CMC-g-PAA/APT/HA复合高吸水性树脂的制备与溶胀性能

以羧甲基纤维素(CMC)为基质,丙烯酸(AA)为单体,凹凸棒黏土(APT)和腐植酸(HA)为复合组分,采用水溶液聚合法制备了羧甲基纤维素接枝聚丙烯酸/凹凸棒黏土/腐植酸(CMC-g-PAA/APT/HA)环境友好复合高吸水性树脂,用红外光谱(FTIR)进行了结构表征。考查了APT和HA含量对树脂吸水倍率和吸水速率的影响,研究了树脂在不同pH溶液中的溶胀行为以及反复吸水性能。试验结果表明,APT和HA通过其表面的活性基团参与了接枝共聚反应,在体系中引入HA和APT能够显著提高复合高吸水性树脂的吸水能力。在HA含量为5%(质量分数),APT含量为30%(质量分数)时,树脂可达到最优吸蒸馏水倍率为582g/g。该复合高吸水性树脂在pH值在4～11范围内时具有较高的吸水性能,表现出优异的pH稳定性。经过5次反复溶胀后,该复合吸水树脂仍能达到424g/g的吸水倍率,较不含APT和HA样品提高了近44%。     

AC/XG-g-PAA复合高吸水树脂的制备及性能研究

利用溶液聚合法制备了AC/XG-g-PAA有机-无机复合高吸水性树脂。研究了丙烯酸用量、引发剂用量、丙烯酸中和度、凹凸棒黏土用量、交联剂用量和聚合反应温度等因素对合成复合高吸水性树脂性能的影响,利用傅立叶变换红外光谱仪(FTIR)、扫描电镜仪(SEM)、X射线衍射仪(XRD)和示差扫描量热仪(DSC)对产物进行表征。结果表明,丙烯酸分子与黄原胶发生接枝共聚,凹凸棒黏土与接枝共聚物发生了有机-无机复合,制备的AC/XG-g-PAA高吸水性树脂具有良好的吸水和抗盐性能,提高了高温保水性能,接枝率达137.2%,接枝效率达83.6%,最高吸水倍率达896g/g,吸盐水倍率达126.3g/g。     

AC/XG-g-PAA复合高吸水性树脂的制备及性能研究

利用溶液聚合法制备了AC/XG-g-PAA有机-无机复合高吸水性树脂。研究了丙烯酸用量、引发剂用量、丙烯酸中和度、凹凸棒黏土用量、交联剂用量和聚合反应温度等因素对合成复合高吸水性树脂性能的影响,利用傅立叶变换红外光谱仪(FTIR)、扫描电镜仪(SEM)、X射线衍射仪(XRD)和示差扫描量热仪(DSC)对产物进行表征。结果表明,丙烯酸分子与黄原胶发生接枝共聚,凹凸棒黏土与接枝共聚物发生了有机-无机复合,制备的AC/XG-g-PAA高吸水性树脂具有良好的吸水和抗盐性能,提高了高温保水性能,接枝率达137.2%,接枝效率达83.6%,最高吸水倍率达896g/g,吸盐水倍率达126.3g/g。     

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。     

LS-g-PAMPS/AA高吸水性树脂的微波合成及吸水性能

以木质素磺酸钠(LS-Na)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)、丙烯酸(AA)为原料,采用微波辐射法,通过接枝共聚合成LS-g-PAMPS/AA高吸水性树脂。探讨了微波功率、辐射时间对树脂吸水倍率的影响,研究了树脂在各种pH溶液中的溶胀行为,探讨了树脂的吸水速率、保水和反复吸水性能。结果表明,引入适量的LS-Na可以显著提高树脂的吸水速率、保水和反复吸水性能。树脂具有pH敏感性,在pH值4~12之间保持较高的吸水倍率,在pH值2与7的溶液里有良好的可逆行为。     

XG-g-PAA/OMMT有机-无机杂化复合高吸水性材料

利用溶液聚合法制备了黄原胶-g-聚丙烯酸/有机蒙脱土(XG-g-PAA/OMMT)有机-无机杂化复合高吸水性材料。当蒙脱土用量为丙烯酸质量的6%时,XG-g-PAA/OMMT的吸水倍率高达882 g/g,吸w(NaCl)=0.9%的水溶液倍率达到106.5 g/g。借助红外光谱仪、X射线衍射仪、扫描电镜、差示扫描量热仪和热重分析仪对合成产物进行了研究。结果表明,黄原胶分子与丙烯酸发生接枝共聚,蒙脱土的加入改变了XG-g-PAA的晶态结构,使复合高吸水性材料形成的网络空间增大,吸水抗盐性能和热稳定性能提高。通过研究复合高吸水性材料的吸水溶胀过程探讨其吸水动力学机理,表明XG-g-PAA/OMMT的吸水动力学扩散模型主要为non-Fickon扩散。     

瓜尔胶基高吸水性树脂的制备、溶胀行为与保水性能

以天然瓜尔胶（GG）和丙烯酸（AA）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（GG-g-PAA）高吸水性树脂。考察了MBA浓度对树脂溶胀动力学和溶胀能力的影响,研究了树脂在不同亲水有机溶剂/水混合溶液、不同阳离子盐（NaCl、CaCl₂和FeCl₃）和阴离子盐（KNO₃、K₂SO₄和K₃PO₄）溶液中在各浓度和离子强度下的溶胀行为,测定了高吸水性树脂在室温和高温下的保水性能。结果表明,该树脂对亲水有机溶剂较为敏感,吸水倍率随着亲水有机溶剂浓度的增加迅速减小;在各种盐溶液中的吸水倍率随着离子强度的增加而下降。     

微波辐射APT–g-PAMPS高吸水性树脂的制备及性能

以凹凸棒黏土(APT)和2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为原料,过硫酸钾(KPS)为引发剂,N,N'-亚甲基双丙烯酰胺(NMBA)为交联剂,采用微波辐射法接枝共聚合成了APT-g-PAMPS耐盐性复合高吸水性树脂,用FTIR和XRD对复合吸水性树脂的结构进行了表征。考察了微波功率和时间及APT用量对树脂吸水倍率的影响,测定了不同APT用量高吸水性树脂的吸水速率、保水性能及反复吸水性能。FTIR和XRD结果显示,APT和有机单体之间发生了接枝共聚反应,其反应仅在APT的表面进行,单体并没有插入到APT的层间。结果表明,微波功率为195 W,辐射时间为2.5 min,w(APT)=5%时,树脂在去离子水和生理盐水中的吸水倍率分别为987g/g和102 g/g。该复合高吸水性树脂具有较快的吸水速率、较强的保水性能和较好的反复吸水性能。在体系中引入适量APT能够显著提高复合吸水树脂的吸水能力和耐盐性能,同时能明显加快树脂的吸水速率和提高树脂的保水性能。     

P(AA/AM/APEG)/纳米二氧化硅复合高吸水树脂的合成及性能

以丙烯酸(AA)、丙烯酰胺(AM)、烯丙基聚氧乙烯醚(APEG)为单体,再引入纳米二氧化硅(nano-SiO_2),以过硫酸铵为引发剂,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P(AA/AM/APEG)/纳米二氧化硅有机/无机复合高吸水性树脂,考察了交联剂加量、引发剂加量、纳米二氧化硅加量对树脂吸水倍率的影响,并用红外光谱和扫描电镜对产物进行了表征。结果表明:合成最佳条件加入纳米二氧化硅能提高树脂的吸水性能,粒径在80~120目时,复合树脂吸水倍率达到1 865 g/g,P(AA/AM/APEG)树脂吸水倍率为1 681g/g;温度在20~60℃时,复合吸水树脂吸水倍率变化幅度不大;pH在6~8时,其吸水性能最好,吸水倍率为1 865~1 444 g/g;此外,复合树脂具有较好的保水性能,树脂常温下保存15 d,其保水率达到83.2%。红外光谱和扫描电镜分析表明,纳米二氧化硅成功接枝到聚合物上并形成海绵状结构。     

XG-g-PAA/OMMT有机-无机杂化复合高吸水性材料的研究

利用溶液聚合法制备了黄原胶-g-聚丙烯酸/有机蒙脱土(XG-g-PAA/OMMT) 有机-无机杂化复合高吸水性材料。当蒙脱土用量为丙烯酸质量的6%时,XG-g-PAA/OMMT的吸水倍率高达882g•g–1,吸0.9%NaCl溶液倍率达到106.5g•g–1。借助红外光谱、X-射线衍射仪、扫描电镜、差示扫描量热仪和热重分析仪对合成产物进行研究。结果表明：黄原胶分子与丙烯酸发生接枝共聚,蒙脱土的加入改变了XG-g-PAA的晶态结构,使复合高吸水性材料形成的网络空间增大,吸水抗盐性能和热稳定性能提高。通过研究复合高吸水性材料的吸水溶胀过程探讨其吸水动力学机理,表明XG-g-PAA/OMMT的吸水动力学扩散模型主要为non-Fickon扩散。     

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     

Superabsorbent composite XXII: Effects of modified sepiolite on water absorbency and swelling behavior of chitosan‐g‐poly(acrylic acid)/sepiolite superabsorbent composite

In this work, a series of chitosan‐g‐poly(acrylic acid)/sepiolite (CTS‐g‐PAA/ST) superabsorbent composites containing raw sepiolite, acid‐activated sepiolite, and cation‐exchanged sepiolite 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 raw sepiolite, acid‐activated sepiolite, and cation‐exchanged sepoilite on equilibrium water absorbency, swelling rate, and swelling behavior in different pH value solution of superabsorbent composites were systematically investigated. The results from FTIR spectra showed that chitosan and sepiolite participated in graft polymerization reaction with acrylic acid. The introduction of acid‐activated and cation‐exchanged sepiolite into chitosan‐g‐poly(acrylic acid) polymeric network could improve water absorbency and swelling rate compared with that of the raw sepiolite. All prepared samples have similar swelling behavior in different pH solutions and the equilibrium water absorbencies of samples keep roughly constant in the pH range from 4 to 12. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Preparation and Sand-Fixing Property of a Novel and Eco-friendly Organic-Inorganic Composite

A novel guar gum/poly(acrylic acid)/loess (GG-g-PAA/loess) organic-inorganic composite used as chemical sand-fixing agent (CSFA) is successfully prepared in aqueous solution by polymerization guar gum (GG), neutralized acrylic acid (AA) and loess. The correlations between the content of prepared composite and the sand-fixing properties are investigated. The results show that the CSFA can significantly improve the compressive strength of the sand fixation specimens. Meanwhile, the sand fixation specimens have good thermal, freeze-thaw and UV-radiation aging stabilities to withstand the changes in temperature and strong UV radiation. Besides, the specimens treated with sand-fixing agent shows excellent water retention capacity.     

Study on superabsorbent composite. XI. Effect of thermal treatment and acid activation of attapulgite on water absorbency of poly(acrylic acid)/attapulgite superabsorbent composite

The effect of acid activation and thermal treatment of attapulgite on water absorbency of superabsorbent composite were investigated. Under the same preparation conditions, superabsorbent composite prepared with natural attapulgite exhibited a water absorbency of 639 g/g and it merely kept 71% of its initial water absorbency after 5 times of swelling–deswelling–reswelling test. However, superabsorbent composites prepared with 2–10 M hydrochloric acid acidified attapulgite and 100–400°C thermal treated attapulgite respectively exhibited the water absorbency of 884–1,241 g/g and 701–1,515 g/g. Also, those superabsorbent composites can keep 87% and 85% of their initial water absorbency after 5 times of swelling–deswelling–reswelling test, respectively. These results showed that, compared with superabsorbent composite prepared with natural attapulgite, the comprehensive water‐absorbing properties of poly(acrylic acid)/ attapulgite superabsorbent composites were improved effectively by acid activation and thermal treatment of attapulgite. This improvement of water absorbencies and gel strength of superabsorbent composite may be due to synthetical factors such as changes in the crystalline structure and the specific surface area and improvement of the number and the activity of hydroxyl groups of attapulgite, which in turn influence the grafting efficiency of monomer, crosslinking density, and the structure of superabsorbent composite network. POLYM. COMPOS., 28:397–404, 2007. © 2007 Society of Plastics Engineers     

Synthesis,swelling behaviors,and slow‐release characteristics of a guar gum‐g‐poly(sodium acrylate)/sodium humate superabsorbent

Superabsorbents used in agricultural and ecological projects with low‐cost, slow‐release fertilizers and environmentally friendly characteristics have been extensively studied. The use of a natural polymer as the matrix and then further polymerization with some functional material has become the preferred method. In this work, with natural guar gum (GG), partially neutralized acrylic acid, and sodium humate (SH) as the raw materials, ammonium persulfate as the initiator, and N,N′‐methylenebisacrylamide (MBA) as the crosslinker, GG‐g‐poly(sodium acrylate) (PNaA)/SH superabsorbents were synthesized through a solution polymerization reaction and were characterized with Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The effects of the SH content and MBA concentration on the water absorbency were investigated. The results showed that the introduction of SH into the GG‐g‐PNaA system could improve the water absorbency, swelling rate, pH‐resistant property, and reswelling capability, and the superabsorbent containing 15 wt % SH had the highest water absorbency of 532 g/g of sample in distilled water and 62 g/g of sample in a 0.9 wt % NaCl solution. The slow release in water and water retention in sandy soil tests revealed that the superabsorbent could act as a fertilizer as well as an effective water‐saving material for agricultural applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Study on superabsorbent composites XIX. Synthesis, characterization and performance of chitosan-g-poly (acrylic acid)/vermiculite superabsorbent composites

A novel chitosan-g-poly (acrylic acid)/unexpanded vermiculite (CTS-g-PAA/UVMT) superabsorbent composite was prepared by graft polymerization among chitosan (CTS), acrylic acid (AA) and unexpanded vermiculite (UVMT) in aqueous solution. The effect of polymerization variables, including the content of crosslinker, initiator and UVMT, the weight ratio of AA to CTS, the reaction temperature, time and drying method, on water absorbency were studied. The swelling rate of the superabsorbent composite in distilled water was also investigated. The results from FTIR spectra showed that CTS and UVMT participated in graft polymerization reaction with AA. Introducing UVMT into the CTS-g-PAA polymeric network could form a loose and more porous structure by the SEM analysis, and the polymerization reaction is performed on the surface of UVMT micropowders from the results of XRD. The introduced UVMT enhanced the swelling rate and the water absorbency of CTS-g-PAA/UVMT superabsorbent composite.     

Swelling study of superabsorbent PAA‐co‐PAM/clay nanohydrogel

A series of superabsorbent composites were prepared from acrylic acid (AA), acrylamide (AM), and Cloisite® 30B by aqueous solution polymerization technique using ammonium peroxodisulfate (APS) as initiator. The interaction of the organically modified nanoclay with PAA‐co‐PAM copolymer was verified by FTIR, whereas the morphology of the composite was studied by Scanning Electron Microscopy (SEM). The water absorbency in deionized water and saline water of the synthesized nanohydrogels was measured by calculating their percentage swelling ratio. The effects of copolymerization, monomer ratio, clay content, and temperature on the water absorbency were studied. The results indicated a considerable increase in swelling ratio by proper monomer proportion and incorporation of optimum clay percentage into the copolymer matrix. It was found that the nanohydrogel acquired highest water absorbency with 2% clay loading. The reswelling ability and water retention capacity of the PAA‐co‐PAM hydrogel and PAA‐co‐PAM/clay nanohydrogel were also measured. The water absorbency was found to increase after each reswelling for which it may be useful as recyclable superabsorbent material. The results of water retention capacity of the nanohydrogel were also encouraging and find application in agriculture, especially in drought‐prone areas. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and swelling characteristics of a pH‐responsive guar gum‐g‐poly(sodium acrylate)/medicinal stone superabsorbent composite

A series of pH‐responsive superabsorbent composites were synthesized by the free‐radical grafting copolymerization of natural guar gum (GG), partially neutralized acrylic acid (NaA), and medicinal stone (MS) using ammonium persulfate (APS) as the initiator and N,N′‐methylene‐bis‐acrylamide (MBA) as the crosslinker. The structure, surface morphologies, and thermal stability of the developed composites were characterized by FTIR spectra, SEM, and TGA techniques, respectively. The effects of various saline, surfactant, and dye solutions on swelling properties were investigated, and the pH‐responsivity was also evaluated. Results indicated that NaA had been grafted onto GG macromolecular chains and MS participated in the polymerization reaction. The incorporation of MS obviously improved the surface structure, thermal stability, water absorption capacity, and rate. Multivalent saline, cationic surfactant, and dye showed more remarkable effect on the water absorption than did monovalent or anionic ones. The composites showed excellent responsive properties and reversible On–Off switching characteristics in various pH buffer solutions, which provided great possibility to extend the application domain of the superabsorbent composites. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers