GRAFTED CROSSLINKED CELLULOSE
Grafted, crosslinked cellulosic materials include cellulose fibers and polymer chains composed of at least one monoethylenically unsaturated acid group-containing monomer (such as acrylic acid) grafted thereto, in which one or more of said cellulose fibers and said polymer chains are crosslinked (such as by intra-fiber chain-to-chain crosslinks). Some of such materials are characterized by a wet bulk of about 10.0-17.0 cm 3 /g, an IPRP value of about 1000 to 7700 cm 2 /MPa·sec, and/or a MAP value of about 7.0 to 38 cm H 2 O. Methods for producing such materials may include grafting polymer chains from a cellulosic substrate, followed by treating the grafted material with a crosslinking agent adapted to effect crosslinking of one or more of the cellulosic substrate or the polymer chains. Example crosslinking mechanisms include esterfication reactions, ionic reactions, and radical reactions, and example crosslinking agents include pentaerythritol, homopolymers of the graft species monomer, and hyperbranched polymers.
1 . A cellulosic material comprising a cellulose fiber and polymer chains composed of at least one monoethylenically unsaturated acid group-containing monomer grafted thereto, wherein one or more of said cellulose fiber and said polymer chains are intra-fiber crosslinked, and wherein at a given IPRP value (in cm 2 /MPa·sec) from 800 to 5400, the material has an MAP value (in cm H 2 O) higher than the corresponding MAP value possessed by non-grafted, crosslinked cellulose fiber.
2 . The material of claim 1 , wherein the at least one monoethylenically unsaturated acid group-containing monomer includes acrylic acid.
3 . The material of claim 1 , characterized by a graft yield of 5-35 weight %.
4 . The material of claim 3 , characterized by a graft yield of 10-20 weight %.
5 . The material of claim 1 , wherein the material has a wet bulk at least 6% greater than untreated cellulose fiber.
6 . The material of claim 1 , wherein the material has a wet bulk of about 10.0-17.0 cm 3 /g.
7 . The material of claim 1 , wherein the material has an IPRP value of about 1000 to 5400 cm 2 /MPa·sec and a MAP of about 8.0 to 20 cm H 2 O.
8 . The material of claim 1 , characterized in that at a given MAP value (in cm H 2 O) from 7.0 to 20, the material has an IPRP value that is equal to or higher than the corresponding IPRP value possessed by non-grafted, crosslinked cellulose fiber.
9 . A cellulosic material comprising a cellulose fiber and polymer chains composed of at least one monoethylenically unsaturated acid group-containing monomer grafted thereto, wherein one or more of said cellulose fiber and said polymer chains are intra-fiber crosslinked, and wherein at a given MAP value (in cm H 2 O) from 7.0 to 20, the material has an IPRP value (in cm 2 /MPa·sec) higher than the corresponding IPRP value possessed by non-grafted, crosslinked cellulose fiber.