Polymer substrates, for example ABS, PBT, PVC, PET, nylon 6, nylon 6′6, ABS/PBT, PC/ABS or ionomers, are made scratch resistant by the incorporation therein of an additive combination of b) a carboxylic acid reagent functionalized olefin polymer or copolymer and c) a primary or secondary fatty acid amide. The present polymers exhibit good weatherability, scratch resistance, good processability, good mechanical strength, good gloss retention and are non-sticky. The carboxylic acid reagent functionalized olefin polymer is for example maleic anhydride grafted polypropylene or polyethylene, or is a reaction product of maleic anhydride and an alpha-olefin, or is a tallow alcohol ester of said maleic anhydride products. The fatty acid amide is for example oleyl palmitamide or stearyl erucamide.