Highly absorbent polymeric compositions derived from flour
AssigneeThe United States of America as represented by the Secretary of Agriculture
InventorsGeorge F. Fanta, William M. Doane
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Abstract
Absorbent polymeric compositions are prepared by graft polymerizing acrylonitrile onto flour or other starch-containing substrates and then subjecting the flour-polyacrylonitrile graft copolymers to alkaline saponification. Compositions prepared from gelatinized flour absorb from 1800-3000 times their weight of deionized water.
Claims10
A method of preparing water-insoluble, aqueous fluid-absorbing compositions comprising the following steps:
- a. graft polymerizing acrylontrile onto a starch-containing substrate to form a starch-containing substrate-polyacrylonitrile (SCS-PAN) graft copolymer, wherein said starch-containing substrate is selected from the group consisting of flours and meals, and wherein the weight ratio of said substrate to said acrylonitrile is in the range of 75:25 to 25:75;
- b. saponifying the SCS-PAN graft copolymer from step (a) in an aqueous slurry with an alkali in amounts such that the molar ratio of alkali to the acrylonitrile repeating unit of said SCS-PAN graft copolymer is from about 0.1:1 to about 7:1 to form a water-soluble saponified graft copolymer (SCS-HPAN);
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- c. drying said water-soluble SCS-HPAN from step (b) to a moisture level in the range of about 1 to 15% water by weight, whereby said SCS-HPAN is rendered water-insoluble.
Aqueous fluid-absorbing compositions comprising water-insoluble alkali salts of saponified starch-containing substrate-polyacrylonitrile (SCS-HPAN) graft copolymers, wherein said starch-containing substrate is selected from the group consisting of flours and meals, and wherein the weight ratio of said substrate to said acrylonitrile is in the range of 75:25 to 25:75, said SCS-HPAN graft copolymers being further characterized as water-insoluble solids capable of absorbing up to about 3000 parts of water by weight per part of said water-insoluble solids.
Dependencies are inferred from the claim text.