辉光放电电解等离子体法制备VMT/P(AMPS-co-AA)高吸水树脂

在水溶液中,以蛭石(VMT)、2-丙烯酰胺-2-甲基丙磺酸(AMPS)和丙烯酸(AA)为原料,N,N'-亚甲基双丙烯酰胺(MBA)为交联剂,用辉光放电电解等离子体(GDEP)引发制备蛭石/聚(2-丙烯酰胺-2-甲基丙磺酸-co-丙烯酸)(VMT/P(AMPS-co-AA))复合高吸水树脂。考察了放电电压、放电时间、蛭石用量和交联剂含量对复合高吸水树脂吸水溶胀性能的影响,用FT-IR、XRD、TG、SEM对复合高吸水树脂的结构、形貌和热稳定性进行了表征,同时探讨了可能的引发聚合机理。结果表明, VMT 表面的羟基与AMPS和AA中的C=C键发生接枝共聚形成了无机/有机无定形共聚物,该材料表面呈现粗糙、多孔的三维网状结构,热稳定性良好,GDEP引发是一个自由基引发的链增长过程。     

高吸水树脂的UV固化合成及研究

采用UV固化法,以丙烯酸(AA)、丙烯酰胺(AM)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为单体,聚乙烯醇(PVA)为交联剂,合成出AA/AM/AMPS互穿网络型高吸水树脂,研究了反应条件对树脂吸水性能的影响,得到了较优的反应条件.通过FT-IR、SEM对树脂的分子结构及表面形态进行了表征.     

VMT/P(AMPS-co-AA)复合高吸水树脂的性能测试

研究了溶液pH、盐浓度对辉光放电电解等离子体引发合成的蛭石/聚(2-丙烯酰胺-2-甲基丙磺酸-co-丙烯酸) (VMT/P(AMPS-co-AA)) 复合高吸水树脂的溶胀行为的影响,考察了染料pH、吸附时间、染料浓度等因素对复合高吸水树脂吸附量的影响,同时对树脂的吸附-解吸性能进行了研究。结果表明, VMT/P(AMPS-co-AA)具有高吸水性、pH敏感性、盐敏感性以及高吸附性。该树脂在蒸馏水中的最大溶胀率达到822.4 g/g,对阳离子染料亚甲基蓝(MB)、结晶紫(CV)和孔雀石绿(MG)的吸附量分别可达2027.8, 2171.8和883.2 mg/g。在pH=6.5和25℃下,其对染料的吸附行为符合动力学准二级模型,该树脂还具有一定的吸附-解吸性能和重复利用性能。     

复配成孔剂对高吸水树脂吸液性能的影响

以丙烯酰胺(AM)、丙烯酸(AA)、2-丙烯酰胺-2-甲基丙磺酸(AMPS)为单体,过硫酸铵为引发剂,N,N-亚甲基双丙烯酰胺为交联剂,山梨醇酐单硬脂酸酯为分散剂,碳酸氢钠与丙酮为复配成孔剂,采用反相悬浮聚合法制备了AA/AM/AMPS多孔型高吸水树脂,并研究了成孔剂种类、复配成孔剂配比、水与环己烷质量比(简称水油比)、中和度、交联剂用量对高吸水树脂吸液性能的影响。结果表明:在水油比为1.0∶2.5,中和度为73%,交联剂用量为0.3%(w),碳酸氢钠与丙酮质量比为1.0∶1.5时,高吸水树脂的吸水倍率和吸盐倍率达到最高,分别为1732.5,142.9 g/g,且具有较好的保水性能。     

微波法制备高吸水性树脂的溶胀性能研究

以2-丙烯酰胺-2-甲基丙磺酸(AMPS)和丙烯酸(AA)为单体,N,N′-亚甲基双丙烯酰胺为交联剂,在不加引发剂的情况下采用微波聚合法合成了丙烯酸-2-丙烯酰胺-2-甲基丙磺酸二元共聚高吸水性树脂。研究了交联剂用量、中和度等因素对产物性能的影响,并对溶胀动力学进行了初步探讨。     

AMPS/AA-淀粉-有机蒙脱土复合高吸水树脂的性能表征

以丙烯酸和2-丙烯酰胺-2-甲基丙磺酸为单体接枝淀粉,以过硫酸铵为引发剂,N,N-亚甲基双丙烯酰胺为交联剂,添加经有机改性的钠基蒙脱土,采用水溶液聚合法制备了丙烯酸-2-丙烯酰胺-2-甲基丙磺酸-淀粉-有机蒙脱土复合高吸水树脂。探讨了聚合温度、AMPS单体用量和有机蒙脱土用量对高吸水树脂性能的影响。最佳反应条件下得到的产物吸水倍率达775g/g,吸盐水倍率达118g/g。利用红外光谱、X射线衍射和扫描电镜对产物组成和结构形貌进行表征。     

微波辐射CMC接枝AA/AMPS高吸水树脂的制备

采用微波辐射方法制备了羧甲基纤维素钠(CMC)接枝丙烯酸(AA)/2-丙烯酰胺基-2-甲基丙磺酸(AMPS)高吸水性树脂,并用红外光谱对树脂进行了表征。探讨了交联剂用量、引发剂用量、单体配比、中和度和微波功率对树脂吸水性能的影响。实验结果表明:最佳合成条件下制备的高吸水性树脂吸蒸馏水倍率达690g/g,吸生理盐水倍率为90g/g;红外光谱分析表明:丙烯酸和2-丙烯酰胺基-2-甲基丙磺酸接枝到羧甲基纤维素钠分子链上。     

纤维素基高吸水树脂的研究

本研究以羧甲基纤维素(CMC)、丙烯酸(AA)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为原料,用过硫酸钾(KPS)为引发剂,N,N'-亚甲基双丙烯酰胺(NMBA)为交联剂,并在丙烯酸聚合液中加入尿素,经接枝共聚制得了既具有吸水、保水能力,又具有肥效性且可缓释的吸水树脂,系统研究了分散时间、聚合温度、交联剂种类和用量、尿素用量等对该高吸水树脂性能的影响。结果表明,高吸水树脂的最佳制备工艺为:分散时间1.5 h,聚合温度75℃,交联剂NMBA用量为单体摩尔数的0.497%,尿素用量为16 g。缓释肥料的缓释性实验结果表明:缓释肥料中的氮具有缓释性。     

P(AA-co-AMPS)/Kaolin复合高吸水树脂的制备及结构性能研究

以丙烯酸(AA)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)和高岭土(Kaolin)为原料,采用溶液聚合法分别制备出聚丙烯酸(PAA)高吸水树脂、聚(丙烯酸-co-2-丙烯酰胺基-2-甲基丙磺酸)(P(AA-co-AMPS))高吸水树脂、P(AA-co-AMPS)/Kaolin复合高吸水树脂,并通过傅里叶变换红外光谱、扫描电镜、X射线衍射等测试方法对其结构与性能进行表征。结果表明:Kaolin与P(AA-co-AMPS)高吸水树脂之间为物理共混;PAA高吸水树脂、P(AA-co-AMPS)高吸水树脂和P(AA-co-AMPS)/Kaolin复合高吸水树脂的吸水倍率分别为231,323,357 g/g,吸盐水倍率分别为35.6,64.1,66.4 g/g,保水率分别为51.3%,55.6%,57.9%,凝胶形变量分别为3.75,4.10,2.23 mm;树脂的吸水速率由小到大依次为PAA高吸水树脂、P(AA-co-AMPS)高吸水树脂、P(AA-co-AMPS)/Kaolin复合高吸水树脂。     

VMT/P(AMPS-co-AA)复合高吸水树脂及其对染料吸附性能

研究了溶液p H、盐浓度对辉光放电电解等离子体引发合成的蛭石/聚(2-丙烯酰胺-2-甲基丙磺酸-co-丙烯酸)〔VMT/P(AMPS-co-AA)〕复合高吸水树脂的溶胀行为的影响,考察了染料p H、吸附时间、染料浓度等对树脂吸附量的影响,同时对树脂的吸附-解吸重复利用性能进行了测试。结果表明,VMT/P(AMPS-co-AA)具有高吸水性、p H敏感性、盐敏感性以及高吸附性。该树脂在蒸馏水中的最大溶胀率达到822.4 g/g,对阳离子染料亚甲基蓝(MB)、结晶紫(CV)和孔雀石绿(MG)的吸附量分别可达2 027.8、2 171.8和883.2 mg/g。在p H=6.5和25℃下,其对染料的吸附行为符合动力学准二级模型,该树脂还具有一定的吸附-解吸性能和重复利用性能。     

Quantification of Phospholipids Classes in Human Milk

Phospholipids are integral constituents of the milk fat globule membranes and they play a central role in infants’ immune and inflammatory responses. A methodology employing liquid chromatography coupled with evaporative light scattering detector has been optimized and validated to quantify the major phospholipids classes in human milk. Phospholipids were extracted using chloroform and methanol and separated on C18 column. Repeatability, intermediate reproducibility, and recovery values were calculated and a large sample set of human milk analyzed. In human milk, phospholipid classes were quantified at concentrations of 0.6 mg/100 g for phosphatidylinositol; 4.2 mg/100 g for phosphatidylethanolamine, 0.4 mg/100 g for phosphatidylserine, 2.8 mg/100 g for phosphatidylcholine, and 4.6 mg/100 g for sphingomyelin. Their relative standard deviation of repeatability and intermediate reproducibility values ranging between 0.8 and 13.4 % and between 2.4 and 25.7 %, respectively. The recovery values ranged between 67 and 112 %. Finally, the validated method was used to quantify phospholipid classes in human milk collected from 50 volunteers 4 weeks postpartum providing absolute content of these lipids in a relatively large cohort. The average content of total phospholipids was 23.8 mg/100 g that corresponds to an estimated mean intake of 140 mg phospholipids/day in a 4-week old infant when exclusively breast-fed.     

The hydration of reactive cement-in-polymer dispersions studied by nuclear magnetic resonance

The behaviour of two novel cement-in-polymer (c/p) dispersions, namely cement-in-poly(vinyl acetate) and cement-in-poly(vinyl alcohol) upon exposure to water at room temperature was investigated by a combination of various NMR methods. The swelling, cracking, and the water ingress were monitored non-destructively using ¹H single point imaging. The hydration of the cement matrix was investigated using ²⁹Si NMR whilst ¹³C CPMAS NMR spectra allowed the quantification of the kinetics of the hydrolysis reaction of poly(vinyl acetate) into poly(vinyl alcohol). The polymer controls the rate of water ingress and swelling which in turn determines the behaviour of the c/p dispersions upon exposure to water. For the cement-in-poly(vinyl alcohol), the rates of water ingress and swelling are much faster than the hydration of the clinker whilst for the cement-in-poly(vinyl acetate) the slow rates of the two processes allow the formation of a cementious matrix which assures the stability of the sample.     

Design and function of novel superplasticizers for more durable high performance concrete (superplast project)

In this article we shall describe our quest and ultimate success in furthering our understanding of the action of superplasticizers on the rheology of cement and concrete. By specifically producing superplasticizers with varied architectures, we have been able to show the important structural features of the macromolecules that lead to a successful superplasticizer or water reducing agent. Both polycarboxylate and lignosulfonate polymers have been investigated. Using both non-reactive model MgO powders, three different types of cement blends, the adsorption behaviour and the effect on the rheological properties of these two important superplasticizer families have been used to further develop a conceptual model for superplasticizer — cement behaviour. This paper will deal mainly with the conceptual model, the materials and methods used to asses the polymer adsorption behaviour and rheological properties of the systems studied. We shall briefly describe the adsorption of the polymers onto the different surfaces and their influence on surface charge and rheology and the influence of the various ionic species found in cement pore solutions that may influence polymer-cement affinity. The key factors are shown to be the effective adsorbed polymer thickness and the induced surface charge which can be influenced by the polymer architecture, the pore solution composition and the initial particle surface charge.     

Interactions between shrinkage reducing admixtures (SRA) and cement paste's pore solution

Shrinkage reducing admixtures (SRA) have been developed to combat shrinkage cracking in concrete elements. While SRA has been shown to have significant benefits in reducing the magnitude of drying and autogenous shrinkage, it has been reported that SRA may cause a negative side effect as it reduces the rate of cement hydration and strength development in concrete. To examine the influence of SRA on cement hydration, this study explores the interactions between SRA and cement paste's pore solution. It is described that SRA is mainly composed of amphiphilic (i.e., surfactant) molecules that when added to an aqueous solution, accumulate at the solution-air interface and can significantly reduce the interfacial tension. However, these surfactants can also self-aggregate in the bulk solution (i.e., micellation) and this may limit the surface tension reduction capacity of SRA. In synthetic pore solutions, SRA is observed to form an oil-water-surfactant emulsion that may or may not be stable. Specifically, at concentrations above a critical threshold, the mixture of SRA and pore fluid is unstable and can separate into two distinct phases (an SRA-rich phase and an SRA-dilute phase). Further, chemical analysis of extracted pore solutions shows that addition of SRA to the mixing water depresses the dissolution of alkalis in the pore fluid. This results in a pore fluid with lower alkalinity which causes a reduction in the rate of cement hydration. This may explain why concrete containing SRA shows a delayed setting and a slower strength development.     

Study of the hydration of CaO powder by gas–solid reaction

Hydration of CaO powders by reaction with water vapor has been studied in isothermal and isobaric conditions. Experimental tests were performed within the temperature range of 70 °C–420 °C and with a water vapor pressure from 5 to 160 hPa by means of a thermogravimetric device. Two powders, exhibiting slight differences in their physical properties, were studied. However, for one of the powders and under some temperature and pressure conditions, the reaction is not complete. The difference of behavior between both CaO powders was interpreted by considering the effect of the morphological properties on the mechanism of growth of Ca(OH)₂.     

The influence of water removal techniques on the composition and microstructure of hardened cement pastes

The removal of water from hardened cement paste for analysis or to arrest ongoing hydration has been reported to affect the composition of hydrated phases and microstructure. The effect that arresting the hydration of hardened cement paste by replacing the pore water with acetone before drying, and by removing the water by freeze, vacuum and oven drying has on the hardened cement paste has been investigated. Two pastes were studied, a cemented iron hydroxide floc where a high proportion of ordinary Portland cement (OPC) had been replaced by pulverised fuel ash, and a pure hydrated OPC. The results showed that none of the water removal techniques caused any major deterioration in the composition and microstructure of the hardened cement pastes studied, but the pores appeared better preserved after arresting hydration using acetone quenching. Freeze drying appeared to cause more cracking of the microstructure than the other water removal techniques.     

2-(2'-咪唑偶氮)萘酚-4-磺酸的合成及其分析性质的研究

合成了新显色剂咪唑偶氮－２－萘酚－４－磺酸（ＩＡＮ－４Ｓ）,研究了试剂的离解常数及其与金属离子的显色反应。     

Influence of bleed water reabsorption on cement paste autogenous deformation

The effects of bleed water reabsorption and subsequent early age expansion on observed autogenous deformation are investigated in this research. Bleeding was induced by varying superplasticizer and shrinkage-reducing admixture dosages and by increasing the water-to-cement ratio. This research revealed that significant early age expansion occurs with increasing chemical admixture dosages and higher water-to-cement ratios, as expected, due to increasing bleeding of those samples. When samples were rotated, negligible early age expansion was observed. Thus, bleed water reabsorption is shown to be the primary mechanism causing initial expansion in sealed autogenous deformation samples. Thermal dilation and ettringite growth appear to have a minimal influence on the observed expansion. Rotating the samples during setting eliminates the potential for bleed water reabsorption and is recommended for all autogenous deformation testing.     

Comparison between surface and bulk hydrophobic treatment against corrosion of galvanized reinforcing steel in concrete

The effectiveness of bulk hydrophobic treatment against corrosion of galvanized steel reinforcement in concrete specimens with w/c = 0.45 and w/c = 0.75 was compared with that of surface treatment, even in the presence of cracks 0.5 and 1 mm wide in the concrete cover. In this case surface hydrophobic treatments were applied both before and after cracking as a preventive and a restorative method against reinforced concrete deterioration, respectively. The obtained results in terms of water absorption, electrochemical measurements, chlorides penetration, and visual observations carried out on reinforced concrete specimens during the exposure to wet–dry cycles in 10% NaCl solution showed that bulk hydrophobization is the most effective treatment in improving the corrosion resistance of galvanized steel reinforcements in concrete also in the presence of cracks. Surface hydrophobization is very effective just in the first few exposure cycles to the aggressive environment and when used as a restorative method which is able to cancel the deleterious effect of cracks only 0.5 mm wide.     

Effect of plasma treatment of polymeric tape carriers on wetting behaviour of aqueous ceramic tape casting slurry

Due to environmental and health aspects, aqueous ceramic slurries are preferred to traditional organic solvent systems in tape casting. An important obstacle associated with the high surface energy of water is poor wetting of aqueous ceramic slurries on polymeric tape carriers. Therefore, we measured the contact angles of an aqueous epoxy-based ceramic slurry on polyethylene terephtalate (PET), polypropylene (PP), polymethyl methacrylate (PMMA), and aluminium-coated polyethylene terephtalate (PET-Al) films and investigated approaches to improving their wetting. We evaluated the effect of plasma treatment of the tape carrier surface on the wetting behaviour and compared it with the effect of adding non-ionic amphiphilic surfactants to the ceramic slurry. The treatment of the tape carrier surface by low-temperature plasma substantially improved the wetting behaviour of aqueous ceramic slurry. The lowest contact angle of 31° was obtained on the PET film. Although the addition of non-ionic surfactants improved both the wetting behaviour of the slurry and the detachment of the polymeric carrier from the ceramic tape even better than the plasma treatment of the carrier surface did, the plasma-treated carriers still present a useful alternative to the surfactants. In the case of the plasma-treated PET carrier the surfactants could be fully eliminated and potential drawbacks related to the use of surfactants could be prevented.