Abstract: Useful stabilizer combinations and propylene polymer compositions stabilized therewith having improved resistance to discoloration upon processing are provided. The stabilizer combinations of the invention are comprised of a mixture of calcium salts of stearic acid and lactic acid and a tocopherol-containing mixture consisting essentially of .alpha.-tocopherol, glycerin, polyethylene glycol having an average molecular weight of about 300 and glycerol monocaprylate. Propylene homopolymers and random, block and impact copolymers of propylene are stabilized in accordance with the invention.

Abstract: Phillips' process high density polyethylene resin compositions having improved processing stability are obtained using a combination of stabilizers comprised of a hindered phenol and a phosphite compound having three cyclic phosphite moieties linked via a nitrogen atom. More specifically, the phosphite compound is 2, [[2,4,8,10-tetrakis(1,1-dimethylethyl)dibenzo[d,f][1,3,2]-dioxaphosphepin- 6-yl]oxy]-N,N-bis [2-[[2,4,8,10-tetrakis (1,1-dimethylethyl) dibenzo[d,f][1,3,2]dioxaphosphenpin-6-yl]oxy]-ethyl]ethanamine. With the HDPE compositions stabilized in accordance with the invention, it is possible to eliminate undesirable rapid changes in melt viscosity which can occur when Phillips' process HDPE resins are processed under conditions of high shear.