Research On Signal Processing Technology For Represent Polymer Compounding State

Polymer compounding using a screw extruder is a widely used process. Adding fillers such as inorganic particles or organic material in the polymer, the impact strength, tensile strength, hardness and other performance will be greatly improved and the uses more widely. The mixed state of polymer and filler in extrusion has a great influence on the performance of the composite material products. So it is significant to monitoring the state of polymer in extrusion machine.To study the extraction of the feature parameter which used the ultrasonic method to test the state of polymer, the paper analyzing the relationship between ultrasonic parameters and the state of polymer. In allusion to the trailing-wave disturbances existed in the acquisition signals of sensors, a modified scheme on an ultrasonic sensor is proposed, in which the structure and installation location of the sensor was optimized and experimented. According to the periodic variation tendency of the screw rotation, the signal processing method has been explored for a pattern matching. In each cycle, the amplitude deviation of the ultrasonic echo wave at the same detection positions was selected as the characteristic quantity, by which the mixedness degrees of the polymers were investigated. Moreover, based on the differences of the ultrasonic echo and distance attenuations among different screw structures, the signal processing method on the screw structure was studied, by which the effects of the variation of the screw structure on the ultrasonic attenuation coefficient were revised, and the mixedness degrees of the polymer were characterized. By making experiment of LDPE and filler mixed in Φ>20single screw extrusion machine, the effectiveness of the above two methods are investigated. The thesis research on ultrasonic testing technology laid a theoretical basis for the state of the polymer blends widely used in production practice.