Thermally stable cellulose ester compositions and articles made using these compositions

A composition comprising a cellulose ester;

• a secondary antioxidant in the range of from 0.1 to 0.8 wt %;
• an acid scavenger in the range of from 0.2 to 1.0 wt %;
• and a salt stabilizer in the range of from 0.01 to 0.1 wt %;
• wherein the cellulose ester is a cellulose acetate propionate,
• wherein the composition is plasticizer free,
• wherein the secondary antioxidant is an orpanophosphorous or orpanosulfur compound,
• wherein the acid scavenger is an epoxidized fatty acid ester,
• wherein the salt stabilizer is a compound wherein the cation component is aluminum, calcium, magnesium, copper, cerium, antimony, nickel, cobalt, manganese, barium, strontium, zinc, zirconium, tin, cadmium, chromium or iron, and the anion component is a (C6-20)alicyclic carboxylic acid, a (C2-20)alkyl carboxylic acid, or a (C6-20)alkenyl carboxylic acid, wherein the (C6-20)alicyclic carboxylic acid, the (C2-20)alkyl carboxylic acid, or the (C6-20)alkenyl carboxylic acid is naphthenic acid, abietic acid, cyclohexane carboxylic acid, cyclohexane propionic acid, 3-methyl-cyclopentyl acetic acid, 4-methylcyclohexane carboxylic acid, 2,2,6-trimethylcyclohexane carboxylic acid, 2,3-dimethylcyclopentyl acetic acid, 2-methylcyclopentyl propionic acid, palmitic acid, stearic acid, oleic acid, or lauric acid,
• wherein the weight percentages of the cellulose ester, the secondary antioxidant, the acid scavenger, and the salt stabilizer are based on the total weight of the composition,
• wherein the composition has a heat distortion temperature (“HDT”) that is in the range of from 95° C. to 140° C. according to ASTM D648 as measured at 1.82 MPa using a 3.2 mm thick bar subjected to 70° C. for 4 hours,
• wherein the change in the absolute weight average molecular weight (“Mw”) of the cellulose ester due to injection molding is less than 30% when the composition is injection molded with a barrel temperature of 260° C. with a residence time of 5 min,
• wherein the b* value is less than 15 as measured according to ASTM E1348 using a 3.2 mm plaque made from the composition which has been injection molded with a barrel temperature of 249° C. with a residence time of 5 min.