Limits on Convergence

Polymers are rendered more resistant to oxidation by the incorporation of a compound containing at least one phosphate grouping in which the phosphorus atom and at least two of the three oxygen atoms attached thereto by single covalent bonds form part of a cyclic structure, the remaining atoms in the ring being carbon atoms, such that when only two of the three said oxygen atoms form part of a cyclic structure the third said oxygen atom is attached to hydrogen, a metal, a metalloid group, an alkyl or substituted alkyl radical or a hindered aryl radical. The compound may be formed in situ in the polymer from a precursor in which one of the -C-O-P- links of the cyclic structure is replaced by -C-OH HO-P-, or from an organo-soluble metal salt and a hydroxyphosphate corresponding to the antioxidant.