聚丙烯酰胺/凹凸棒土(Attapulgite)纳米复合高吸水性树脂的制备与性能

高吸水性树脂是一种新型功能高分子材料,由于其优越的吸水保水性能,已在农林园艺和生理卫生用品等领域得到了应用,但它仍然存在抗盐性能差、吸水后凝胶强度低等不足．近年来,有机．无机复合高吸水性树脂因具有较高的吸水性能和低廉的生产成本而受到了广泛的关注,使用的无机粘土主要有高岭土、蒙脱土和凹凸棒土等．粘土具有活性基团和键合点,加入到高吸水性树脂三维网络中可以改善树脂的网络结构,提高其综合性能．凹凸棒土是一种含水富镁铝的层链状硅酸盐,相对于其它粘土,它具有很好的抗盐、吸附和胶体性能。     

高吸水性枝脂研究进展

介绍了高吸水性树脂的结构,性能及其表征,结合经典理论与最新研究从热力学和动力学角度阐述其吸水机理,着重分析合成条件,组份和方法对高吸水性树脂性能的影响机制,简略地介绍了高吸水性树脂三十年来的发展及广阔的应用领域,并预测其研究与开发前景。     

高吸水性树脂的合成和应用

本文综述了近年来高吸水性树脂的研究进展,主要包括3个方面:(1)高吸水性树脂的制备;(2)高吸水性树脂的结构及性能表征;(3)高吸水性树脂的应用开发。     

高吸水性树脂研究进展

介绍了高吸水性树脂的结构、性能及其表征,结合经典理论与最新研究从热力学和动力学角度阐述其吸水机理,着重分析合成条件,组份和方法对高吸水性树脂性能的影响机制,简略地介绍了高吸水性树脂三十年来的发展及广阔的应用领域,并预测其研究与开发前景     

高吸水性树脂

高吸水性树脂,可以吸收其本身重量的几百倍水。将水溶性高分子如羧甲基纤维素、聚丙烯酸钠盐或聚乙烯醇进行轻微的交联可以得到。由于其高吸水性、在压力下的高保水性和高增稠性,被广泛应用于纸尿布、生理巾、土壤保水剂、工业脱水剂、增稠剂等。     

高吸水性树脂

综述了国内高吸水性树脂的研究进展,其中包括高吸水性树脂的制备方法、类型、影响其吸水性能的因素以及功能与应用。     

高吸水性树脂的合成与应用

综述了高吸水性树脂的研究、发展状况。并指出了高吸水性树脂研究中存在的问题。     

腐植酸高吸水性树脂研究进展

腐植酸（HA）是土壤腐殖质的主要成分,含有多种功能基团。随着HA基础和应用研究的不断深入,将具有反应活性和生物活性的HA引入到高吸水性树脂中,既能发挥HA改良土壤、增效化肥、刺激生长、增强抗逆和改善品质的功效,又可改善高吸水性树脂的吸水和耐盐性能,同时大幅度降低高吸水性树脂的制备成本。本文综述了近年来HA高吸水性树脂的...     

高吸水性树脂

用热力学理论和相转变理论阐明了高吸水性树脂的吸水机理。解释了高分子链上的电荷密度、外界溶液离子强度以及交联度对吸水倍数的影响，并指出了影响吸水速率的因素。介绍了淀粉类、纤维素类、共聚合类、复合类以及可生物降解类高吸水性树脂近30年来的研究状况以及存在的问题，简要介绍了高吸水性树脂的应用。     

高吸水性树脂溶胀热力学及吸水机理

分析了高吸水性树脂吸水的热力学本质，探讨了Flory公式的意义，通过简化的Flory公式得到吸水率与外部溶液离子强度的简单关系。同时，对高吸水性树脂在与水的相互作用以及溶胀过程进行了探讨，并以此为基础解释了一些吸水、保水现象。     

Study on superabsorbent composite. IV. Effects of organification degree of attapulgite on swelling behaviors of polyacrylamide/organo-attapulgite composites

A novel kind of superabsorbent composite, polyacrylamide/organo-attapulgite, from acrylamide (AM) and attapulgite (APT) was prepared by aqueous polymerization, using N,N′-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator. APT was organified with five different degree of hexadecyltrimethyl ammonium bromide (HDTMABr), and the organification degree of APT was proved by FTIR, TGA and XRD. The effects of organification degree of APT on water absorbency and swelling rate of the superabsorbent composite in distilled water and in various saline solutions were investigated in this study. The effect of organification degree on reswelling ability of the superabsorbent composites was also investigated. The results indicate that the organification degree of APT had remarkable influence on swelling behaviors of the superabsorbent composites. The superabsorbent composite acquired its highest water absorbency when the organification degree of APT is 8.02 wt.%.     

Synthesis and properties of clay-based superabsorbent composite

A novel superabsorbent composites based on acrylic acid, acrylamide, and inorganic clay mineral-attapulgite were synthesized through a solution polymerization to improve water and saline absorbencies. The superabsorbent composite was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The effects of saline solutions, amount of initiator, crosslinker and attapulgite on the water absorbency of superabsorbent composites were investigated. The water retention test of superabsorbent composites were also carried out. The superabsorbent composite exhibited improved water and saline absorbencies compared with that of crosslinked poly(acrylic acid-co-acrylamide) superabsorbent polymer. The water absorbency of the superabsorbent composite synthesized under optimal synthesis conditions with an attapulgite content of 10% reaches more than 1400 g H₂O/g and 110 g H₂O/g in distilled water and 0.9% NaCl solution, respectively.     

Syntheses and properties of superabsorbent composites based on natural guar gum and attapulgite

Utilization of raw materials available in nature and their application to derive other useful products without any adverse impact on the environment has long been a desired goal. In this work, guar gum (GG) and attapulgite (APT) clay were used as raw materials for preparing guar gum‐g‐poly(acrylic acid)/attapulgite (GG‐g‐PAA/APT) superabsorbent composites through the graft copolymerization of GG, partially neutralized acrylic acid (AA) and APT in aqueous solution. The effects of reaction conditions such as concentrations of the initiator and crosslinker, APT content, etc. on water absorbency were investigated. The composite prepared under optimal conditions gave the best absorption of 529 g/g sample in distilled water and 61 g/g sample in 0.9 wt% NaCl solution. Swelling behaviors revealed that the superabsorbent composites retained a high water absorbency over a wide pH range of 4–11, and the developed composites also exhibited improved reswelling and water‐retention capabilities. The superabsorbent composites can be utilized as eco‐friendly water‐manageable materials for agricultural and horticultural applications. Copyright © 2008 John Wiley & Sons, Ltd.     

Adsorption study for removal of Congo red anionic dye using organo-attapulgite

The organo-attapulgite was prepared using hexadecyltrimethylammonium bromide (HTMAB) with equation equivalent ratio of HTMAB to CEC of attapulgite added and then used as adsorbent for the removal of Congo red (CR) anionic dye from aqueous solution. Adsorbent characterizations were investigated using infrared spectroscopy and X-ray diffraction. The effects of contact time, temperature, pH and initial dye concentration on organo-attapulgite adsorption for CR were investigated. The results show that the amount adsorbed of CR on the organo-attapulgite increase with increasing dye concentration, temperature, and by decreasing pH. The adsorption kinetics was studied with the pseudo-first-order, pseudo-second-order and intraparticle diffusion models, and the rate constants were evaluated. It was found that the adsorption mechanisms in the dye/organo-attapulgite system follow pseudo-second-order kinetics with a significant contribution of film diffusion. Equilibrium data fitted perfectly with Langmuir isotherm model compared to Freundlich isotherm model, and the maximum adsorption capacity was 189.39 mg g⁻¹ for the adsorbent. Kinetic and desorption studies both suggest that chemisorption should be the major mode of CR removal by the organo-attapulgite. The results indicate that HTMAB-modified attapulgite could be employed as low-cost material for the removal of Congo red anionic dye from wastewater.     

ABS/clay nanocomposites obtained by a solution technique: Influence of clay organic modifiers

Acrylonitrile-butadiene-styrene (ABS) polymer/clay nanocomposites were produced using an intercalation-adsorption technique from polymer in solution: polymer/clay suspensions were subjected to ultrasonic processing to increase the effectiveness of mixing. Several kinds of organically modified layered silicates (OMLS) were used to understand the influence of the surfactant nature on the intercalation-exfoliation mechanism. We show that only imidazolium-treated montmorillonite (DMHDIM-MMT) is stable at the processing temperature of 200 °C, used for hot-pressing, whereas alkyl-ammonium modified clays show significant degradation.The morphology of ABS based polymer nanocomposites prepared in this work was characterized by means of wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). Dynamic-mechanical analysis (DMA) was used to determine the storage modulus and damping coefficient as a function of temperature, and to investigate the correlations between mechanical properties and morphology of the nanocomposites. The thermal stability was assessed by means of thermogravimetric analysis (TGA). DMA and TGA show that the nanocomposites based on imidazolium-modified clay out-perform the nanocomposites based on quaternary-ammonium-modified clays in terms of mechanical properties and thermal stability.     

改性凹凸棒的制备及对砷离子的吸附研究

针对日益严重的砷离子污染问题，本文采用灵敏简便的原子荧光分析法，探究了凹凸棒石粘土吸附剂对砷离子的吸附性能，测定了pH、吸附时间、砷离子的初始浓度等因素对凹凸棒石粘土负载铁氧化物对砷离子吸附能力的影响，并通过SEM、EDX、FTIR对所制得的吸附剂进行了表征研究，同时进行了吸附动力学和吸附等温模型的分析。研究结果表明，改性后的凹凸棒对砷离子的吸附性能有了显著提升，在较低浓度时吸附效率可达98%，该吸附符合Langmuir等温吸附模型和准二级动力学方程。     

Novel polycarbonate-based polyurethane elastomers: Composition–property relationship

Novel all-aliphatic polycarbonate-based polyurethane (PC-PU) elastomers, as well as PC-PU nanocomposites filled with organic-modified clays were synthesized, characterized and studied. It was found that they have very attractive mechanical properties (e.g., elongation at break between 600% and 800%). The prepared PC-PUs possess a distinctly segmented structure, which is the key prerequisite for their behavior as strong physical rubbery networks. All synthesized materials melt at elevated temperatures (between 110 and 200 °C) and hence can be processed like normal thermoplastics. The dispersion of the clay nanofiller was achieved by its one day swelling in the alcohol and a brief successive stirring. This procedure is very successful and leads to a partial exfoliation of the clay (documented by X-ray diffraction and TEM). The best nanocomposites with very good tensile properties, particularly with significantly increased moduli were obtained using the bentonite nanofiller. The study shows that the nanofiller interacts strongly with the hard domains and influences their melting temperature (DMTA and DSC), but it does not affect the glass transition temperature of soft domains. While Cloisite 15A was found to interact preferentially with the hard domains, the organic modified bentonite shows a strong interaction with both soft and hard segments, behaving as a blending agent. Hard domains in neat matrices, formed by hydrogen bonding of hard segments, were practically invisible by X-ray or TEM, but were successfully detected by AFM. Besides excellent mechanical properties, the prepared elastomers and their nanocomposites showed an interesting phase behavior (which was studied by combining DMTA and modulated DSC).     

外力辅助分散作用下环氧树脂粘土纳米复合材料中粘土的微观结构与解离机理研究

采用不同分散方法(机械搅拌、高速均质搅拌和球磨分散)制备环氧树脂粘土纳米复合材料,研究了分散方法对不同有机粘土解离结构和纳米复合材料力学性能的影响,并在此基础上探讨了粘土的解离机理.结果表明,普通机械搅拌只能使小粒径粘土或大粒径粘土团聚体的外部片层解离;施加一定的外力(如高速均质搅拌)促进粘土团聚体分散,有利于粘土片层的解离;利用剪切摩擦作用较强的球磨法分散粘土,不同处理剂改性粘土的内外片层都可以充分解离,而有机改性剂中酸性质子的催化作用对粘土片层解离的影响不大,只要粒径足够小,片层解离的驱动力(基体弹性力、反应性等)能够克服其所受阻力(片层引力、层外基体粘性阻力、层内粘性引力等),粘土内外各片层将会同时向外迁移而解离.纳米复合材料的力学性能大大改善,冲击强度和弯曲强度分别提高近50%和8%;     

Photostabilization of an entomopathogenic fungus using composite clay matrices

To provide photostabilization for entomopathogenic fungi by anionic dyes, composite matrices based on clay-biopolymer combinations were prepared. In the first step, the negative surface charge of various clays (montmorillonite, attapulgite, bentonite and kaolinite) was reversed to positive by adsorption to the polycationic biopolymer chitosan. The second step involved adsorption of the toxicologically safe anionic dyes fast green (FG) and naphthol yellow S (NYS) to the clay complexes. Compared with cytotoxic photoprotectants like berberine, palmatine and acriflavine, the anionic dyes have no adverse effects up to a concentration of 1 M. In assays using various clay-chitosan-dye matrices and UV irradiation from a lamp source, it was evident that both FG and NYS provided considerable photostabilization for conidia of the entomopathogenic fungus Aschersonia spp. that served as a model biocontrol agent. Apparently, because of the light-dispersing property, bentonite and attapulgite per se provided significant photoprotection. All clay matrices containing FG provided a substantial photostabilization effect.