改性剂种类对羰基铁粉填充天然橡胶磁流变性能的影响（英文）

采用4种改性剂离子液体、硅烷偶联剂、油酸及硬脂酸改性羰基铁粉,以天然橡胶作为基质,研究了不同改性剂对天然橡胶基磁流变弹性体(MRE)磁流变性能的影响。结果表明,改性剂能明显提高天然橡胶基MRE的磁流变效应,其中油酸改性后的MRE的相对磁流变效应比未改性者提高了229%。扫描电镜照片显示改性后MRE中的磁性粒子呈现出定向链状结构,链段变得更加完整。     

各向同性与各向异性天然橡胶磁流变弹性体的导热性能及磁流变性能（英文）

采用羰基铁粉粒子填充天然橡胶磁流变弹性体(MRE),研究了各向同性与各向异性MRE的磁流变性能及导热性能。结果表明,各向异性MRE的热扩散系数和导热系数比各向同性MRE分别提高了30. 1%和41. 9%。同时,随着应变的增大,MRE的相对磁流变效应呈下降趋势,而在相同应变下,各向异性MRE的储能模量以及相对磁流变效应均高于各向同性MRE。     

磁流变弹性体的性能研究

以天然橡胶为基体制备磁流变弹性体（MRE），研究MRE的Payne效应及磁感应强度和磁流变效应。电子显微镜分析得出，对于羰基铁粉质量分数最大（81.67%）的MRE，羰基铁粉分布密集，出现羰基铁粉团聚现象。流变仪测试结果表明：随着羰基铁粉质量分数的增大，MRE的Payne效应和磁流变效应增强；随着应变的增大，MRE的储能模量减小，损耗因子增大。     

Fe-Si粒子填充顺丁橡胶复合材料的磁流变性能（英文）

制备了Fe-Si和羰基铁粉(CIP)粒子填充顺丁橡胶(BR)基磁流变弹性体(MRE),研究了2种粒子对BR基MRE磁流变性能和力学性能的影响。结果表明,随着应变的上升,MRE的相对磁流变性能呈下降趋势,在相同应变下,Fe-Si粒子填充BR基MRE的相对磁流变效应大于CIP填充的MRE;与BR/CIP相比,BR/Fe-Si的拉伸强度、300%定伸应力及扯断伸长率明显下降。     

PVC基磁流变弹性体的制备及性能表征

制备了以聚氯乙烯(PVC)糊树脂为基体的磁流变弹性体(MRE);研究了其静态力学性能、动态力学性能、SEM形貌和热降解性能.实验结果表明:PVC基磁流变弹性体的断裂强度随铁粉含量呈现出先上升后下降的趋势,磁致模量、相对磁流变效应和损耗因子均随铁粉含量的增加而增大,损耗因子几乎不依赖于磁场强度.当铁粉质量分数为80％时,最大磁致模量为1.06 MPa,损耗因子最大为0.35.TGA结果说明:随着铁粉含量的增加,PVC基MRE的热降解趋势增强.     

羰基铁粉填充天然橡胶基磁流变弹性体的性能

以天然橡胶（NR）为基体,考察了4种牌号（EW、SM、SQ、CN）的羰基铁粉对NR混炼胶的硫化特性及NR基磁流变弹性体（MRE）在压缩状态下的磁流变性能、物理机械性能、热稳定性及微观形态的影响。结果表明,EW、SM、SQ、CN的平均粒径依次增大,且CN具有最宽的粒径分布,EW具有最窄的粒径分布;在4种牌号的羰基铁粉中,SM填充NR混炼胶的焦烧时间和正硫化时间最短,硫化速率最快;随着羰基铁粉粒径的增加,NR混炼胶的交联密度增大,在硫化过程中均出现的硫化返原程度加剧;SM填充MRE的磁流变效应最高,CN填充MRE的磁流变效应最低;随着羰基铁粉粒径的增加,MRE的邵尔A硬度无明显变化,300%定伸应力呈上升趋势,拉伸强度和扯断伸长率都有所降低,其中CN填充MRE的耐热稳定性最好;在4种牌号的羰基铁粉填充MRE中,CN和SQ的整体粒径较大,且CN有较明显的块状团聚,而SM和EW的整体粒径较小。     

羰基铁粉/天然橡胶磁流变弹性体的结构与性能

研究了羰基铁粉含量和硫化温度对天然橡胶基磁流变弹性体（MRE）结构和性能的影响。结果表明,随着羰基铁粉用量的增加,MRE的交联密度降低,硫化速率提高,硫化胶的拉伸强度和扯断伸长率明显下降,胶料的热稳定性提高;随着硫化温度的升高,MRE的焦烧时间缩短,硫化返原现象严重,128℃下制备的MRE中羰基铁粉的链状结构最为明显,143℃下则不呈链状结构;在硫化温度128℃、羰基铁粉用量为60份时,制得的MRE的磁流变效应最高,达到48.9%。     

改性羰基铁粉对天然橡胶基磁流变弹性体性能的影响

选取离子液体1-烯丙基-3甲基咪唑氯(AMI)、硅烷偶联剂γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(KH570)、油酸(OA)和硬脂酸(SA)改性羰基铁粉(CIP)粒子,研究了改性羰基铁粉对天然橡胶(NR)基磁流变弹性体(MRE)力学性能、微观结构、磁流变性能和热稳定性的影响。结果表明:加入改性剂后,磁性颗粒在橡胶基体中排列更加规整,团聚减少,MRE相对磁流变效应均有上升,并且OA的改性效果最好;改性羰基铁粉填充NR基MRE的的热稳定性降低。     

磁流变弹性体的裂纹增长

各向同性的磁流变弹性体(MRE)在撕裂分析仪上拉伸时可以观察到单边缺口(SEN)与参比材料相比,MRE具有较低的裂口增长速度和更好的耐疲劳性。MRE性能的提高归功于基体配方的不同,而基体配方影响着复合材料的弹性。不过,显而易见,加入磁性粒子在短期内不会使复合材料变差或者导致局部应力集中,使裂纹增长,从而缩短材料的寿命。     

磁流变液材料的研究进展和应用前景

从材料的角度较为全面地综述了国内外磁流变液的研究状况,评述了国内外对磁流变材料的主要研究热点,内容涉及磁流变液的流变机理、性能以及磁性粒子、载液和添加剂等组成对磁流变液性能的影响,并展望了其应用前景。     

Dynamic mechanical properties of magnetorheological elastomers based on polyurethane matrix

Magnetorheological elastomers (MRE) are mainly composed of soft magnetic particles and rubber‐like matrix. Previous studies have shown that the matrix has a greater impact on mechanical properties of MRE. In this article, a new kind of polyurethane material was fabricated and used as the matrix of MRE. The effect of several factors on the mechanical properties of MRE samples was experimentally studied, such as fabrication condition, content of iron particles, different weight ratio of castor oil and diphenylmethane diisocyanate, plasticizer. Their microstructures were observed, and the mechanical properties were measured using a testing system in the presence of an external magnetic field. The experimental results demonstrate that these factors have different impact on shear storage modulus, magneto‐induced modulus, MR effect and damping property. In addition, the damping property of these MRE is also higher than that of MRE based on the other matrix. This study can hopefully be applied to optimize the mechanical properties of MRE. POLYM. COMPOS., 37:1587–1595, 2016. © 2014 Society of Plastics Engineers     

Surface polymerization of iron particles for magnetorheological elastomers

Magnetorheological Elastomers (MREs) are synthesized from silicone RTV (room temperature vulcanizing) elastomer with magnetically soft iron particles. The iron particle concentration of the MREs is 70 wt %. To reduce the effect of oxidation on the MREs, the ATRP technique is used for surface polymerization of iron particles with fluorinated styrene as monomer. The mechanical properties of MREs are characterized using a mechanical testing instrument, and the surface coated polymer is characterized using Fourier transform infrared spectroscopy (FTIR), X‐ray energy dispersive spectrometry (XEDS), differential scanning calorimetry (DSC), and the alignment of iron particles within MRE was characterized using scanning electron microscopy (SEM). The MRE samples are characterized using the mechanical testing instrument at 0 Tesla (off–state) and applied magnetic field from 0.46 Tesla to 0.62 Tesla (on–state). The required force at 0.62 Tesla increased approx. 3% to achieve 20% strain after 72 h of oxidation for surface coated MRE. On the other hand, the required force for non‐surface coated MREs at 0.62 Tesla increased up to 17% to achieve 20% strain after 72 h of oxidation. MREs with surface coated iron particles have higher oxidation stability based on the force–displacement test results, and MREs have excellent potential to be used as intelligent materials with high durability for a vibration isolator. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Magnetic (ethylene–octene) elastomer composites obtained by extrusion

Most research on magnetorheological elastomer (MRE) composites is focused on achieving the best magnetic and magnetorheological properties of composites. Less attention is paid to obtain adequate strength properties. The aim of this study was to receive MRE composites with the best mechanical characteristics. Thermoplastic ethylene–octene rubber composites, filled with different magnetoactive particles were reported. The use of extrusion method instead of traditional preparation processes (two‐roll mill, mixer) of composites was also presented. Ferromagnetics: micro‐ and nano‐sized iron oxides, as well as gamma iron oxide and carbonyl iron powder were found to be an active fillers improving both mechanical and magnetic properties of rubber. Application of extrusion process affected mechanical properties of MRE composites and the dispersion of magnetic fillers. Dynamic mechanical analysis (DMA) indicates the presence of strongly developed secondary structure in vulcanizates. Studies investigated by vibration sample magnetometer (VSM) proved that all composites exhibit adequate magnetic properties, predispose them for plenty of applications with the most promising being nowadays tunable vibration absorbers. POLYM. ENG. SCI., 57:520–527, 2017. © 2016 Society of Plastics Engineers     

Effects of magnetic field input cycle and peptizer on the MR effect of magneto‐rheological elastomer based on natural rubber

The magneto‐rheological (MR) effect of magneto‐rheological elastomers (MREs) depends on the degree of orientation of carbonyl iron particles, which are dispersed in the elastomeric matrix. In this study, viscosity and molecular weight of NR matrix decreased with the addition of peptizer, and resulted in an increase of MR effect because of the efficient orientation of carbonyl iron particles. Also, the optimum conditions for applying a magnetic field to orient carbonyl iron particles were defined by the input duration time of the magnetic field, rather than the number of input times. Ideal input duration time to induce the orientation of carbonyl iron particles on the elastomeric matrix was 15 minutes. In this system, the MR effect of MRE decreased significantly above 20,000 cycles of cyclic deformation because of interfacial failure between the carbonyl iron particles and the matrix. It was expected that the dynamic property of MRE would increase if the interfacial interaction between carbonyl iron particles and the matrix improved. POLYM. ENG. SCI., 55:2669–2675, 2015. © 2015 Society of Plastics Engineers     

Magnetorheological elastomers based on isobutylene–isoprene rubber

Magnetorheological (MR) elastomers are a group of smart materials whose modulus can be controlled by the application of an external magnetic field. In this paper, MR elastomers based on isobutylene–isoprene rubber were prepared by the common manufacturing procedure of rubber and the corresponding MR effect, mechanical properties, and thermal stability were investigated. The results showed that MR effect varied with the volume content of iron particles and a maximum of 20% in MR effect was obtained at 15 vol% of iron particles. The relationship between MR effect and microstructure was discussed in detail. Mechanical tests showed that iron particles could improve the tensile strength and hardness. However, compared with carbon black with the same volume content, the reinforcing effect was far worse. TG analysis showed the thermal stability of isobutylene–isoprene rubber was improved by incorporation of iron particles. POLYM. ENG. SCI. 46:264–268, 2006. © 2006 Society of Plastics Engineers     

Natural Weathering Effects on the Mechanical,Rheological, and Morphological Properties of Magnetorheological Elastomer (MRE) in Tropical Climate

Magnetorheological elastomer (MRE) materials have the potential to be used in a wide range of applications that require long-term service in hostile environments. These widespread applications will result in the emergence of MRE-specific durability issues, where durability refers to performance under in-service environmental conditions. In response, the outdoor tropical climatic environment, combined with the effects of weathering, will be the primary focus of this paper, specifically the photodegradation of the MRE. In this study, MRE made of silicone rubber (SR) and 70 wt% micron-sized carbonyl iron particles (CIP) were prepared and subjected to mechanical and rheological testing to evaluate the effects under natural weathering. Magnetorheological elastomer samples were exposed to the natural weathering conditions of a tropical climate in Kuala Lumpur, Malaysia, for 30 days. To obtain a comprehensive view of MRE degradation during natural weathering, mechanical testing, rheology, and morphological evaluation were all performed. The mechanical and rheological properties test results revealed that after 30 days of exposure and known meteorological parameters, Young’s modulus and storage modulus increased, while elongation at break decreased. The degradation processes of MRE during weathering, which are responsible for their undesirable change, were given special attention. With the help of morphological evidence, the relationship between these phenomena and the viscoelastic properties of MRE was comprehensively defined and discussed.     

Preparation and properties of magnetorheological elastomers based on silicon rubber/polystyrene blend matrix

Magnetorheological (MR) elastomers, which are mainly composed of magnetic particles and elastic polymer, are a new kind of smart materials whose modulus can be controlled by changing the strength of magnetic fields. In this article, MR elastomers based on immiscible silicon rubber/polystyrene (SR/PS) blend matrix were fabricated successfully via cosolvent method and the MR effect, electric and mechanical properties, and the microstructures of the corresponding materials were studied. SEM studies showed that the dispersion of iron particles in blend matrix were different from that in single polymer, which could be further proved by the different electric conductivity. The MR effect of MR elastomers based on blend matrix varied with the different ratios of SR and PS, which was discussed in detail from the special dispersion of iron particles and of zero‐modulus of MR elastomers. In addition, the MR elastomers based on SR/PS blend matrix had enhanced mechanical properties, which made them more hopeful to be applied in practice. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3143–3149, 2007     

Influence of magnetic field upon the electric capacity of a flat capacitor having magnetorheological elastomer as a dielectric

The flat capacitor is built of two non-magnetic plates (with dimensions 0.065 m × 0.050 m) between which there is a layer of magnetorheological elastomer (MRE). The thickness of the layer is 0.0015 m ± 10%. MRE is based on silicone rubber and iron particles. The iron particles diameter ranges between 0.12 μm and 0.75 μm. The electric capacity, in absence of the magnetic field, is 377 ± 1 pF. In cross magnetic field with strengths up to 94 kA/m, the flat capacitor's capacity increases by up to 200%. For well chosen values of the intensity of the magnetic field, the capacity of the flat capacitor with MRE changes with time. The experimental results obtained in this manner are discussed.