The chemistry of poly(vinyl chloride) stabilization. V. Organotin stabilizers having radioactively tagged Y groups

Experiments with a select group of radioactively tagged organotin stabilizers of the general formula Bu2Sn Y2, in which the radioactive atoms (14C) are located in the Y groups, have shown, that, under the conditions normally employed to evaluate and screen poly(vinyl chloride) heat stabilizers, a portion of that radioactivity becomes firmly associated with the resin. Under standard conditions, the extent of this association has been found to be dependent upon the nature of the Y group and the duration of the heat treatment. It is suggested that the stabilizing action of these organotin compounds arises in part from reactions between the polymer and the stabilizer wherein certain of the polymer's chlorine atoms are exchanged for the stabilizer's Y groups (or a portion thereof), the resulting structure being more stable toward degradative elimination. Other possibilities for reaction between the polymer and the stabilizer are also considered and it is shown how these can further supplement the organotin compound's stabilizing action and yet be rationalized within the experimental evidence.