Application of ultrasound and neural networks in the determination of filler dispersion during polymer extrusion processes

Abstract

Mineral filler dispersion is important information for the production of mineral‐charged polymers. In order to achieve timely control of product quality, a technique capable of providing real‐time information on filler dispersion is highly desirable. In this work, ultrasound, temperature, and pressure sensors as well as an amperemeter of the extruder motor drive were used to monitor the extrusion of mineral‐filled polymers under various experimental conditions in terms of filler type, filler concentration, feeding rate, screw rotation speed, and barrel temperature. Then, neural network relationships were established among the filler dispersion index and three categories of variables, namely, control variables of the extruder, extruder‐dependent measured variables, and extruder‐independent measured variables (based on ultrasonic measurement). Of the three categories of variables, the process control variables and extruder‐independent ultrasonically measured variables performed best in inferring the dispersion index through a neural network model. While the neural network model based on control variables could help determine the optimal experimental conditions to achieve a dispersion index, the extruder‐independent network model based on ultrasonic measurement is suitable for in‐line measurement of the quality of dispersion. This study has demonstrated the feasibility of using ultrasound and neural networks for in‐line monitoring of dispersion during extrusion processes of mineral‐charged polymers. POLYM. ENG. SCI., 45:764–772, 2005. © 2005 Society of Plastics Engineers

Recent Prospects in the Inline Monitoring of Nanocomposites and Nanocoatings by Optical Technologies

“…As an indirect technique requiring calibration or artificial intelligence-based models instead of being properly a real-time monitoring technique, ultrasonic spectroscopy has been shown to be an efficient way to predict the dispersion of micro- and nano-fillers in the extruder as a function of process parameters [57,58,59], based on the monitoring of velocity and the attenuation of ultrasound in the flowing material. In the case of nanoclays in a low-density Polyethylene (LDPE) matrix, in-process ultrasonic measurements across melt flow in the extruder die were shown to provide a viable indication of dispersion levels, although the relationships between measured signals and morphology were complex and warranted further investigation [60].…”

Degree of dispersion of polymeric compounds determined with terahertz time‐domain spectroscopy

“…In ultrasonic spectroscopy, longitudinal waves with frequencies between 1 and 50 MHz are used [29, 49]. The speed of sound in plastic melts is around 1000 m s −1 [27, 55]. In terahertz spectroscopy the frequency range spans around 0.1–3 THz and the group velocity of the electromagnetic pulse in polymers is ∼200,000 km s −1 .…”

“…In most cases, the experimental determination of the dispersion degree has been carried out on carbon black [1, 4, 5, 9] and calcium carbonate [2, 8, 11, 13–16, 22, 23, 25–28] filled materials. Glass beads have also been used due to their well defined form and size distribution [29, 30].…”

“…With those techniques, laborious sample preparation is not necessary. Ultrasonic spectroscopy has already been employed several times to determine the particle size distribution [26–28]. In process monitoring, two‐dimensional photometric measuring techniques [30–32] constitute the equivalent of offline microscopy tests.…”

Enhanced flow behaviors of metallocene‐catalyzed linear low‐density polyethylene during ultrasound‐assisted extrusion

“…All above are some traditional methods used to improve flow instability before and during the processing. In recent years, ultrasound technology has been developed to improve the processing properties of polymers during the extrusion [19–23]. In our laboratory, different kinds of polyethylene melts such as HDPE, LLDPE, and metallocene‐catalyzed linear low‐density polyethylene (mLLDPE), have been studied during ultrasound‐assisted extrusion [24–28].…”