A composition comprising: (A) an ethylene/alpha-olefin/diene interpolymer; (B) a peroxide comprising at least one -O-O- peroxide bond; (C) a bis-TEMPO compound having the Structure I wherein R 1 , R 2 , R 3 and R 4 are each independently selected from the group consisting of H and C 1 -C 6 alkyl groups; X is selected from the group consisting of S, O, N, P, Se, a carbonyl group (C=O), a carboxyl group (O-C=O), an amide group (N-C=O), an azo group (N=N), an imino group (C=N), a carbamate group (N-C=O), a peroxy group (O-O), a phosphono group (-(O) 2 P=O), a phosphate group (O=P-(O) 3 ), a sulfonyl group ((O=) 2 S), a sulfinyl group (O=S), a sulfonate ester group ((O=) 2 S-O), a sulfonate ester group (O=S-O), and combinations thereof; Y is selected from the group consisting of a substituted or unsubstituted aliphatic alkyl group, a substituted or unsubstituted aromatic alkyl group, a heterocyclic group, a siloxane group, an ethylene glycol group, an imide group, and combinations thereof; and n is greater than 1, and wherein the ratio of the molar amount of nitroxide (NO') groups of component (C) to the molar amount of the peroxide bonds of component (B) is from 0.100:1.000 to 1.000:1.000. (A) an ethylene/alpha-olefin/diene interpolymer; (B) a peroxide comprising at least one -O-O- peroxide bond; (C) a bis-TEMPO compound having the Structure I wherein R 1 , R 2 , R 3 and R 4 are each independently selected from the group consisting of H and C 1 -C 6 alkyl groups; X is selected from the group consisting of S, O, N, P, Se, a carbonyl group (C=O), a carboxyl group (O-C=O), an amide group (N-C=O), an azo group (N=N), an imino group (C=N), a carbamate group (N-C=O), a peroxy group (O-O), a phosphono group (-(O) 2 P=O), a phosphate group (O=P-(O) 3 ), a sulfonyl group ((O=) 2 S), a sulfinyl group (O=S), a sulfonate ester group ((O=) 2 S-O), a sulfonate ester group (O=S-O), and combinations thereof; Y is selected from the group consisting of a substituted or unsubstituted aliphatic alkyl group, a substituted or unsubstituted aromatic alkyl group, a heterocyclic group, a siloxane group, an ethylene glycol group, an imide group, and combinations thereof; and n is greater than 1, and wherein the ratio of the molar amount of nitroxide (NO') groups of component (C) to the molar amount of the peroxide bonds of component (B) is from 0.100:1.000 to 1.000:1.000. wherein R 1 , R 2 , R 3 and R 4 are each independently selected from the group consisting of H and C 1 -C 6 alkyl groups; X is selected from the group consisting of S, O, N, P, Se, a carbonyl group (C=O), a carboxyl group (O-C=O), an amide group (N-C=O), an azo group (N=N), an imino group (C=N), a carbamate group (N-C=O), a peroxy group (O-O), a phosphono group (-(O) 2 P=O), a phosphate group (O=P-(O) 3 ), a sulfonyl group ((O=) 2 S), a sulfinyl group (O=S), a sulfonate ester group ((O=) 2 S-O), a sulfonate ester group (O=S-O), and combinations thereof; Y is selected from the group consisting of a substituted or unsubstituted aliphatic alkyl group, a substituted or unsubstituted aromatic alkyl group, a heterocyclic group, a siloxane group, an ethylene glycol group, an imide group, and combinations thereof; and n is greater than 1, and wherein the ratio of the molar amount of nitroxide (NO') groups of component (C) to the molar amount of the peroxide bonds of component (B) is from 0.100:1.000 to 1.000:1.000. <EOS>