a method for producing trimethylene carbonate poly introducing liquid poly and an optional catalyst into a wiped film evaporator reactor under a vacuum about 15 kpa or less , said reactor having walls heated to at least about 230 ° c . and an internal condenser heated to a temperature above the boiling point of trimethylene carbonate , spreading the poly into a thin film and allowing it to flow down the interior surface of the heated walls , depolymerizing the poly to form trimethylene carbonate which is driven to the internal condenser and residue poly which continues down the reactor , and collecting the trimethylene carbonate in a cooled distillate receiver .