Starch with paraformaldehyde

Starch is subject to fermentation by many microorganisms and, unless the mud is saturated with salt or the pH is >11.5, a preservative or biocide must be added if the mud is to be used for an extended period of time. The most common biocide until the mid-1980s was paraformaldehyde [9002-81-7]. This material has been largely replaced by isothia2olones (at 5—10 ppm cone) (74), carbamates, and glutaraldehyde [111-30-8]. Alternatively, the biocide may be incorporated during the processing of the starch and is present in the commercial product. 

All these materials produced intumescence to some degree, but only a few showed enough to be of real value. The most effective was a combination of paraformaldehyde, urea, and ammonium phosphate. This confirms the work of Jones and Soll(J.). The combination of isano oil with polyamide resin gave best results in exterior paint formulations. Amino acetic acid with starch and also with ammonium phosphate gave good results. 

Anionic graft-polymerization of paraformaldehyde onto starch and dextrin has been effected in methyl sulfoxide solution, polymerization being initiated by the carbohydrate potassium alcoholate formed from the reaction of the carbohydrate with naphthalene potassium, a metallation procedure not previously described for carbohydrates.220... 

As a preservative for industrial fluids, formaldehyde (formalin and paraformaldehyde) is preferably used in cosmetic products and in polymer dispersions (natural and synthetic latex) often in combination with other microbicides. Formaldehyde is listed in the EC list of preservatives allowed for the in-can protection of cosmetics (maximum authorized concentration 0.2%, except for products for oral hygiene 0.1%, prohibited in aerosol dispensers). Percentage of use in US cosmetic formulations 0.11% paraformaldehyde. Oil, fat and wax emulsions, starch and dextrine glues, adhesive dispersions, pigment and filler slurries, thickening solutions and other aqueous formulations containing no proteins can be preserved by the addition of formaldehyde, too in order to... 

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