Apparatus for infrared laser spectroscopy of room temperature vulcanizable silicone compositions

Apparatus for monitoring the crosslinker content of a room temperature vulcanizable silicone composition process stream comprising:

• (a) means for continuously bypassing a portion of said stream to a sample detection region, dividing said portion into first and second parts, and diverting said first part from said sample detection region;
• (b) a sample cell comprising a pair of opposed infrared transparent windows extending in parallel planes wherein the space between said windows is adjusted upon consideration of the relative viscosity of said room temperature vulcanizable silicone composition flowing in said process stream;
• (c) means for diverting said second part through said sample cell between said windows;
• (d) a laser effective for directing a beam of infrared radiation maintainable at a predetermined frequency corresponding to a selected infrared absorption frequency of the crosslinking agent contained in said process stream and at a power intensity effective to overcome the characteristic infrared opacity of said second part of said stream when filling the space between said windows, through said windows of said sample cell and through said second part of the RTV process stream flowing therebetween;
• and
• (e) means for continuously detecting the proportion of said infrared radiation when said radiation is absorbed by said second part of said sample cell at said predetermined frequency at said effective intensity.

Apparatus for continuous analysis and control of a manufacturing process comprising:

• (a) means for individually containing a plurality of predetermined starting materials;
• (b) means for regulating the flow of said starting materials into a processor;
• (c) a conduit for directing a process stream from said processor to a receptacle;
• (d) means for diverting a sample of said process stream to a sample detection region;
• (e) means for irradiating said sample with infrared radiation directed through said detection region, wherein said radiation is adjusted to a frequency of infrared absorption corresponding to a characteristic absorption frequency of one of said starting materials, and wherein the power intensity of the radiation is sufficient to overcome the characteristic infrared opacity of said sample at a selected thickness and frequency;
• (f) a detector for determining infrared radiation absorbed by said sample;
• (g) means for detecting a continuous flow of said sample through said sample detection region and indicating any deviation from a predetermined flow rate through said region;
• and
• (h) a programmable means effective for interpreting absorption data, continuously storing said data, operating a trend recorder and controlling said means for regulating the flow of said starting materials.

A method for determining the concentration of a constituent in a process stream comprising the steps of:

• (a) bypassing a portion of said stream to a sample detection region;
• (b) splitting said portion of said stream into first and second parts and diverting said first part from the sample detection region;
• (c) diverting said second part of said stream through a sample region at a continuous thickness of approximately 0.010 inches to approximately 0.030 inches apart, said thickness being adjusted upon consideration of the relative viscosity of the stream flowing through said sample region;
• (d) directing a beam of infrared radiation maintainable at a predetermined frequency corresponding to a selected infrared absorption frequency of the constituent in the process stream under consideration, through said sample region and through said second part of the process stream flowing therethrough;
• and
• (e) continuously detecting the proportion of said infrared radiation at said predetermined frequency absorbed by said second part of said stream in said sample region.