Combination of NIR, Raman, ultrasonic and dielectric spectroscopy for in-line monitoring of the extrusion process

Determination of melt composition and/or morphology by fast, reliable and accurate in-line methods is highly desired in polymer industry. in-line spectroscopic methods like near infrared (NIR), Raman or ultrasonic spectroscopy are such reliable methods for process control without time consuming sampling and off-line analytics. As the number of in-line techniques available is increasing, it becomes increasingly difficult for manufacturers and plastic processors to choose the right method or combination of methods for their needs and to keep track of the growing amount of information. Therefore, we combined different in-line techniques in one slit die in order to compare their potential for various systems such as composites and blends. One installation consists of a combination of NIR and Raman spectroscopy, rheometry and ultrasonic measurements. Another installation bases on a slit die developed for rheology which was equipped with dielectric and ultrasonic sensors. The results of the applied in-line methods are compared and the specific advantages and drawbacks are discussed.