Controlling moisture in and plasticization of bioresorbable polymer for melt processing

A system for fabricating a stent, the system comprising:

• a resin hopper for holding polymer resin, the resin hopper comprising a resin outlet port for connecting to an extruder and the resin hopper used for feeding polymer resin through the resin outlet port to the extruder;
• a control loop comprising the resin hopper, a drier unit, a conduit for carrying a drying gas stream from the drier unit for input into a gas inlet port of the resin hopper and a conduit for carrying the drying gas stream after exiting through a gas outlet port in the resin hopper to the drier unit, wherein the drier unit removes moisture from the drying gas stream that exits from the resin hopper;
• a source of a moist gas stream outside the control loop and a conduit for carrying the moist gas stream from the moist gas stream source to inject the moist gas stream into the drying gas stream from the drier unit to form the drying gas stream for input into the resin hopper, wherein a moisture content of the moist gas stream provided by the source outside of the control loop is higher than a moisture content of the drying gas stream from the drier unit;
• and wherein the source of the moist gas stream comprises a humidity conditioning unit configured to generate a gas stream with selected temperature and humidity from a dry gas stream source;
• at least one humidity sensor to monitor moisture content of the drying gas stream;
• and
• a controller that generates a signal to adjust the moisture content of the drying gas stream for input into the resin hopper upward or downward based on the monitored moisture content.