Compounds that can be produced by a ring-opening reaction of epoxidized alkanes or epoxidized fatty acid esters having a molecular weight greater than 200 grams per mole are blended with polar polymers to improve the gloss of the polar polymers. These compounds include at least one polar functional group and are blended with polar polymers, or blends comprising at least one polar polymer, in order to improve the gloss of these polymers, such that they have suitable gloss right out of the manufacturing operation without the need for further painting or lamination steps. These compounds may also improve the impact strength of the polar polymers. Also disclosed are composite structures wherein an outer cap layer is made from the polar polymer blended with the gloss improving additive.