Optics: measuring and testing – By shade or color
Patent
1990-11-01
1991-11-05
Evans, F. L.
Optics: measuring and testing
By shade or color
356416, 356419, 356414, G01I 346, G01N 2125, G01J 342
Patent
active
050627139
ABSTRACT:
A method for the on-line determination of the residence time distribution of a polymer extruder by injecting a quantity of dye, such as Mobay Red 5B, into the feed throat of the extruder and then photometrically monitoring the polymer flowing from the extruder for the dye. The advance of the present invention is to direct a single beam of polychromatic light through the polymer flowing from the extruder, e.g., by using a quartz-halogen light source and an optical fiber, and then to split this single beam of light that has passed through the polymer into two beams, e.g., by the use of a bifurcated optical fiber, each of which resulting beams are then passed through a separate filter to a separate photodetector. The wavelength of maximum transmission of one of the filters is selected to be near the wavelength of maximum light absorption of the dye so that the signal from the photodetector associated with this filter is a function of the concentration of the dye in the polymer flowing from the extruder. The wavelength of maximum transmission of the other filter is selected to be near the wavelength of minimum light adsorption of the dye and the polymer so that the signal from the photodetector associated with this filter is a function of the background light absorption of the polymer flowing from the extruder. The noise level of the dye concentration signal can be a problem due to bubbles and inclusions in the polymer flowing from the extruder and this noise level is substantially reduced by correcting the dye concentration signal with the background signal.
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patent: 4464054 (1984-08-01), Karras et al.
Farquharson et al; "Extruder Mixing Analysis via a Fiber Optically Coupled Visible Spectraphotometer", Chemical, Biochemical and Environmental Applications of Fibers, 990, 1988.
Delahay, Instrumental Analysis, 5th Printing, pp. 215-216, 1967.
Skoog et al; Fundamentals of Analytical Chemistry, pp. 663-664, 1963.
David B. Todd, Residence Time Distribution in Twin-Screw Extruders, Polymer Engineering and Science, 15(6), 437-443 (1975).
Farquharson Stuart
Keillor, III Peter T.
Evans F. L.
Hantis K. P.
Stevens Timothy S.
The Dow Company
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