Hindered amines and their derived oxidation products, the hindered nitroxyls and hydroxylamines are processing stabilizers and photoantioxidants for poly(vinyl chloride). The evidence suggests that oxidation of the amines occurs very rapidly and completely during mechanooxidation and that the resulting redox couple operates by a catalytic mechanism as described previously for hydrocarbon polymers.
Adeniyi, J. B., Al-Malaika, S., & Scott, G. (1986). Mechanisms of antioxidant action: the role of nitroxyl radicals in the stabilization of PVC . Journal of Applied Polymer Science, 32(7), 6063-6071. https://doi.org/10.1002/app.1986.070320733