Monsanto Company

Edwin W Folk

Donald Joseph Stookey

George Palethorpe

Charles Nelson Carpenter

Arthur A Armstrong

Gerd R Baur

Robert L Voges

The method of recovering unreacted mono-olefinic monomers from an acrylonitrile polymerization slurry containing 30 to 50 weight percent of polymer solids and 70 to 50 weight percent of unreacted monomers wherein the slurry is first diluted with a solvent for the polymer and then fed in series through first and second treatment zones, with each of the treatment zones having a first stage for mixing the slurry with a solvent in vapor form to vaporize some of the unreacted monomers from the slurry and form a polymer solution and a second stage for separating monomer vapors from the liquid polymer solution. Fresh solvent, in vapor form and at an elevated temperature is supplied to the mixing stage of the second treatment zone and the vaporized solvent and unreacted monomers from the separation stage of the second treatment zone are fed to the mixing stage of the first treatment zone. The preferred ratio of solvent to slurry being fed to the mixing stages is 0.8 to 1.2. The polymer solution leaving the separation stage of the second treatment zone has a very low content of unreacted monomers.

Process for removing unreacted monomers from polymerization slurries

Method for making substantially void-free fibers having improved abrasion resistance wherein a spinning dope is formed by dissolving a dry acrylonitrile-containing polymer in a solvent/water mixture to form a spin dope which is wet spun at a temperature within the range of about 40.degree.C to about 75.degree.C. More specifically, the dope will contain from about 20 to about 28 weight percent of the polymer dissolved in a solvent containing about 1 to 8 weight percent water, based on the weight of the dope, with the solvent and water being mixed prior to contact with the polymer. The presence of water in the solvent brings about an improvement of the filamentary gel structure which results in fibers having enhanced durability and abrasion resistance.

Method for making void-free acrylic fibers

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Cary, NC, United States of America

Edwin W Folk