Mastication. Part III. Chemical verification of the mechanical degradation mechanism of cold mastication

The mechanism of cold mastication of natural and synthetic rubbers, as proposed by Kauzmann and Eyring, and by Pike and Watson, in volves the mechanical rupture of the polymer chain yielding polymer radicals which are stabilized by interaction with radical‐acceptor molecules to give the degraded polymer. This mechanism has been verified by a spectroscopic study of the cold mastication of natural rubber with 1,1‐diphenyl1‐2‐picryl hydrazyl and a radioisotopic tracer study of the cold mastication of GR‐S using [S 35 ]‐labeled 1,1′‐dinaphthyl disulfide as the radical‐acceptor molecule. Correlation of the decrease in molecular weight of the polymer and the amount of radical acceptor in corporated during the cold mastication process agrees with prediction according to the mechanical degradation mechanism.