TABLE OF CONTENTS Seven different techniques have been applied to the study of the oxidative stability of polymers:
Thermogravimetric analysis (TGA)
Differential scanning calorimetry (DSC)
Pressure differential scanning calorimetry (PDSC)
Evolved gas analysis (EGA)
Infrared spectroscopy
Electron spin resonance spectroscopy (ESR)
Matrix-assisted laser desorption/ionisation mass spectrometry (MALDI)
The theory and instrumentation of these techniques has been discussed in earlier chapters. See also Appendix 1.
Some examples of the applications of these techniques are discussed next.
In most cases thermal oxidation studies in polymers would be conducted under an inert gas such as nitrogen or helium in order to avoid the formation of secondary oxidation products that would complicate interpretation. In some cases, however, information is required on the stability to oxidation of polymeric materials and in these instances the thermal experiment would be carried out in an atmosphere of oxygen or air. Applications of the various techniques listed above to the determination of oxidative stability are discussed next.
In this technique the sample is heated in air or oxygen at a constant heating rate until complete oxidation or combustion occurs and weight changes are continuously recorded as a weight versus temperature plot. Often the shape of the derivative thermogram is typical for a certain polymer and can be used for characterisation.
Thizon and co-workers [1] have studied the effect of low concentrations of oxygen and water in nitrogen on the rate of thermal degradation of ethylene propylene copolymers. Using TGA they are able...
