Dow Corning Corporation

Neal Roger Langley

James A Rabe

Jonathan Lipowitz

Gary N Bokerman

Chi-Tang Li

David Charles Deleeuw

Harvey A Freeman

The yield stress of rheologically plastic fluids such as coatings, sealants, and personal care lotions, determines their tendency to flow at low gravitational stress. Yield Stress is the apparent threshold stress above which flow is observed on an arbitrary time scale. An on-line technique to monitor yield stress during processing was developed, and can be used in controlling the slump or non-slump behavior of such products. A residual stress, after a flow excursion returns to zero shear rate, is related to yield stress. This residual stress can be used for process monitoring. It is measured from the residual pressure or torque after a controlled strain rheometer reaches zero strain rate.

Method of measuring yield stress

The present invention relates to ceramic fibers of the Si-C-N-O series with a diameter less than about 20 micrometers. It has been unexpectedly found that the thermal stability of these fibers can be increased by minimizing the impurity content, primarily the content of metals or metallic compounds. Such fibers with low levels of contaminants retain greater than about 60 percent of their initial tensile strength when subjected to temperatures of 1300.degree.-1400.degree. C. for at least 30 minutes in a non-oxidative environment.

Polymer derived ceramic fibers having improved thermal stability

A method of polymerizing hydroxyl-endblocked polydiorganosiloxane in the presence of filler, including acidic filler such as fumed silica, through the use of basic diorganosilanolates as catalysts is claimed. Preferred diorganosilanolates are tetra-n-butylphosphonium dimethylsilanolate and potassium dimethylsilanolate. The silicone polymer-filler mixture produced is useful in silicone greases and elastomers. Methods of combining the silicone polymer-filler mixture with various curing agents to yield curable compositions are claimed.

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Midland, MI, United States of America

Neal Roger Langley