Study On Measurement And Characterization Of Glass Bleads Filled Polymer Composite With In-line Ultrasonic

Filling is one of important polymer modification methods. Particles volume fractions and their dispersions are two critical parameters, which have great influence on the performance of materials and quality of products. Therefore, developing the technique and device for measuring those two factors in real-time is necessary. In this thesis, in-line ultrasonic monitoring technique was developed and used to measure accurate particles volume fractions during the process of filling modification. The influencing factors of ultrasonic parameters was studied. It was expected to build accurate prediction models for particles volume fractions with few experiment. This study will contribute to optimize the ultrasonic propagation theory for particle/polymer melt and facilitate the application of non-destructive ultrasonic measuring technique in the field of polymer modification production.Firstly, in-line ultrasonic measuring system was developed for polymer processing, which can work at the temperature of 250°C and pressure of 20 MPa. LDPE and PS were chosen to study the effects of temperature, pressure and apparent shear viscosity on the velocity, attenuation coefficient of neat melts. Then, orthogonal experiment was designed using four factors(temperature, pressure, particles volume fraction and particle size) to analyze their effects on in-line measuring. Finally, taking temperature and pressure into consideration, quantitative models for particle volume fraction were built based on the attenuation coefficients. The prediction accuracy and adaptability of those models were validated under four kinds of processing conditions.The results suggested,(1) Both LDPE and PS can be used for in-line ultrasonic measuring within the range of common processing temperature. The effect of low shear flow on measuring can be ignored.(2) During the extrusion of low volume fraction system, the main influencing factors of velocity are temperature and pressure, while that of attenuation coefficient is particles volume fraction. So attenuation coefficient is applicable to measure particles volume fraction.(3) At constant temperature and pressure, quantitative model exhibits prediction relative errors value less than 0.4%. The adaptability of model based on data measured at higher temperature and pressure or different condition will improve. This thesis yielded a relatively accurate method for measuring the velocity and attenuation coefficient of neat melts as well as prediction model for particle volume fraction. The effective approaches to improve the adaptability of model to temperature variation were also provided.