High-density polyethylene, molecular antioxidant

For high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), and PP combinations of phenolic antioxidants and phosphites lead to a synergistic protection of the polymer. For HDPE and LLDPE an increased amount of phosphite provided increased processing stability at constant phenol concentration. A 4 1 ratio of phosphite to phenol exhibited the best performance, while the most efficient ratio for protecting melt flow of the PP was found when a 2 1 ratio of phosphite to phenol was added [167], According to Parrondo molecular weight changes can best be reduced with phenolic antioxidants, while phosphites prevent discoloration [168]. 

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