Infrared polymerization index

IRPI infrared polymerization index JUSE Japanese Union of Science and Engi-... 

Infrared Polymerization Index n (IRPI) A number representing the degree of cure of phenolic resins, defined as the ratio of absorbances by the sample, corrected for background absorbance, at wavelengths of 12.2 and 9.8 pm (far infrared). The test is often used in conjunction with the Marquardt Index. 

In the wine industry, FTIR has become a useful technique for rapid analysis of industrial-grade glycerol adulteration, polymeric mannose, organic acids, and varietal authenticity. Urbano Cuadrado et al. (2005) studied the applicability of spectroscopic techniques in the near- and mid-infrared frequencies to determine multiple wine parameters alcoholic degree, volumic mass, total acidity, total polyphenol index, glycerol, and total sulfur dioxide in a much more efficient approach than standard and reference methods in terms of time, reagent, and operation errors. 

Low variation (almost constant value) of the refractive index of polymeric and hybrid materials in the range from infrared to microwave region ensures a proper work operation of the modulator over the whole spectral range ... 

One of the issues when monitoring an emulsion polymerization reactor is selection of the most appropriate technique [124, 126]. For instance, monomer conversion and copolymer composition can be monitored on-line by means of densim-etry, refractive index, gas chromatography, calorimetry, ultrasound, fluorescence, ultraviolet reflection, and other spectroscopic methods such as Raman, mid-range infrared, and near-infrared. 

If the sample has a smooth, planar surface so that good physical contact with an infrared-transparent, higher refractive index prism/plate may be achieved, it can be examined by an infrared reflection technique, for example, one using attenuated total reflection, multiple internal reflection. It should be borne in mind, when examining polymeric films, that the sample may be a laminate and hence examination may give very different spectra from reflection at the two surfaces and also from transmission techniques. A coating or paint may be directly applied to a transparent plate for transmission or reflection techniques. 

By making use of infrared, the pathlength of a liquid cell may be determined by measurement of the interference pattern observed. In the same way, the interference pattern often observed in the infrared spectra of thin polymeric films may be used to determine the thickness of the film. A knowledge of the refractive index of the polymer is required for this determination. If the incidence of the radiation is not normal then the angle of incidence is also required, see the equation below. 

Reed and coworkers developed a strategy for automatic continuous online monitoring of polymerization (ACOMP). The method may be used during the initial development of the polymerization process, its optimization and monitoring of the continuous reaction. ACOMP automatically dilutes samples from the reactor and measures its properties, e.g., refractive index, near infrared (NIR) spectra, LSc, [ ]], etc., from which it computes evolution of MW, MWD, degree of conversion, copolymer composition (in copolymerization) and others. The method has been applied to a variety of the free radical homo- and co-polymerizations, including the reactions in emulsion or suspension. ... 

The resulting polymer sheets were characterized by determination of the refractive index (10) and density (11). The uncorrected difference between the monomer and polymer specific gravity was taken as the polymerization shrinkage. Using the method of Loshaek and Fox (12) the percentage utilization of unsaturation was calculated from volume contraction based on the assumption of 23.0 cc change in volume per mole of double bonds. The percent of residual double bonds in the sheets was also determined by attenuated total reflectance infrared spectroscopy using a Perkin-Elmer Model 137-D Infracord Spectrophotometer and Buck Scientific Universal Reflectance Unit URU-101. 

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