In-line monitoring of molten polymeric processes

The principle of total quality management is the cornerstone of the success of any organization in today's competitive environment. There has been a tangible upheaval in process technology, and in-line process monitoring techniques are being promoted in all quarters, as a consequence. This current surge in interest in in-line process monitoring has had a resounding effect on the polymer industries. Near infrared spectroscopy, coupled with fiber optics, is rapidly emerging as an in-line monitoring technique for molten polymers, during plastics manufacturing. In-line monitoring is not only desired for its numerous advantages, (such as high quality products, lower waste, lower developmental cycle time, and lower costs), but also because it eliminates the sample handling concerns associated with molten polymeric processes.

A big constraint in the application of this technique has been the unavailability of rugged probes that could withstand the severe conditions encountered in molten polymeric processes, i.e. high temperatures, high pressures, and harsh chemical environment. In this research, a series of rugged probes was designed and evaluated. The probes were tested using a polymeric system of blends of polystyrene and polyphenylene oxide. Finally, a thorough study of a system of poly(ethylene vinyl acetate) (EVA) random copolymers was performed. Rigorous multivariate analysis was used to develop robust calibration models for quantification of vinyl acetate (VA) concentration. The calibration models were also used to demonstrate real-time monitoring of VA concentrations. Also, the performance of near infrared spectroscopy for quantification of trace level additives in EVA copolymers was studied.