Retarding depolymerization of poly(methyl methacrylate) grafted onto a propylene polymer

A process for retarding the depolymerization of poly(methyl methacylate) that has been graft polymerized onto a backbone of propylene polymer material, the process comprising mixing about 0.025 parts to about 5.0 parts of a hydroxylamine compound having the formula T.sub.1 T.sub.2 NOH, where T.sub.1 is a 1 to 36 carbon alkyl group, a 5 to 12 carbon cycloalkyl group, a 7 to 9 carbon aralkyl group, or the aralkyl group substituted by a 1 to 4 carbon alkyl group or by one or two halogen atoms and T.sub.2 is hydrogen or has the same meaning as T.sub.1, per hundred parts of a polymer material comprising a graft copolymer comprising a backbone of a propylene polymer material having graft polymerized thereto poly(methyl methacrylate) or a copolymer of methyl methacrylate and at least one other monomer, wherein the total amount of polymerized monomer is about 10 parts to about 120 parts per hundred parts of the propylene polymer material and the comonomer, when present, is present in an amount up to 20 mol % of the total polymerized monomers.