Application of low-resolution Raman spectroscopy to online monitoring of miniemulsion polymerization

Raman spectroscopy has become a preferred technique for online monitoring of dispersion polymerization. Raman spectroscopy offers two specific advantages for these systems, First, it is insensitive to the presence of water, and the total amount of water in the emulsion has little to no influence. Second, it can use standard glass fiber conduits combined with a visible light excitation laser to allow use of a flexible remote sensor. A low-cost low-resolution Raman spectrometer (LRRS) was used to monitor emulsion polymerization, specifically batch miniemulsion polymerization. Styrene was used as an internal reference to compensate for the effect of laser intensity fluctuation. A linear correlation between peak intensity ratio and monomer concentration was found. Probe fouling was controlled by using a protective film with minimal impact on measurement quality. (C) 2002 Wiley Periodicals, Inc.