IN-LINE MONITORING OF MOLTEN POLYMERS - NEAR-INFRARED SPECTROSCOPY, ROBUST PROBES, AND RAPID DATA-ANALYSIS

The concept of improved product quality and reduced costs has revoluti onized analytical techniques in the polymer industry. It has brought i n-line analysis to the forefront, with near infrared (NIR) spectroscop y proving to be a very viable technique for such operations. A system for continuous in-line near infrared monitoring of molten polymer blen ds, copolymers, and polymer reactions is being developed. The ultimate objective is to use this monitoring system to develop feedback contro l for polymeric processes. Experiments on blends of polystyrene and po ly(phenylene oxide) have been performed by using a flow cell, located at the exit port of a single-screw extruder. Qualitative analysis of s pectral data has been substantiated by a variety of quantitative (mult ivariate) techniques. Robust calibration models, suitable for on-line predictions, have been developed. The success of in-line process analy sis depends on the performance of fiber-optic probes that are inserted into the process stream. These probes normally succumb to the demands of the rigorous process environment, typical of polymeric processes, i.e., high temperatures, high pressures, and adverse chemical conditio ns. Design and development of fiber-optic probes that are capable of w ithstanding such harsh conditions have also been undertaken. Results w ill be reported on the polymeric systems and optical probes.