In this study, a series of chitosan-g-poly(acrylic acid)/vermiculite (CTS-g-PAA/VMT) superabsorbent composites containing VMT, acid-activated, ion-exchanged, and organic modified VMT were synthesized by free-radical graft polymerization in aqueous solution, using N,N’-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. The effects of VMT and modified VMT on equilibrium water absorbency, swelling rate, and swelling behavior in various cationic saline solutions (NaCl, CaCl2, and FeCl 3) and different pH value solution of superabsorbent composites were systematically investigated. FTIR spectroscopy confirmed that acrylic acid had been grafted onto CTS and the -OH groups of VMT participated reaction. The introduction of acid-activated, ion-exchanged, and organic modified VMT into chitosan-g-poly(acrylic acid) polymeric network could improve water absorbency and swelling rate compared with that of VMT. The water-absorbing capacity of superabsorbent composites decrease gradually with the increasing of the concentration of NaCl, CaCl2, and FeCl3 solutions from 0.01 to 10 mM. The all prepared samples have similar swelling behavior in different pH value solution and the equilibrium water absorbencies of samples keep roughly constant in the pH range from 4 to 12.
Buchholz, F.L. and Graham, A.T. ( 1998). Modern Superabsorbent Polymer Technology, Wiley-VCH, New York.
2.
Zohuriaan-Mehr, M.J. and Kabiri, K. (2008). Superabsorbent Polymer Materials: A Review, Iran. Polym. J., 17: 451-477.
3.
Mudiyanselage, T.K. and Neckers, D.C. (2008). Highly Absorbing Superabsorbent Polymer, J. Polym. Sci. Part A: Polym. Chem., 46: 1357-1364.
4.
Wu, J.H., Wei, Y.L., Lin, J.M. and Lin, S.B. ( 2003). Preparation of a Starch-Graft-Acrylamide/ Kaolinite Superabsorbent Composite and the Influence of the Hydrophilic Group on its Water Absorbency, Polym. Int., 52: 1909-1912.
5.
Lin, J.M. , Wu, J.H., Yang, Z.F. and Pu, M.L. (2001). Synthesis and Properties of Poly(Acrylic Acid)/Mica Superabsorbent Nanocomposite, Macromol. Rapid. Commun., 22: 422-424.
6.
Li, A., Wang, A.Q. and Chen, J.M. ( 2004). Studies on Poly(Acrylic Acid)/Attapulgite Superabsorbent Composite. I. Synthesis and Characterization, J. Appl. Polym. Sci., 92: 1596-1603.
7.
Zheng, Y.A., Li, P., Zhang, J.P. and Wang, A.Q. ( 2007). Study on Superabsorbent Composite XVI. Synthesis, Characterization and Swelling Behaviors of Poly (Sodium Acrylate)/Vermiculite Superabsorbent Composites, Eur. Polym. J., 43: 1691-1698.
8.
Santiago, F., Mucientes, A.E., Osorio, M. and Rivera, C. ( 2007). Preparation of Composites and Nanocomposites Based on Bentonite and Poly (Sodium Acrylate). Effect of Amount of Bentonite on the Swelling Behaviour, Eur. Polym. J., 43: 1-9.
9.
Zhang, F.Q., Guo, Z.J., Gao, H., Li, Y.C., Ren, L., Shi, L. and Wang, L.X. ( 2005). Synthesis and Properties of Sepiolite/Poly (Acrylic Acid-Coacrylamide) Nanocomposites, Polym. Bull., 55: 419-428.
10.
Qi, X.H. , Liu, M.Z., Chen, Z.B. and Liang, R. (2007). Preparation and Properties of Diatomite Composite Superabsorbent, Polym. Adv. Technol. , 18: 184-193.
11.
Liu, J.H. and Wang, A.Q. (2008). Study on Superabsorbent Composites XXI. Synthesis, Characterization and Swelling Behaviors of Chitosan-g-Poly(Acrylic Acid)/Organo-Rectorite Nanocomposite Superabsorbents, J. Appl. Polym. Sci., 110: 678-686.
12.
Su, X.F. , Zhang, G., Xu, K., Wang, J.H., Song, C.L. and Wang, P.X. (2008). The Effect of MMT/Modified MMT on the Structure and Performance of the Superabsorbent Composite, Polym . Bull., 60: 69-78.
13.
Zheng, Y.A. and Wang, A.Q. (2009). Study on Superabsorbent Composite. XX. Effects of Cation-Exchanged Montmorillonite on Swelling Properties of Superabsorbent Composite Containing Sodium Humate, Polym. Compos., 30: 1138-1145.
14.
Xie, Y.T. , Wang, A.Q. and Liu, G.Superabsorbent Composite XXII: Effects of Modified Sepiolite on Water Absorbency and Swelling Behavior of Chitosan-g-Poly (Acrylic Acid)/ Sepiolite Superabsorbent Composite, Polym. Compos., DOI 10.1002/pc.20770.
15.
Xu, J., Li, R.K.Y., Xu, Y., Li, L. and Meng, Y.Z. ( 2005). Preparation of Poly (Propylene Carbonate)/Organo-Vermiculite Nanocomposites via Direct Melt Intercalation, Eur. Polym. J., 41: 881-888.
16.
Fonseca, M.G. , Oliveira, M.M., Arakaki, L.N.H., Espinola, J.G.P. and Airoldi , C. (2005). Natural Vermiculite as an Exchanger Support for Heavy Cations in Aqueous Solution , J. Colloid Interf. Sci., 285: 50-55.
17.
Xie, Y.T. and Wang, A.Q. (2009). Study on Superabsorbent Composites XIX. Synthesis, Characterization and Performance of Chitosan-g-Poly (Acrylic Acid)/Vermiculite Superabsorbent Composites, J. Polym. Res., 16: 143-150.
18.
Lanthong, P. , Nuisin, R. and KiatKamjornwong , S. (2006). Graft Copolymerization, Characterization, and Degradation of Cassava Starch-g-Acrylamide/Itaconic Acid Superabsorbents, Carbohydr. Polym., 66: 229-245.
19.
Yoshimura, T., Uchikoshi, I., Yoshiura, Y. and Fujioka, R. (2005). Synthesis and Characterization of Novel Biodegradable Superabsorbent Hydrogels Based on Chitin and Succinic Anhydride, Carbohydr. Polym., 61: 322-326.
20.
Marandi, G.B. , Sharifnia, N. and Hosseinzadeh , H. (2006). Synthesis of an Alginate-Poly (Sodium Acrylate-Co-Acrylamide) Superabsorbent Hydrogel with Low Salt Sensitivity and High pH Sensitivity, J. Appl. Polym. Sci., 101: 2927-2937.
21.
Yoshimura, T., Sengoku, K. and Fujioka, R. (2005). Pectin-based Surperabsorbent Hydrogels Crosslinked by Some Chemicals: Synthesis and Characterization, Polym . Bull., 55: 123-129.
22.
Wang, W.B., Zheng, Y.A. and Wang, A.Q. ( 2008). Syntheses and Properties of the Superabsorbent Composites Based on Natural Guar Gum and Attapulgite, Polym. Adv. Technol. , 19: 1852-1859.
23.
Chen, Y. and Tan, H.M. ( 2006). Crosslinked Carboxymethylchitosan-g-Poly(Acrylic Acid) Copolymer as a Novel Superabsorbent Polymer, Carbohydr. Res. , 341: 887-896.
24.
Zhang, J.P., Chen, H. and Wang, A.Q. ( 2007). Study on Superabsorbent Composite. XV. Effects of Ion-exchanged Attapulgite on Water Absorbency of Superabsorbent Composites, Polym. Compos., 28: 208-213.
25.
Tomanec, R., Popov, S., Vučinič D. and Lazič P. ( 1997). Vermiculite from Kopaonik (Yugoslavia) Characterization and Processing, Physicochem. Prob. Miner. Process., 31: 247-254.
26.
Tang, Q.W., Lin, J.M., Wu, J.H., Xu, Y.W. and Zhang, C.J. ( 2007). Preparation and Water Absorbency of a Novel Poly (Acrylate-Co-Acrylamide)/Vermiculite Superabsorbent Composite, J. Appl. Polym. Sci., 104: 735-739.
27.
Zhang, J.P., Wang, Q. and Wang, A.Q. ( 2007). Synthesis and Characterization of Chitosan-g-Poly(Acrylic Acid)/Attapulgite Superabsorbent Composites, Carbohydr. Polym. , 68: 367-374.
28.
Wang, W.J., Zhang, J.P., Chen, H. and Wang, A.Q. ( 2006). Study on Superabsorbent Composite. VIII. Effects of Acid- and Heat-activated Attapulgite on Water Absorbency of Polyacrylamide/Attapulgite , J. Appl. Polym. Sci., 103: 2419-2424.
29.
Zhang, J.P. , Chen, H. and Wang, A.Q. (2006). Study on Superabsorbent Composite. IV. Effects of Organification Degree of Attapulgite on Swelling Behaviors of Polyacrylamide/Organo-Attapulgite Composites, Eur. Polym., 42: 101-108.
30.
Kiatkamjornwong, S., Mongkolsawat, K. and Sonsuk, M. (2002). Synthesis and Property Characterization of Cassava Starch Grafted Poly [Acrylamide-Co-(Maleic Acid)] Superabsorbent via γ-Irradiation, Polymer, 43: 3915-3924.
31.
Nisato, G., Munch, J.P. and Candau, S.J. ( 1999). Swelling, Structure, and Elasticity of Polyampholyte Hydrogels, Langmuir, 15: 4236-4244.
32.
Wang, W.B. and Wang, A.Q. ( 2009). Synthesis, Swelling Behaviors, and Slow-Release Characteristics of a Guar Gum-g-Poly (Sodium Acrylate)/Sodium Humate Superabsorbent, J. Appl. Polym. Sci., 112: 2102-2111.
33.
Kiatkamjornwong, S., Chomsaksakul, W. and Sonsuk, M. (2000). Radiation Modification of Water Absorption of Cassava Starch by Acrylic Acid/Acrylamide, Radiat. Phys. Chem., 59: 413-427.
34.
Omidian, H. , Hashemi, S.A., Sammes, P.G. and Meldrum, I. (1998). A Model for the Swelling of Superabsorbent Polymers, Polymer, 39: 6697-6704.
35.
Kabiri, K., Omidian, H., Hashemi, S.A. and Zohuriaan-Mehr, M.J. ( 2003). Synthesis of Fast-Swelling Superabsorbent Hydrogels: Effect of Crosslinker Type and Concentration on Porosity and Absorption Rate, Eur. Polym. J., 39: 1341-1348.
