The Influence of Extruder Residence Time Distribution On Polymer Degradation

The determination of the Residence Time Distribution (RTD) is impor tant in understanding polymer degradation during processing. Most polymers are temperature sensitive and will degrade with prolonged exposure to the high temper atures found in the extrusion process. This paper discusses a method where RTD can be estimated by introduction of a tracer into the process and measuring the response. The measurement of the RTD of Linear Low Density Polyethylene (LLDPE) in the blown film process has been determined for various operating conditions. Under standing the flow characteristics of the extruder and the die can help in controlling degradation and assisting in determination of better operating procedures.