Straw, Rice Hulls, Buckwheat Husk Cellulose Preparation Of Superabsorbents

Super water absorbent resin(SWAR) has unique water absorbability and water capacity. The superior properties of SWAR make it widely used in numerous fields, especially in agriculture, forestry, horticulture and medicine. Cellulose is the most abundant natural polymer in nature. Since it has the properties of innocuity, easy obtainable, biodegradable and nonpollution, the development of cellulose product become the focus of study recently. The synthesized cellulose SWAR is very important for the purpose of fully utilizing of natural resources and reducing pollution. While cellulose is coming from abandoned agriculture products such us rice husk, wheat-straw and buckwheat shell. Thus the following work was done in seven aspects and the study was focused on soft polyurethane foam modified by cellulose-acrylic acid graft resin.1. The study of carboxymethyl cellulose (CMC) water absorbentThe cellulose extracted from rice husk was treated with diluted hydrogen nitrate and then alkali. Carboxymethyl cellulose water absorbent was prepared from cellulose obtained above. There are two methods of synthesizing CMC. The one was first cross-linking and then etherification, the other was first etherification and then cross-linking. The optimal synthesis method was obtained by comparison of these two methods. The various influencing factors were also discussed. It demonstrated that water absorbent resign prepared by rice husk cellulose showed better water absorbability and water capacity when 2,4,6-trichloropyrimidine was used as crosslinker. The water absorbability and salt absorbability of resin synthesized under this condition are 54(g/g) and 27(g/g).2. The study of cellulose-acrylic acid graft water absorbentThe cellulose-acrylic acid graft water absorbent was prepared by inverse suspension polymerization, inverse emulsion polymerization and solution method. The various influencing factors were discussed. It demonstrated that water absorbent prepared by rice husk cellulose through inverse suspension polymerization showed better water absorbability. The water absorbability and salt absorbability of resin synthesized under this condition are 1712(g/g) and 163(g/g).3. The study of cellulose-acrylamide graft water absorbentThe cellulose-acrylamide graft water absorbent was prepared by graft copolymerization and graft copolymer alkali hydrolyzation method. The various influencing factors were discussed. It demonstrated that water absorbent prepared by CMC showed better water absorbability when 0.2-0.3% N,N'-methylenediacrylamidewas used as crosslinker. The water absorbability and salt absorbability of resin synthesized under this condition are 1051(g/g) and 123(g/g).4. The study of CMC-acrylic acid-acrylamide graft water absorbentThe water absorbent resin was prepared by graft copolymerization of CMC-acrylic acid-acrylamide. The various influencing factors were discussed. It demonstrated that the optimal conditions of the polymerization were in the following: the quantity of initiator ammonium persulfate was 1% -2% CMC, the quantity of crosslinker 7V,jV-methylenediacrylamide was 0.2% -0.3%monomer, the neutralization value of acrylic acid was 60%-70%, and polymerization temperature was 50°C-60°C. The results showed that the water absorbability and the salt absorbability of resin synthesized under this condition are 1294(g/g) and 157(g/g).5. The study of soft polyurethane foam modified by cellulose-acrylic acid graft water absorbentA kind of soft super water absorbent resin was prepared by adding cellulose-acrylic acid graft water absorbent to soft polyurethane foam shaping process. The factors of isocyanate indexes and the time of adding cellulose-acrylic acid graft water absorbent influencing resin properties were studied. It demonstrated that the optimal conditions of the polymerization were in the following: isocyanate indexes was 1.0-1.2, the quantity of cellulose-acrylic acid graft water absorbent was 20-30 pre 100 polyether, and the time of adding was 15s-18s in foam shaping process. The results showed that the water absorbability of resin synthesized under this condition was 58(g/g). It can be used in forming flat piece and abnormal shape, thus it have wide application prospects in medicine for these advantages.6. Preparation of polyurethane foam by adding rice hullRice hull was added into polyurethane foam system when molded, and the polyurethane foam material was synthesized. The preparation conditions and degradation in natural were studied. It demonstrated that the degradation rate of polyurethane foam with rice hull added was obviously higher than the one without rice hull.7. Preparation of biodegradation materials by crosslinking of rice hull fiber and isocyanateRice hull fiber was crosslinked by toluene-2,4-diisocyanate in DMAc/LiCl homogeneous phase system, and a new type of biodegradation fiber film was prepared in this way.