DEGRADATION BEHAVIOR OF NATURAL-RUBBER DURING THE MASTICATION WITH MASTICATION AGENTS

To accelerate the molecular degradation during the mastication process of NR mastication agents are used. The authors describe how to compar e the mechanisms of degradation caused by oxygen and by pentachlorthio phenol derivates. Molar mass averages were determined by solution visc osity measurements. Molar mass distributions and averages were determi ned by gel permeation chromatography. Samples of the same bale were ma sticated in a laboratory internal mixer and on laboratory mills by a r eproducible process. Experiments were repeated in an nitrogen atmosphe re. Oxygen and pentachlorthiophenol are active as radical scavenger an d radical carrier, but there are no synergistic effects of any importa nce under technical interesting conditions. At high molecular masses a nd high bulk viscosities mixing aggregates force mechanical ruptures o f molecules. This generates radicals and activates the mastication age nts. An improvement of the technical mastication process on the basis of the shown results is possible.