Abstract: A process for preparing a polymer from a 3-hydroxy carboxylic acid as monomer comprising at least 8 carbon atoms where the polymerisation reaction is conducted at a temperature of from 100° C. to 180° C. while removing water from the reaction mixture, wherein 50 to 100 mol-% of the monomers used are 3-hydroxy carboxylic acids comprising at least 8 carbon atoms. A polymer comprising units based on 3-hydroxy carboxylic acid, comprising at least 8 carbon atoms, characterized in that of from 60 to 100 mol-% of the units are based on beta-hydroxy carboxylic acids, comprising at least 8 carbon atoms and films, foils, flexible packaging, and barrier coatings comprised of said polymers.