TABLE OF CONTENTS These procedures are used extensively for the direct isolation or release of volatile components from a polymeric matrix and may involve the combined use of vacuum and heat, as for example in the MS direct insertion probe or during dry vacuum distillation. Alternatively, the volatiles may be swept from the heated sample by a flow of inert gas for concentration by freeze trapping and/or collection on to a solid adsorbent prior to thermal or solvent desorption for GC or MS examination.
Schr der [38] warns that during solvent extraction techniques there may be complications, which can result in faulty interpretation of results due to stabiliser rearrangements or decompositions. However, although oxidation of the polymer additives during extraction may be avoidable, there exists the danger that crushing the polymer prior to extraction may lead to a sequence of reactions, which affect the chemical structure of the inhibitor. All polymers of longer chain length suffer from degradation when under mechanical stress which usually starts by a chain rupture in the centre of the macromolecule and results in the formation of macro radicals. This degradation is accelerated at low temperatures and even occurs when cutting with a knife. Pazonyi and co-workers [39] found a linear relationship between the radical concentration (determined by the consumption of diphenyl-picrylhydrazyl) and the surface (Figure 2.5) when cutting PE and plasticised PVC. They could prove that this could occur when the chemical bonds with polymers, which...
