Polymer extrusion and cure monitoring using clad polymer buffer rods

Ultrasonic clad polymer buffer rod sensors were used for in-line monitoring of polymer extrusion and cure of polyester resins. For extrusion monitoring, this buffer rod was inserted into the barrel of an extruder. The results showed that this probe together with a fast data acquisition system was able to detect the change of polymer properties caused by the injection of a tracer into the extruded polymer. Thus we can in-line monitor the polymer residence time distribution inside the barrel, which is a crucial parameter for industrial extruders. Ultrasonic monitoring of the cure process of polyester resins was also performed. With our technique, the reflection coefficient at the sensor/polymer interface, as well as the sound speed and acoustic attenuation coefficient inside the polymer during cure were obtained for both longitudinal and shear waves