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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...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
[Gaithersburg, MD] : U.S. Dept. of Commerce, National Institute of Standards and Technology
1962
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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. |
format | Online Article Text |
id | pubmed-5312812 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 1962 |
publisher | [Gaithersburg, MD] : U.S. Dept. of Commerce, National Institute of Standards and Technology |
record_format | MEDLINE/PubMed |
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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