Study Of On-Line Rheological Measurement For Injection Molding

Rheological parameters play a very important role in the polymer processing industries. By the rheological measurement, the polymer processing could be optimized and the quality of the end-products could be improved as well. Injection molding is one of the most important ways of polymer processing. However, because of its unique characteristics of periodicity and clipping molding, the rheological parameters gained from the traditional capillary rheometer could not meet the needs of injection molding. To obtain more reliable polymeric rheological parameters in injection processing, a new on-line rheological measurement for injection molding had been developed.In this study, the polymer melt was plasticized by the plasticizing system of injection molding machine, and then was purged into the on-line rheometer for real-time measurement. The research work had been developed in the following areas:1. By analyzing the rheological properties of polymer based on the plasticizing and forcing process, and with the comparison of the properties and measuring principle among all kinds of rheometers, a method of on-line rheological measurement for injection molding had been put forth.2. Base on the configuration and the principle of the traditional rheometer, and according to the rheological parameters of different polymer gained from the lab capillary rheometer with different temperatures and capillaries, a new on-line rheometer for injection molding had been developed in this work. Compared with the traditional rheometer, the new one had been ameliorated in the following two aspects. On the one hand, the melt for rheological measurement was directly supplied by the injection molding machine, which could ensure the reality of the test condition. On the other hand, the transmission mode of servomotor driving ballscrew was adopted, which could realize the accurate rheological measurement of the polymer with continuously changed share rate. The new rheometer is an integrative testing equipment. Because of its advantages of rapid responding time, wide range of share rate and high measurement precision, it could not only be used in steady measurement, but also in unsteady measurement.3. Several share rate testing modes were set, and as for each mode, the demands on control and signal acquisition frequency had been put forward. Finally, a flow diagram of testing progress had been provided.