Effect of bromination on the thermal properties of poly(2,6-dimethyl-1,4-phenylene oxide) |
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Authors: | R C Bopp U Gaur R P Kambour B Wunderlich |
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Institution: | (1) Department of Chemistry, Rensselaer Polytechnic Institute Troy, 12181 NY;(2) Polymer Physics and Engineering Branch, Corporate Research and Development General Electric Company Schenectady, 12301 NY, USA;(3) Present address: Personal Products Company, Division of Johnson and Johnson, Inc., 08850 Milltown, NJ, USA |
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Abstract: | The thermal behavior of poly(2,6-dimethyl-1,4-phenyiene oxide) (PPO R resin), poly(3-bromo-2,6-dimethyl-1,4-phenylene oxide), and a series of their statistical copolymers with identical average molecular lengths has been characterized by thermogravimetry and computer-interfaced differential scanning calorimetry. The heat capacities are found to be additive with respect to the concentrations of the two components. The change in heat capacity at the glass transition ( C
p) is independent of composition for bromination of up to 75% of the repeat units. At higher bromine levels C
p decreases abruptly. This behavior is attributed to the temperature dependence of C
p for the two components. The glass transition temperature (T
g) of the copolymers varies nearly linearly with composition. A comparison of the experimental values ofT
g is made with various equations derived for statistical copolymers and homogeneous polymer blends. A modification of the Couchman equation is presented taking into account the temperature dependence ofC
p.
Zusammenfassung Das thermische Verhalten von Poly(2.6-dimethyl-1.4-phenylenoxyd) (PPO R-Harz), Poly(3-brom-2.6-dimethyl-1.4-phenylenoxyd) und einer Reihe von statistischen Copolymeren dieser Verbindungen mit gleicher durchschnittlicher Moleküllänge wurde durch Thermogravimetrie und Differential-Scanning-Kalorimetrie mit Computerinterface charakterisiert. Die Wärmekapazitäten sind hinsichtlich der Konzentrationen der beiden Komponenten additiv. Die Veränderung in der Wärmekapazität beim Übergang zum Glas (Cp) ist unabhängig von der Zusammensetzung bei Bromierung bis zu 75% der wiederho-lungseinheiten. Bei höheren Bromierungsgraden nimmtC
p abrupt ab. Dieses Verhalten wird der Temperaturabhängigkeit vonC
p der beiden Komponenten zugeschrieben. Die Glasübergangstemperatur (Tg) der Copolymeren verändert sich nahezu linear mit der Zusammensetzung. Ein Vergleich der experimentellen Werte von Tg wird mit verschiedenen für statistische Copolymere und Mischungen homogener Polymere abgeleiteten Gleichungen ausgeführt. Eine die Temperaturabhängigkeit vonC
p berücksichtigende Modifikation der Gleichung von Couchman wird angegeben.
, , (2,6- -1,4), (3--2,6--1,4- ) . , ë . ë (C
) 75%. C
. C
. T
. . T
. , . , C
.
This work was supported by the National Science Foundation, Polymers Program (DMR 78-15279) and the General Electric Corporate Research and Development Center. The authors are indebted to the following individuals at General Electric CRD for their experimental assistance: S. R. Weissman and P. E. Gundlach (molecular weight characterizations); D. W. Marsh (X-ray analysis); V. H. Watkins and E. L. Hall (electron microscopy); and N. A. Marotta (thermogravimetry). P. E. Donahue and E. A. Williams are gratefully acknowledged for carrying out and interpreting the NMR experiments. One of the authors (R. C. Bopp) would like to thank A. R. Shultz, J. T. Bendler, and D. M. White at General Electric CRD for their helpful discussions of this work and express his sincere appreciation to Professor P. R. Couchman (Rutgers University) for his illuminating discussions of the thermodynamic basis of his equation. |
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