In-line measurement of additive and pigment loadings in molten polymer systems by fiber optic spectroscopy

This project further developed in-line spectroscopic measurements for molten polymer systems. There are two main focuses: development of an online technique for the determination of concentration of ultraviolet stabilizers and antioxidant additives in polypropylene at orders of magnitude higher than those previously studied, and the development of a practical on-line color measurement technique.; Off-line quality control techniques have a lag period before changes to the operating conditions can be made. Development of on-line measurement techniques not only provides a real time indication of the operating conditions, but is the fundamental element missing in the development of a real time, feedback control system of the manufacturing process. The development of fiber optic cable allowed for traditional laboratory techniques to be applied in the production area of chemical processing facilities. The use of this type of cable has allowed the development of online techniques using near infrared (NIR), Fourier transform infrared (FTIR), ultraviolet (UV), and Raman spectroscopy.; The objective of the additive portion is to determine a spectroscopic technique or combination of techniques to determine the amount of additives contained in the sample. Research was conducted to investigate the effect of additive loading on the polymer's rheological properties. These results are correlated back to the spectroscopic data to develop an on-line measurement of the viscosity or melt index of the material. The sample additives are compounded with an unmodified polypropylene resin. Research focused at determining the best spectroscopic technique utilizing NIR or UV methods as well as the optimal mathematical regression to provide the most accurate measurement of the additive concentration.; The color objectives are to investigate several commonly used pigments in the plastics industry and develop a spectroscopic technique to determine the pigment concentration. If the pigment is treated like another additive, it is possible to correlate the specification material to the color standard. Once the correct pigment loading is established, online measurement will indicate off-specification material. This project investigated the different spectroscopic techniques currently available to determine the optimum method for measuring concentration, as well as the proper mathematical regression technique for the most accurate concentration measurements.