High and Low Molecular Weight Polystyrenes

In previous work on the thermal degradation of polystyrene of average molecular weight of 230,000, carried out in a vacuum in the temperature range 318 to 348 °C, the rate curves exhibited distinct maximums when percentage loss of sample per minute was plotted as a function of percentage volatilizat...

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Detalles Bibliográficos
Autores principales: Madorsky, S. L., Mclntyre, D., O’Mara, J. H., Straus, S.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: [Gaithersburg, MD] : U.S. Dept. of Commerce, National Institute of Standards and Technology 1962
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5312812/
http://dx.doi.org/10.6028/jres.066A.029
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author Madorsky, S. L.
Mclntyre, D.
O’Mara, J. H.
Straus, S.
author_facet Madorsky, S. L.
Mclntyre, D.
O’Mara, J. H.
Straus, S.
author_sort Madorsky, S. L.
collection PubMed
description In previous work on the thermal degradation of polystyrene of average molecular weight of 230,000, carried out in a vacuum in the temperature range 318 to 348 °C, the rate curves exhibited distinct maximums when percentage loss of sample per minute was plotted as a function of percentage volatilization. These maximums correspond to a volatilization of about 35 to 45 percent and tend to flatten with decreased temperature of pyrolysis. A similar study of rates of thermal degradation at 307.5 °C has now been made on two groups of polymers: (1) low molecular weight, 24,000; 51,000; and 66,000; and (2) high molecular weight, 2,000,000; 2,250,000; and 5,000,000. Whole polymers and also fractions of narrow-range molecular weight were used. The rate curves for the 24,000 and 51,000 molecular-weight samples exhibit very high initial rates, but no maximums; the 66,000 sample showed a maximum at 45 percent volatilization. The rate curves for the 2,000,000, 2,250,000, and 5,000,000 molecular-weight samples exhibit a gradual rise up to about 25 percent volatilization; then, instead of forming maximums, they follow plateaus to about 50 percent volatilization. These plateaus are indicative of a zero-order reaction in the range that they cover, and the rates corresponding to them fit well on the Arrhenius activation-energy curve obtained previously for polystyrene samples at higher temperatures.
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spelling pubmed-53128122023-06-15 Thermal Degradation of Fractionated High and Low Molecular Weight Polystyrenes Madorsky, S. L. Mclntyre, D. O’Mara, J. H. Straus, S. J Res Natl Bur Stand A Phys Chem Article In previous work on the thermal degradation of polystyrene of average molecular weight of 230,000, carried out in a vacuum in the temperature range 318 to 348 °C, the rate curves exhibited distinct maximums when percentage loss of sample per minute was plotted as a function of percentage volatilization. These maximums correspond to a volatilization of about 35 to 45 percent and tend to flatten with decreased temperature of pyrolysis. A similar study of rates of thermal degradation at 307.5 °C has now been made on two groups of polymers: (1) low molecular weight, 24,000; 51,000; and 66,000; and (2) high molecular weight, 2,000,000; 2,250,000; and 5,000,000. Whole polymers and also fractions of narrow-range molecular weight were used. The rate curves for the 24,000 and 51,000 molecular-weight samples exhibit very high initial rates, but no maximums; the 66,000 sample showed a maximum at 45 percent volatilization. The rate curves for the 2,000,000, 2,250,000, and 5,000,000 molecular-weight samples exhibit a gradual rise up to about 25 percent volatilization; then, instead of forming maximums, they follow plateaus to about 50 percent volatilization. These plateaus are indicative of a zero-order reaction in the range that they cover, and the rates corresponding to them fit well on the Arrhenius activation-energy curve obtained previously for polystyrene samples at higher temperatures. [Gaithersburg, MD] : U.S. Dept. of Commerce, National Institute of Standards and Technology 1962 1962-08-01 /pmc/articles/PMC5312812/ http://dx.doi.org/10.6028/jres.066A.029 Text en https://creativecommons.org/publicdomain/zero/1.0/ The Journal of Research of the National Bureau of Standards Section A is a publication of the U.S. Government. The papers are in the public domain and are not subject to copyright in the United States. Articles from J Res may contain photographs or illustrations copyrighted by other commercial organizations or individuals that may not be used without obtaining prior approval from the holder of the copyright.
spellingShingle Article
Madorsky, S. L.
Mclntyre, D.
O’Mara, J. H.
Straus, S.
Thermal Degradation of Fractionated High and Low Molecular Weight Polystyrenes
title Thermal Degradation of Fractionated High and Low Molecular Weight Polystyrenes
title_full Thermal Degradation of Fractionated High and Low Molecular Weight Polystyrenes
title_fullStr Thermal Degradation of Fractionated High and Low Molecular Weight Polystyrenes
title_full_unstemmed Thermal Degradation of Fractionated High and Low Molecular Weight Polystyrenes
title_short Thermal Degradation of Fractionated High and Low Molecular Weight Polystyrenes
title_sort thermal degradation of fractionated high and low molecular weight polystyrenes
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5312812/
http://dx.doi.org/10.6028/jres.066A.029
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