ABSTRACT
Polymer materials are used in a wide range of working conditions. Low temperatures for a long time and high temperatures for a short time represent typical extremes. Changes are induced by both chemical and physical processes. Thin films of thermoplastic polymer melt were applied to a metal plate preheated to a given temperature. A film of 7 µm thick was formed on the plate surface. A white spot trace is observed which disappears like a comet tail. The length of the tail divided by the rate of movement determines the lifetime with high accuracy. At relatively low temperatures visual and thermocouple measurements were used. At relatively high temperatures during short time periods when destruction does not occur there exist both long blocks from non-associated monomer links and short blocks from associated ones. Evidently, the reactions at the chain ends can be neglected. In large blocks simultaneous breaks of several chain parts are thermodynamically possible.
