Studies on poly(acrylic acid)/attapulgite superabsorbent composite. I. Synthesis and characterization

A novel poly(acrylic acid)/attapulgite superabsorbent composite was synthesized by graft copolymerization reaction of acrylic acid (AA) on attapulgite micropowder using N,N′‐methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator in aqueous solution. The effects on water absorbency of such factors as reaction temperature, initial monomer concentration, degree of neutralization of AA, amount of crosslinker, initiator, and attapulgite were investigated. These crosslinked superabsorbent composites were characterized by thermogravimetetric analysis and scanning electron microscopy. The graft copolymerization reaction of AA on attapulgite micropowder was characterized by FTIR. The water absorbencies for these superabsorbent composites in water and saline solutions were investigated and water‐retention tests were carried out. Results obtained from this study show that the water absorbency of the superabsorbent composite synthesized under optimal synthesis conditions with an attapulgite content of 10% exhibited an absorption of 1017 g H₂O/g sample and 77 g H₂O/g sample in distilled water and in 0.9 wt % NaCl solution, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1596–1603, 2004     

Synthesis of poly(acrylic acid)/sodium humate superabsorbent composite for agricultural use

A novel poly (acrylic acid)/sodium humate superabsorbent composite was synthesized by graft copolymerization reaction of acrylic acid (AA) on sodium humate micropowder using N,N′‐methylenebisacrylamide (MBA) as a crosslinker and potassium peroxydisulfate (KPS) as an initiator in aqueous solution. The effects on water absorbency of factors such as reaction temperature, initial monomer concentration, and degree of neutralization of AA, amount of crosslinker, initiator, and sodium humate were investigated. The superabsorbent composite was characterized by scanning electron microscopy, and the graft copolymerization reaction of AA on sodium humate micropowder was characterized by IR spectroscopy. Results obtained from this study show that the water absorbency of the superabsorbent composite synthesized under optimal conditions for synthesis with a sodium humate content of 5.3% exhibited absorption of 684 g H₂O/g sample in distilled water. Water‐retention in soil is enhanced by the use of the superabsorbent composite. The effect of superabsorbent composite on the growth of corn is reported. The superabsorbent composite may be of use as water management materials for agriculture purposes in desert and drought‐prone areas. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5137–5143, 2006     

Synthesis and properties of carboxymethyl cellulose‐graft‐poly(acrylic acid‐co‐acrylamide) as a novel cellulose‐based superabsorbent

A new cellulose‐based superabsorbent polymer, carboxymethyl cellulose‐graft‐poly(acrylic acid‐co‐acrylamide), was prepared by the free‐radical grafting solution polymerization of acrylic acid (AA) and acrylamide (AM) monomers onto carboxymethyl cellulose (CMC) in the presence of N,N′‐methylenebisacrylamide as a crosslinker with a redox couple of potassium persulfate and sodium metabisulfite as an initiator. The influences of reaction variables such as the initiator content, crosslinker content, bath temperature, molar ratio of AA to AM, and weight ratio of the monomers to CMC on the water absorbency of the carboxymethylcellulose‐graft‐poly(acrylic acid‐co‐acrylamide) copolymer were investigated. The copolymer's structures were characterized with Fourier transform infrared spectroscopy. The optimum reaction conditions were obtained as follows: the bath temperature was 50°C; the molar ratio of AA to AM was 3 : 1; the mass ratio of the monomers to CMC was 4 : 1; and the weight percentages of the crosslinker and initiator with respect to the monomers were 0.75 and 1%, respectively. The maximum water absorbency of the optimized product was 920 g/g for distilled water and 85 g/g for a 0.9 wt % aqueous NaCl solution. In addition, the superabsorbent possessed good water retention and salt resistance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1382–1388, 2007     

Synthesis,characterization and swelling behaviors of hydroxyethyl cellulose‐g‐poly(acrylic acid)/attapulgite superabsorbent composite

In this work, a series of novel hydroxyethyl cellulose‐ g‐poly(acrylic acid)/attapulgite (HEC‐g‐PAA/APT) superabsorbent composites were prepared through the graft polymerization of hydroxyethyl cellulose (HEC), partially neutralized acrylic acid (AA), and attapulgite (APT) in aqueous solution, and the composites were characterized by means of Fourier‐transform spectroscopy, scanning electron microscopy, and transmission electronmicroscopy. The effects of polymerization variables including concentrations of the initiator and crosslinker and APT content on water absorbency were studied, and the swelling properties in various pH solutions as well as the swelling kinetics in various saline solutions were also systematically evaluated. Results showed that the introduction of 5 wt% APT into HEC‐g‐PAA polymeric network could improve both water absorbency and water absorption rate of the superabsorbent composites. In addition, the superabsorbent composites retained high water absorbency over a wide pH range of 4–10, and the swelling kinetics of the superabsorbent composites in CaCl₂ and FeCl₃ solutions exhibited a remarkable overshooting phenomenon. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

GG-g-PAA/LOESS复合高吸水性树脂的制备与性能

以瓜尔胶(GG)、丙烯酸(AA)和黄土(LOESS)为原料,过硫酸铵(APS)为引发剂,N,N'-亚甲基双丙烯酰胺(MBA)为交联剂,采用水溶液聚合法制备了瓜尔胶接枝聚丙烯酸/黄土(GG-g-PAA/LOESS)复合高吸水性树脂。采用FTIR和SEM对其结构进行了表征,研究了LOESS的添加量对复合高吸水性树脂的溶胀能力和溶胀动力学的影响,考察了复合高吸水性树脂的保水性能、反复溶胀性以及在不同pH溶液中的吸水性能。结果表明,瓜尔胶、丙烯酸和LOESS发生了接枝共聚,体系中引入LOESS能够显著提高复合高吸水性树脂的吸水性能。当LOESS的质量分数为2%时,该树脂最高吸水倍率可达602 g/g,室温下6 d后,其保水率仍达28%,5次反复溶胀,吸水倍率仍能保持初始时的49%。此外,该复合高吸水性树脂还表现出优异的pH稳定性。     

Synthesis and properties of a poly(acrylic acid)/montmorillonite superabsorbent nanocomposite

A novel superabsorbent nanocomposite was synthesized through the intercalation polymerization of partially neutralized acrylic acid and a sodium‐type montmorillonite powder with N,N′‐methylenebisacrylamide as a crosslinker and ammonium persulfate and sodium sulfite as a type of mixed redox initiator. The effects of such factors as the amounts of the sodium‐type montmorillonite, crosslinker, and initiator and neutralization degree on the water absorbency of the nanocomposite were investigated. The structure and micrographs of the superabsorbent were characterized with Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy. The results showed that the acrylic acid monomer was successfully intercalated into the montmorillonite layers and banded together with them. The montmorillonite layers were exfoliated and basically dispersed in the composite on a nanoscale after the polymerization. The water absorbency of the nanocomposite was much higher than that of pure poly(acrylic acid). The optimum absorbency of the nanocomposite in distilled water and saline water (NaCl concentration = 0.9%) was 1201 and 83 g/g, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5725–5730, 2006     

Preparation of starch‐graft‐poly(acrylamide)/attapulgite superabsorbent composite

A novel starch‐graft‐poly(acrylamide)/attapulgite superabsorbent composite was synthesized by graft copolymerization reaction of starch, acrylamide (AM), and attapulgite micropowder using N.N‐methylene‐bisacrylamide (MBA) as a crosslinker and ammonium persulphate (APS) as an initiator in aqueous solution, followed by hydrolysis with sodium hydroxide. The effects on water absorbency, such as amount of crosslinker, initiator, attapulgite, weight ratio of acrylamide to starch in the feed, gelatinization conditions of starch and molar ratio of NaOH to acrylamide, and so forth, were investigated. These superabsorbent composites were characterized by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The water absorbencies for these superabsorbent composites in water and saline solution were investigated, and water retention tests were carried out. Results obtained from this study showed that the water absorbency of superabsorbent composite synthesized under optimal synthesis conditions with an attapulgite content of 10% exhibit absorption of 1317 g H₂O/g sample and 68 g H₂O/g sample in distilled water and in 0.9 wt % NaCl solution, respectively. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1351–1357, 2005     

Study on superabsorbent composites. XVIII. Preparation,characterization, and property evaluation of poly(acrylic acid‐co‐acrylamide)/organomontmorillonite/sodium humate superabsorbent composites

A series of novel multifunctional poly (acrylic acid‐co‐acrylamide) (PAA‐AM)/organomontmorillonite (O‐MMT)/sodium humate (SH) superabsorbent composites were synthesized by the graft copolymerization reaction of partially neutralized acrylic acid and acrylamide on O‐MMT micropowder and SH with N,N′‐methylene bisacrylamide as a crosslinker and ammonium persulfate as an initiator in an aqueous solution. The superabsorbent composites were characterized by means of Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, and thermogravimetric analysis. The effect of the relative weight ratio of SH to O‐MMT on the water absorbency was studied, and the results indicated that the best water absorbency of 591 g/g in distilled water was obtained when an O‐MMT content of 20 wt % and an SH content of 30 wt % were incorporated. The superabsorbent composite possessed a good capacity for water retention; even after 30 days, 24.4 wt % of water could still be saved by the sand soil containing 1.0 wt % superabsorbent composite. The results from this study show that the water absorbency of a superabsorbent composite is improved by the simultaneous introduction of O‐MMT and SH into a PAA‐AM network in comparison with the incorporation of only O‐MMT or SH. Also, in comparison with PAA‐AM/MMT/SH, an appropriate amount of O‐MMT can benefit the developed composites with respect to their water absorbency, salt resistance, and capacity for water retention in sand soil. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Waste polystyrene foam‐graft‐acrylic acid/montmorillonite superabsorbent nanocomposite

A novel superabsorbent nanocomposite based on partially neutralized acrylic acid, waste polystyrene foam, and sodium type montmorillonite (Na‐MMT) powder was synthesized through emulsion polymerization using N, N′‐methylenebisacrylamide as a crosslinker, 2,2′‐azo‐bisiso‐butyronitrile, ammonium persulfate, and sodium sulfite as mixed redox initiators. The effects of such factors as amount of Na‐MMT, crosslinker, initiator, and neutralization degree on water absorbency of the superabsorbent were investigated. The composites were characterized by Fourier transform infrared spectroscope, X‐ray diffraction, thermo gravimetric analysis, and scanning electron microscope. The results show that acrylic acid monomer successfully grafted onto the polystyrene chain, the layers of Na‐MMT were exfoliated and dispersed in the composite at nano size after copolymerization. The introduction of waste polystyrene foam in the composite increased the water absorbency rate. The addition of Na‐MMT not only enhanced the thermal stability of the composites but also increased its water absorbency, and the optimal water absorbencies of distilled water and saline water (w_NaCl = 0.9%) of the nanocomposites were more than 1180 g H₂O/g and 72.6 g H₂O/g, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2341–2349, 2007     

Synthesis of AA‐based superabsorbent interpenetrated with sodium PVA sulfate

An interpenetrating network of acrylic acid (AA)‐based superabsorbents and sodium PVA sulfate (SPS) were prepared by copolymerizing AA and N,N′‐methylene bisacrylamide as a crosslinking monomer in a solution of SPS with KPS, a radical initiator. The SPS was prepared through the sulfation of the hydroxyl groups of PVA with DMF‐SO₃ complex in DMSO. The AA‐based superabsorbent interpenetrated with SPS (SA‐IP‐SPS) showed superior properties such as higher water and saline absorbency, absorbency under load (AUL), and water retention value (WRV) compared with AA‐based superabsorbent due to the interpenetrated SPS. The maximum water and saline absorbency of SA‐IP‐SPS was 1753 and 125.6 g/g, respectively. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2525–2532, 2000     

Utilization of plant ash for the fabrication of novel superabsorbent composites with potassium‐release characteristics

Design and synthesis of the agricultural and ecological superabsorbent materials with cost‐efficient and fertilizer‐release characteristics has recently attracted considerable interests. In this work, the novel poly(sodium‐potassium acrylate‐co‐acrylamide)/plant ash (PNa‐KA‐co‐AM/PA) superabsorbent composites with potassium‐release characteristics were prepared using partially neutralized acrylic acid (Na‐KA), acrylamide (AM), and plant ash (PA) as raw materials, ammonium persulfate (APS) as the initiator, and N,N′‐methylenebisacrylamide (MBA) as the crosslinker. The structure, morphologies, and thermal stability of the composites were characterized by Fourier transform infrared spectrophotometer, scanning electron microscopy, and TGA techniques, respectively. The effects of MBA concentration and PA content on water absorbency were studied, and the swelling properties of the composites in saline solutions and various pHs solution as well as their potassium‐release capabilities were also evaluated. Results indicate that the composites exhibit better thermal stability, salt‐resistant performance, pH‐stability, and potassium‐release properties, and can act as a fertilizer and an effective water‐saving material for agricultural and ecological application. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and properties of a salt‐resistant superabsorbent polymer

Crosslinked sodium polyacrylate was prepared by solution polymerization with N,N‐methylene‐bisacrylamide (bisAM) as crosslinking agent; it was subsequently surface‐crosslinked by ethylene glycol diglycidyl ether (EGDE) and then was modified with inorganic salt to obtain a superabsorbent with water absorbency in 0.9 wt % NaCl aqueous solution at atmosphere and applied pressure (P ≈ 2 × 10³ Pa) of 55 and 20 g.g^?1, respectively. Moreover, it also had excellent hydrogel strength. The effects of reaction temperature, reaction time, neutralization degree (ND) of acrylic acid, amount of initiator, crosslinking agent, and surface‐crosslinking agent, mass ratio of inorganic salt to initial superabsorbent, molar ratio of sodium aluminate (NaAlO₂) to potassium dihydrogen hyphosphate (KH₂PO₄) on water absorbency (WA) in 0.9 wt % NaCl aqueous, and the hydrogel modulus were investigated and optimized. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2532–2541, 2004     

凹土基有机-无机复合高吸水性材料的制备及性能研究

应用水溶液聚合法,以丙烯酰胺和未纯化凹凸棒原土为原料制备了丙烯酰胺/凹凸棒土复合吸水性材料,考察了凹凸棒原土含量、交联剂含量和引发剂含量对复合吸水材料吸水性能的影响,并对制备条件进行了优化。结果表明当凹凸棒原土质量分数为10%,交联剂质量分数为0.06%,引发剂质量分数为0.4%时,复合吸水材料在蒸馏水中的吸水倍率最高,达到了719 g/g。     

Preparation of acrylic acid and AMPS cointercalated layered double hydroxide and its application for superabsorbent

This article reports the cointercalation of acrylic acid (AA) and 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) in the interlayer region of Mg₂Al layered double hydroxide (LDH) and the application of this inorganic–organic composite material in the field of water superabsorbent. The monomers of AA and AMPS were cointercalated into galleries of Mg₂Al−LDH (denoted as AA−AMPS/LDH) with various molar ratios by ion‐exchange method, which was confirmed by powder X‐ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), and elemental analysis. The polymer‐based superabsorbent was prepared through in situ free‐radical aqueous copolymerization of AA and AMPS, with AA−AMPS/LDH as additive, N,N′‐methylenebisacrylamide (NMBA) as crosslinker and potassium persulfate (KPS) as initiator. The composition of this poly(AA‐co‐AMPS)/LDH was demonstrated as a good water superabsorbent. The LDH content, water absorbency, thermal stability, and swelling rate of this superabsorbent were also investigated in detail. Results showed that the incorporation of a 5 wt % AA−AMPS/LDH into polymer matrix increased its water absorbency significantly by 27.7% (in water) and by 51.5% (in 0.9 wt % NaCl solution). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

凹凸棒黏土纯度对复合高吸水性树脂吸水性能的影响

将凹凸棒黏土分级处理后,以不同纯度的凹凸棒黏土为无机组分,过硫酸铵为引发剂,N,N'-亚甲基双丙烯酰胺为交联剂,制备了羧甲基纤维素接枝丙烯酸/凹凸棒黏土复合高吸水性树脂,考察了复合高吸水性树脂的吸水倍率、吸水速率和在不同pH介质中的溶胀性能。红外光谱表明,丙烯酸已接枝到羧甲基纤维素的骨架上,凹凸棒黏土参与了聚合反应。扫描电镜观察表明,凹凸棒黏土在高吸水性树脂中有良好的分散性能,改善了基体表面的多孔结构。研究表明,在相同添加量下,凹凸棒黏土中含有更多的Ca2+和Mg2+离子,有助于改善复合高吸水性树脂的综合性能。     

Preparation and slow‐release property of a poly(acrylic acid)/attapulgite/sodium humate superabsorbent composite

A novel poly(acrylic acid)/attapulgite (APT)/sodium humate (SH) superabsorbent composite was synthesized through the graft copolymerization reaction of acrylic acid on APT micropowder and SH with N,N′‐methylene bisacrylamide as a crosslinker and ammonium persulfate as an initiator in an aqueous solution. Various effects on the water absorbency, including the amounts of the crosslinker, initiator, APT, and SH, were investigated. The superabsorbent composite was characterized with Fourier transform infrared spectroscopy and scanning electron microscopy. The superabsorbent composite synthesized under optimal synthesis conditions with an APT concentration of 20% and an SH concentration of 20% exhibited absorption of 583 g of H₂O/g of sample and 63 g of H₂O/g of sample in distilled water and in a 0.9 wt % NaCl solution, respectively. The slow‐release property of SH from the superabsorbent composite into water was measured, and a test of the water retention of the superabsorbent composite in soil was also carried out experimentally with and without the superabsorbent composite. The results showed that the superabsorbent composite had not only good water retention but also an additional slow‐release property of SH. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 37–45, 2007     

Utilization of starch and montmorrilonite for the preparation of superabsorbent nanocomposite

Starch and montmorrilonite (MMT) were used as raw materials for synthesizing starch‐graft‐poly[acrylamide (AM)–acrylic acid (AA)]/MMT superabsorbent nanocomposite by graft and intercalation copolymerization reaction of starch, AM, and AA in the presence of organic MMT micropowder in aqueous solution. Major factors affecting water absorbency such as weight ratio of monomers to starch, weight ratio of AM to AA, neutralization degree of AA, amount of crosslinker, initiator, and MMT were investigated. The superabsorbent nanocomposite synthesized under optimal synthesis conditions exhibits absorption of 1120 g H₂O/g sample and 128 g H₂O/g sample in deionized water and in 0.9 wt % NaCl solution, respectively. IR spectra showed that the graft copolymerization between  OH groups on MMT and monomers took place during the reaction, and that crystal interlayer was pulled open in the superabsorbent nanocomposite. X‐ray diffraction analysis showed that the crystal interlayer of MMT was pulled open to 2.73 nm, and thus formed nanometer exfoliation composite material. Thermogravimetric analysis showed that starch‐graft‐poly (AM–AA) superabsorbent nanocomposite (8 wt % MMT) has good thermal stability. This superabsorbent nanocomposite with excellent water absorbency and water retention, being biodegradable in nature, economical and environment friendly, could be especially useful in industry, agricultural, and horticultural applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Study on superabsorbent composite. XV. Effects of ion‐exchanged attapulgite on water absorbency of superabsorbent composites

A series of superabsorbent composite, polyacrylamide/attapulgite, from acrylamide (AM) and ion‐exchanged attapulgite (APT) was prepared by aqueous polymerization, using N,N′‐methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator. The effects of ion‐exchanged APT on water absorbency of superabsorbent composites in distilled water and in 0.9 wt% NaCl solution were studied. The result indicates that higher cation‐exchange capacity (CEC) and lower specific surface area (SSA) of APT treated with various anions are of benefit for improving water absorbency in distilled water. The effects of AlCl₃ solution concentration and Al³⁺‐exchanged APT content on water absorbency of the composite were also investigated. The concentration of AlCl₃ solution has a great influence on water absorbency of the superabsorbent composite. Al³⁺‐exchange of APT could also enhance reswelling ability of the corresponding composite, which indicates that Al³⁺‐exchange of APT could improve gel strength and gives a direct evidence for its acting as an inorganic assistant crosslinker in the polymeric network. POLYM. COMPOS., 28:208–213, 2007. © 2007 Society of Plastics Engineers     

耐盐型丙烯酸-丙烯酰胺接枝共聚高吸水树脂的合成及其性能研究

采用溶液聚合法,以丙烯酸(AA)和丙烯酰胺(AM)为单体,N,N＇-亚甲基双丙烯酰胺(NMBA)为交联剂,过硫酸钾(KPS)为引发剂.合成出丙烯酸-丙烯酰胺接枝共聚高吸水树脂.探讨了单体比[m(丙烯酸):m(丙烯酰胺)]、交联剂和引发荆用量、单体中和度及聚合温度对树脂吸水率的影响.IR光谱表明,丙烯酸和丙烯酰胺发生了接...     

GG-g-PAA／SH高吸水性树脂的制备与缓释性能研究

以天然瓜尔胶（GG）、丙烯酸（AA）和腐植酸钠（SH）为原料,过硫酸铵为引发剂,N,N’-亚甲基双丙烯酰胺为交联剂,采用水溶液聚合法制备了环境友好的多功能瓜尔胶接枝聚丙烯酸／腐植酸钠（GG-g—PAA／SH）高吸水性树脂。考察了腐植酸钠含量对树脂吸水性能的影响,评价了树脂在沙土中的实际保水性能、反复溶胀性能和腐植酸钠肥料缓释性能。结果表明,在体系中引入廉价的腐植酸钠,不但降低生产成本,还能提高树脂的吸水能力,当腐植酸钠含量为15wt％时,高吸水性树脂吸蒸馏水和生理盐水的倍率分别为532g／g和62g／g。在沙土中加入高吸水性树脂能显著提高其保水性能,30d后仍能保持13％的水分。此外,GG-g-PAA／SH高吸水性树脂还具有较优的反复溶胀性能和腐植酸钠肥料缓释功能,可用作兼具吸水、保水和缓释性能的新型节水材料。