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THERMAL ANALYSIS AND ANALYTICAL PYROLYSIS OF PHOSPHAZENE AND SILARYLENE-SILOXANE POLYMERS
Abstract
Thermal analysis and analytical pyrolysis have been performed on selected phosphazene and silarylene-siloxane polymers for the following purposes: first, to investigate their low and high temperature behavior, secondly, to evaluate gas chromatography-element selective detection as a tool for analytical pyrolysis and lastly, to identify the pyrolysis products and to propose degradation mechanisms for these polymers. Thermal analytical techniques employed were differential scanning calorimetric (DSC) and thermal gravimetric analyses (TGA) as well as elemental analyses. For the phosphazenes, elemental analyses gave results consistent with those predicted from the repeating structures of the polymers. DSC and TGA data were also consistent with that reported for phosphazenes of similar structure in the literature. For the silarylene-siloxanes elemental analyses, DSC and TGA data were all inconsistent with data reported in the literature. Attempts to elucidate the reason(s) for these discrepancies using infrared, ('1)H NMR, and ('13)C NMR spectroscopies and gel permeation chromatography were inconclusive. Two methods of element selective detection were evaluated in the analytical pyrolysis studies. First, pyrolysis-gas chromatography-microwave induced atmospheric pressure helium emission spectroscopic detection (Py-GC-MED) was applied to the phosphazenes for element selective detection of carbon, phosphorus and halogens at three pyrolysis temperatures. Secondly, pyrolysis-gas chromatography-direct current argon plasma emission spectroscopic detection (Py-GC-DCP) was applied to the silarylene-siloxanes for element selection detection of silicon. Simultaneous carbon detection was accomplished by flame ionization detection (FID). The utility of both these plasma emission spectroscopic detectors for element selective fingerprint analysis of heteroatom containing polymers was demonstrated. Pyrolysis-gas chromatography-electron impact (EI) and chemical ionization (CI) mass spectrometry was used for the identification of pyrolysis products from both phosphazene and silarylene-siloxane polymers. A detailed degradation mechanism for poly{bis(2,2,2-trifluoroethoxy) phosphazene} was proposed based on the products observed. The presence of the D(,3), D(,4) and D(,5) dimethylcyclosiloxanes in the pyrolysis products of the silarylene-siloxane polymers indicated that intermolecular rearrangment of siloxane portions of the polymers most likely occurred. The results of this work illustrate the broad range of useful data obtainable using thermal analysis, element selective detection and mass spectrometry together in polymer pyrolysis studies.
Subject Area
Analytical chemistry
Recommended Citation
RISKA, GREGORY DONALD, "THERMAL ANALYSIS AND ANALYTICAL PYROLYSIS OF PHOSPHAZENE AND SILARYLENE-SILOXANE POLYMERS" (1983). Doctoral Dissertations Available from Proquest. AAI8310326.
https://scholarworks.umass.edu/dissertations/AAI8310326