The present invention provides thermoplastic hydroxy-functional polyesters. The polyesters have at least 10 sequential units, wherein the sequential units consist of units selected from units represented by the following formula (1) and units represented by the following formula (2); Wherein each of R.sup.1 independently represents hydrogen or a substituted or unsubstituted homoalkyl or heteroalkyl group; each of R.sup.2 independently represents hydrogen or a substituted or unsubstituted homoalkyl or heteroalkyl group; each of R.sup.3 independently represents hydrogen or a substituted or unsubstituted homoalkyl or heteroalkyl group; Each of R.sup.4 independently represents a substituted or unsubstituted homoalkyl or heteroalkyl group; and said moiety having no fewer than 1 unit represented by formula (1) and no fewer than 1 unit represented by formula (2). The present invention further provides processes for making hydroxyfunctional polyesters, such as polymerizing epoxidized fatty acids in the presence of an onium salt, and compositions and articles that include or are derived from the hydroxyfuntional polyesters ##STR00001##