Magnetocaloric properties of phenolic resin bonded La(Fe,Si)13-based plates and its use in a hybrid magnetic refrigerator

We present a simple hot press-based method for processing La(Fe,Si)13-based compounds consisting of La–Fe–Co–Si–C particles and phenolic resin. The magnetic entropy change △S per unit mass for the La Fe_(10.87)Co_(0.63)Si_(1.5)C_(0.2)/phenolic resin compounds have nearly the same magnitude with the base materials. With the content of phenolic resin of 5.0 wt%, the compound conductivity is 3.13 W·m^(-1)·K^(-1). In order to measure the cooling performance of La(Fe,Si)13-based compounds,the La(Fe_(11.6-x)Co_(x))Si_(1.4)C_(0.15)(x =0.60, 0.65, 0.75, 0.80, 0.85)/phenolic resin compounds were pressed into thin plates and tested in a hybrid refrigerator that combines the active magnetic refrigeration effect with the Stirling cycle refrigeration effect. The test results showed that a maximum cooling power of 41 W was achieved over a temperature span of 30 K.

Synthesis and Adsorption Studies on Magnetic Microbeads of Polythioether-arylamine Resins

By the suspended condensation reaction of poly(choloromethylthiirane)with o-tolidine and o- dianisidine respectively, two newmicrobeads chelating resins were synthesized by usingγ-Fe_2O_3 asmagnetic core. Their adsorption properties for Hg(Ⅱ), Cu(Ⅱ), Zn(Ⅱ), Pb(Ⅱ), Au(Ⅲ), Pd(Ⅱ), Pt (Ⅳ)and Ag(Ⅰ)were investigated. Themicrobeads posses excellent adsorbability for Hg(Ⅱ) and noble metalions, and predominantly adsorbed Pd(Ⅱ)or Hg(Ⅱ)in the coexistence ofCu(Ⅱ), Zn(Ⅱ)and Mg(Ⅱ).

3D printing of high-precision and ferromagnetic functional devices

The development of projection-based stereolithography additive manufacturing techniques and magnetic photosensitive resins has provided a powerful approach to fabricate miniaturized magnetic functional devices with complex three-dimensional spatial structures.However,the present magnetic photosensitive resins face great challenges in the trade-off between high ferromagnetism and excellent printing quality.To address these challenges,we develop a novel NdFeB-Fe_(3)O_(4) magnetic photosensitive resin comprising 20 wt.%solid loading of magnetic particles,which can be used to fabricate high-precision and ferromagnetic functional devices via micro-continuous liquid interface production process.This resin combining ferromagnetic NdFeB microparticles and strongly absorbing Fe_(3)O_(4) nanoparticles is able to provide ferromagnetic capabilities and excellent printing quality simultaneously compared to both existing soft and hard magnetic photosensitive resins.The established penetration depth model reveals the effect of particle size,solid loading,and absorbance on the curing characteristics of magnetic photosensitive resin.A high-precision forming and ferromagnetic capability of the NdFeB-Fe_(3)O_(4) magnetic photosensitive resin are comprehensively demonstrated.It is found that the photosensitive resin(NdFeB:Fe_(3)O_(4)=1:1)can print samples with sub-40μm fine features,reduced by 87%compared to existing hard magnetic photosensitive resin,and exhibits significantly enhanced coercivity and remanence in comparison with existing soft magnetic photosensitive resins,showing by an increase of 24 times and 6 times,respectively.The reported NdFeB-Fe_(3)O_(4) magnetic photosensitive resin is anticipated to provide a new functional material for the design and manufacture of next-generation micro-robotics,electromagnetic sensor,and magneto-thermal devices.

Preparation and Characterization of Magnetic Resin Made from Chitosan and Cerium

In this study,the water-based ferromagnetic fluid and magnetic resin made from chitosan and cerium complex(MRCCC)were successfully prepared by using the chemical co-precipitation technique and by the reversed-phase suspension cross-linkingpolymerization.MRCCC presented uniform and narrow particle size distribution as determined by the Laser Particles Sizer.TheInductively Coupled Plasma-Atomic Emission Spectrometry(ICP-AES),Fourier transform infrared spectroscopy(FT-IR),differen-tial scanning calorimetry(DSC)and X-ray powder diffraction(XRD)study demonstrated that there were iron and cerium existing inMRCCC.The movement of MRCCC under magnetic field proved its magnetic property.The swelling kinetics in water or solutionswith different pH indicated that MRCCC could be applied in solutions with pH greater than 1.0.The ferromagnetic fluid particleswere stable in MRCCC soaked in solutions with pH>2.0.In view of these results,MRCCC can be used as material for separation,clarification,adsorption,sustained release and hydrolysis activity.

STUDY ON MAGNETIC CHELATING RESIN Ⅰ.PREPARATI0N OF PEI2 AND ITS ADSORPTION PROPERTIES TO METAL IONS

Magnetic polyethyleneimine chelating resin (PEI2) wasprepared. Its average diameter was 0. 44mm and it contained magnetic particles over 11% of the microcapsules after it had been treated with 8% hot HC1. The results showed that the reaction media had significant effect on physical forms, magnetic particles content and stability in acid of the microcapsules. PEF2 had very high adsorption capacity to Au3+ , Pd2+ and Hg2+ , and little one tmvards Mg2+, Pb2+ and Cu2+. It was discovered that PEI2 could reduce Au3+ into elemental gold.

STUDY ON MAGNETIC CHELATING RESIN Ⅱ.PREPARATION OF PSE2 AND ITS ADSORPTION PROPERTIES TO METAL IONS

Magnetic polythioether chelating resin (PSEZ) was pre-pared. Its average diameter was 0. 25mm and it contained magnetic parti-cles over 2,2% of the microcapsules after it had been treated with 2N hot HCl , and it ivould be destroyed in 5N hot HCl, The results showed that reaction medium had remarkable effect on physical forms of the microcap-sules. PSEZ had very high adsorption capacity to Au3+ and Hg2+, and little one towards Mg2+ , Pb2+. It was discovered that PSEZ could reduce Au3+ into elemental gold and Pti+to Pb2+.

Combination of chlorine and magnetic ion exchange resin for drinking water treatment of algae

The effectiveness of a magnetic ion exchange resin(MIEX) for the treatment of Hongze Lake water in China was evaluated.The kinetics of natural organic matter(NOM) removal at various MIEX doses and contact time,multiple-loading experiments,impacts of MIEX prior to coagulation on coagulant demands and the effectiveness of combination of MIEX,pre-chlorination and coagulation were investigated.Kinetic experimental results show that more than 80%UV254 and 67%dissolved organic carbon(DOC) from raw water can be removed by the use of MIEX alone.94%sulfate,69%nitrate and 98%bromide removals are obtained after the first use of MIEX in multiple-loading experiments.It is suggested that MIEX can be loaded up to 1 250 bed volume(BV,volume ratio of tested water to resin) or more without saturation when regarding organics removal as a target. MIEX can remove organics to a greater extend than coagulation and lower the coagulant demand when combining with coagulation. Chlorination experimental results show that MIEX can remove 57%chlorine demand and 77%trihalomethane formation potential(THMFP) for raw water.Pre-chlorination followed by MIEX and coagulation can give additional organic and THMFP removals.The results suggest that MIEX provides a new method to solve the problem algae reproduction.

17α-Ethinylestradiol removal from water by magnetic ion exchange resin

Magnetic ion exchange(MIEX) resins have received considerable attention in drinking water treatment due to their fast and efficient removal of dissolved organic carbon(DOC). Two types of mechanisms, i.e., ion exchange,reversible and irreversible adsorption, may occur during pollutants removal by MIEX. This work examined the removal mechanism of 17α-Ethinylestradiol(EE2) by MIEX. As one of typical estrogen micro-pollutants,EE2 existed as neutral molecule in natural water, and its charge density was close to zero [(0.00000219 ±0.00000015) meq·(μg EE2)^(-1)] based on the potentiometric titration method. However, the removal of EE2 by MIEX was much higher than that of other micro-pollutants previously reported. Multi-cycle adsorptionregeneration experiments and ion exchange stoichiometry analysis were conducted to elucidate the removal mechanism of EE2 by MIEX resin. The results suggested that the main removal mechanism of EE2 by MIEX was ion exchange instead of reversible micro-pore adsorption. The experimental analysis based on Donnan theory indicated that the internal micro-environment of resin beads was alkaline, in the alkaline environment EE2 would be ionized into negatively charged groups. As a result, ion exchange reaction occurred inside the pore of MIEX resin, and the removal process of EE2 by MIEX was dominated by the ion exchange reaction.

Effect of bonding process on the properties of isotropic epoxy resin-bonded Nd-Fe-B magnets

Bonded NdFeB magnets were prepared by compression molding. The effect of preparation technology on their magnetic and mechanical properties was studied through the analysis of density, Br, Hcj, （BH）max, bending strength, and compressive strength of the bonded magnets. The results showed that the magnetic properties decreased with increasing binder content, whereas the mechanical properties increased. Br and （BH）max increased with rising pressure, whereas Hcj decreased. For a fixed mass fraction of the binder, the optimal pressure was 620 MPa and the best thermosetting temperature was 160°C. These conditions made the bonded magnets have the optimal mechanical properties. Scanning electron microscopy （SEM） analyses of the fracture surfaces indicated that the epoxy resin bonded magnets exhibited brittle behavior.

Influence of acrylamide monomer addition to the acrylic denture-base resins on mechanical and physical properties

The aim of the study was to evaluate the effect of adding acrylamide monomer （AAm） on the characterization, flexural strength, flexural modulus and thermal degradation temperature of poly（methyl methacrylate） （PMMA） denture-base resins. Specimens （n= 10） were fabricated from a conventional heat-activated QC-20 （Qc-） and a microwave heat-activated Acron MC （Ac-） PMMA resins. Powder/ liquid ratio followed the manufacturer＇s instructions for the control groups （Qc-c and Ac-c） and for the copolymer groups, the resins were prepared with 5% （-5）, 10% （- 10）, 15% （- 15） and 20% （-20） acrylamide contents, according to the molecular weight ratio, respectively. The flexural strength and flexural modulus were measured by a three-point bending test. The data obtained were statistically analyzed by Kruskal-Wallis test （a=O.05） to determine significant differences between the groups, The chemical structures of the resins were characterized by the nuclear magnetic resonance spectroscopy. Thermal stabilities were determined by thermogravimetric analysis （TGA） with a heating rate of 10 ~C.min-1 from 35 ~C to 600 ~C. Control groups from both acrylic resins showed the lowest flexural strength values. Qc-15 showed significant increase in the flexural strength when compared to Qc-c （P〈O.01）. Ac-10 and Ac-15 showed significance when compared to Ac-c （P〈O.01）. Acrylamide incorporation increased the elastic modulus in Qc-10, Qc-15 and Qc-20 when compared to Qc-c （P〈0.01）. Also significant increase was observed in Ac-10, Ac-15 and Ac-20 copolymer groups when compared to Ac-c （P〈0.01）. According to the 1H-nuclear magnetic resonance （NMR） results, acrylamide copolymerization was confirmed in the experimental groups. TGA results showed that the thermal stability of PMMA is increased by the insertion of AAm.

粉煤灰磁珠对环氧树脂聚合物阻燃性能的影响

为了实现粉煤灰固体废弃物的资源化利用,从粉煤灰中分选出元素含量不同的磁珠(MSs),探究MSs添加量和MSs中Fe元素含量对环氧树脂(epoxy resin,EP)阻燃性能的影响。采用锥形量热仪(CC)、热重分析(TG)等测试手段对MSs/EP复合材料的阻燃性能进行测试。研究结果表明:随着粒径减小,磁珠中的Fe元素含量从55.73%升高至64.83%。当MSs添加量分别为2 wt%,4 wt%,6 wt%,8 wt%和10 wt%时,复合材料的耐火性能先升高后下降;当MSs中Fe元素含量分别为55.73%,57.06%,60.35%和64.83%时,复合材料的耐火性能单调升高。与纯EP相比,当MSs添加量为6 wt%,Fe元素含量为64.83%时,MSs/EP复合材料的热释放速率峰值p-HRR降低39.6%,总热释放量THR降低30.7%,火灾性能指数FPI提高53.73%,阻燃指数FRI从1提高至3.118,火灾增长指数FGI降低51.96%,残炭率提高47.5%。MSs/EP良好的阻燃性能主要归因于MSs能够催化EP形成连续稳定的炭层,从而隔绝热量和氧气,降低复合材料的燃烧强度。研究结果可提高粉煤灰磁珠的高附加值利用,同时为低成本阻燃聚合物提供参考。

磁性二氧化硅纳米线的制备及其对环氧树脂的增韧效果

以反相微乳液法制备的二氧化硅纳米线(SiO_(2)NW)为基础,采用原位化学氧化共沉淀法在二氧化硅纳米线表面生长四氧化三铁,制备了表面负载四氧化三铁的磁性二氧化硅纳米线(SiO_(2)NW@Fe_(3)O_(4))。利用X射线衍射仪、傅立叶变换红外光谱仪、X射线光电子能谱仪、扫描电子显微镜研究了SiO_(2)NW和SiO_(2)NW@Fe_(3)O_(4)的结构和形貌。通过机械搅拌和超声分散将SiO_(2)NW@Fe_(3)O_(4)均匀分散在环氧树脂中,在微磁场环境中对环氧树脂进行固化,并对固化后涂层的力学性能进行测试。结果表明:与纯环氧树脂相比,添加磁性二氧化硅纳米线并在微磁场环境中固化后,环氧树脂的拉伸强度、冲击强度和断裂韧性分别提高了59.1%、98.5%和135.0%。磁性二氧化硅纳米线在环氧树脂中向特定方向排列,改善了环氧树脂特定方向的力学性能。

预浸料树脂含量核磁共振测试方法研究

核磁共振法作为一种新型快速检测技术,在预浸料生产过程中可用于对预浸料树脂含量进行快速、准确的检测,对预浸工艺进行及时调整从而提升产品整体质量。目前最广泛使用的预浸料树脂含量测定方法为溶洗法。本文以溶洗法测试结果作为参考,与核磁法测得的树脂含量结果进行对比分析,验证了利用核磁共振原理测试预浸料树脂含量的可行性。

环氧酚醛树脂粉除磁提纯实验研究

采用HCT300型电磁干粉除铁器对酚醛树脂进行除磁研究,考察主要操作参数对除磁效果的影响。电磁干粉除铁器具有操作简单、智能化程度高、除磁效果明显等优势,在使用该设备时调整好设备的磁场强度、介质间隙、介质振幅等关键参数,可以设备的磁选性能更加明显。针对济南某用户的酚醛树脂原料含铁量为10.63ppm,物料粒度60目全通,需要的磁选最佳条件为:磁场强度0.65T,介质间隙10mm,振幅在1.2mm,经HCT300型电磁干粉除铁器一次分选,可获0.93ppm的优质酚醛树脂。

Selection of magnetic anion exchange resins for the removal of dissolved organic and inorganic matters

Four magnetic anion exchange resins （MAERs） were used as adsorbents to purify drinking water. The effect of water quality （pH, temperature, ionic strength, etc.） on the performance of MAER for the removal of dissolved organic matter （DOM） was also investigated. Among the four studied MAERs, the strong base resin named NDMP- 1 with high water content and enhanced exchange capacity exhibited the highest removal rate of dissolved organic carbon （DOC） （48.9% removal rate） and UV-absorbing substances （82.4% removal rate） with a resin dose of 10 mL/L after 30 rain of contact time. The MAERs could also effectively remove inorganic matter such as sulfate, nitrate and fluoride. Because of the higher specific UV absorbance （SUVA） value, the DOM in the raw water was found to be removed more effectively than that in the clarified water by NDMP resin. The temperature showed a weak influence on the removal of DOC from 6 to 26℃, while a relatively strong one at 36℃. The removal of DOM by NDMP was also affected to some extent by the pH value. Moreover, increasing the sulfate concentration in the raw water could decrease the removal rates of DOC and UV-absorbing substances.

磁性阴离子交换树脂对水体中环丙沙星的吸附行为研究

制备不同Fe_(3)O_(4)含量的丙烯酸系强碱阴离子交换树脂为吸附剂,去除水环境中的环丙沙星(CPX),考察了不同Fe_(3)O_(4)含量的阴离子交换树脂对CPX的吸附行为。结果表明,树脂吸附使其准一级动力学和准二级动力学常数都有所增加,更符合一级动力学方程,R2>0.996,树脂中Fe_(3)O_(4)含量增加可增强吸附性能;Langmuir模型和Freundlich模型对系列树脂吸附CPX的过程均有较好的拟合效果,相关系数R^(2)>0.93,树脂中Fe_(3)O_(4)含量的变化不会改变树脂对CPX的吸附机制;pH值<6.18时,吸附量逐渐增加,pH值在6~8之间时,吸附量最高,当pH>8.76时,吸附量下降明显。较高Fe_(3)O_(4)含量的磁性丙烯酸系阴离子交换树脂受NaCl影响较大。

不同原料摩尔比对多元共缩聚树脂木材胶黏剂结构与性能的影响

以三聚氰胺(M)、苯酚(P)、尿素(U)、乙二醛(G)为原料,在弱酸性条件下合成了不同原料摩尔比的三聚氰胺–苯酚–尿素–乙二醛(MPUG)多元共缩聚树脂,对树脂的基本性能、润湿性能和胶合性能进行测试,据此优选出共缩聚树脂合成的较佳原料摩尔比;并采用傅里叶变换红外光谱、13C核磁共振波谱及X-射线光电子能谱对树脂结构进行表征。结果表明:M和P的加入能大幅提高树脂的胶合性能特别是耐水性;以原料摩尔比M∶P∶U∶G为0.2∶0.1∶1.0∶1.4的MPUG树脂制备的三层杨木胶合板胶合性能较优,其干状胶合强度、冷水24 h湿强度和63℃热水3 h湿强度分别为1.62、0.75、0.43 MPa,且无甲醛释放,可在干燥状态下直接室内使用。

Dissolved organic matter removal using magnetic anion exchange resin treatment on biological effluent of textile dyeing wastewater

This study investigated the removal of dissolved organic matter（DOM） from real dyeing bio-treatment effluents（DBEs） with the use of a novel magnetic anion exchange resin（NDMP）.DOMs in two typical DBEs were fractionized using DAX-8/XAD-4 resin and ultrafiltration membranes. The hydrophilic fractions and the low molecular weight（MW）（〈3 kDa） DOM fractions constituted a major portion（〉50%） of DOMs for the two effluents. The hydrophilic and low MW fractions of both effluents were the greatest contributors of specific UV254absorbance（SUVA254）,and the SUVA254 of DOM fractions decreased with hydrophobicity and MW. Two DBEs exhibited acute and chronic biotoxicities. Both acute and chronic toxicities of DOM fractions increased linearly with the increase of SUVA254 value. Kinetics of dissolved organic carbon（DOC） removal via NDMP treatment was performed by comparing it with that of particle active carbon（PAC）. Results indicated that the removal of DOC from DBEs via NDMP was 60%,whereas DOC removals by PAC were lower than 15%. Acidic organics could be significantly removed with the use of NDMP. DOM with large MW in DBE could be removed significantly by using the same means. Removal efficiency of NDMP for DOM decreased with the decrease of MW. Compared with PAC,NDMP could significantly reduce the acute and chronic bio-toxicities of DBEs. NaCl/NaOH mixture regenerants,with selected concentrations of 10% NaCl（m/m）/1%NaOH（m/m）,could improve desorption efficiency.

Efficient adsorption and desorption of Cu^(2+) by a novel acid-resistant magnetic weak acid resin

A novel magnetic weak acid resin NDMC-1 was prepared in the presence of methyl acrylate （MA）, divinylbenzene （DVB） and titanate coupling agent （TCA） coated γ-Fe203 particles. To evaluate the adsorption of Cu^2＋ on the obtained resin NDMC- 1, another two magnetic resins NDMC-0 （the precursor of NDMC-1 without hydrolyzation） and NDMO-1 （the synthesized weak acid resin using oleic acid coated γ-Fe2O3） were chosen for comparison. The results showed that the carboxyl groups were formed after hydrolyzation, and NDMC-1 exhibited a greater adsorption capacity to Cu2~. The desorption experiment demonstrated that the desorption ratio at pH 2 （95.14%） was greatly higher than pH 3 （25.97%）. Moreover, the magnetic resin NDMC-1 was proved to be stable at pH 2, extending the application of magnetic materials which were always considered to be acid-nor, resistant.

NiMnGa合金/环氧树脂复合材料力磁耦合细观模型的建立及应力-应变关系模拟

基于热力学理论和等效夹杂原理建立了包含机械能、化学自由能、磁晶各向异性能、Zeeman能和再取向过程硬化函数的NiMnGa合金/环氧树脂(NiMnGa/ER)复合材料的力磁耦合细观模型,模拟了零场下复合材料的应力-应变曲线,并与试验结果进行对比,最后预测了不同磁场强度(0~1.8 T)和磁场角度(与应力方向的夹角,0°,45°)下复合材料的应力-应变曲线。结果表明:模拟得到复合材料中马氏体变体再取向和逆再取向的临界应力分别为39.2,41.8 MPa,与试验结果的相对误差均不大于1.2%,验证了模型的准确性。磁场角度为45°下复合材料的应力-应变迟滞环比磁场角度0°下更大;当磁场角度为0°时,磁场强度越大,应力-应变迟滞环越大。