Study On Measurement Method Of Key Physical Parameters In Polymer And Its Composites With In-line Ultrasonic

The physical properties of polymers in polymer processing have an important influence on the final performance of the products.The physical parameters of different polymer systems often are tested to evaluate material properties with off-line method,however,because of disadvantages of cost and time-consuming,hysteretic information feedback,off-line test can not meet the current demand for continuous industrial production.Ultrasonic measurement technology has the advantages of high real-time and high sensitivity,so the paper applies inline ultrasonic measurement to testing key physical parameters of different polymer systems.In this paper,the precise measurement method of the physical parameters of different polymer system was established to reveal the inner relation between the ultrasonic signal and the physical parameters and to improve the scope of application of ultrasonic measurement in polymer processing industry,which is of scientific and practical significance to promote the inline ultrasonic measurement technology applied in polymer processing industry.First,in the aspect of hardware design,ultrasonic acoustic signal of different assembly mode was simulated through software WAVE 2000?,ultrasonic signal intensity and the difficulty of processing integrated,the new in-line ultrasonic transducer was researched and designed to be applied in testing environment of polymer processing for a long time,and the transmission performance and stability performance of ultrasonic acoustic sensor were verified and evaluated in different temperature.Then through the designed ultrasonic transducer as the core,ultrasonic measurement and characterization of the key physical parameters of different polymer system that density of pure polymer melt system and volume content of filled polymer system were performed,and according to the corresponding measurement results,results showed that:(1)Epoxy resin layer coated on carbon core material as a wave guide rod,effectively improved the signal-to-noise ratio of the wave guided rod,and the developed ultrasonic transducer based on the results,remains excellent acoustic stability and high signalto-noise ratio under the extreme conditions(260?,20MPa).(2)The density measurement method based on acoustic impedance model was established with the self-developed ultrasonic transducer as the core.For the pure melt as one component,the measurement results had good accuracy and precision,the maximum uncertainty which was used to characterize the accuracy was 0.003g/cm3;for the pure melt as two component,ultrasonic measurement results deviated the theoretical linear density seriously,the density deviation degree increased first and then decreased as component increased,which related to the change of uniformity with the polymer.(3)For polymer filling system,the parameter S1 could be used to characterize the volume content of glass beads in glass bead particles filled polymer composites,and comparing the two order model and exponential attenuation model,the two order model could reflect the relationship between the changes of the volume fraction and the acoustic characteristic parameters of S1.In the base of two order measurement model,the correcting model in consideration of processing factors such as temperature and pressure was proposed,showed better prediction ability,the highest predicted content t error was 1.04%,the lowest predicted content error was only 0.10%.