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。     

NR/SBR并用橡胶基磁敏橡胶的制备及性能的研究

通过湿法预处理,用偶联剂KH-570对羰基铁粉进行表面改性,制备了综合性能较好的并用橡胶基实用型磁敏橡胶,研究了羰基铁粉含量对天然橡胶/丁苯橡胶(NR/SBR)并用橡胶基磁敏橡胶性能的影响;同时利用扫描电镜研究了改性羰基铁粉表面和磁敏橡胶复合材料断面的微观结构。结果表明,通过偶联剂改性的羰基铁粉其晶体结构未发生变化,且表面有一层致密的包覆层;以NR/SBR并用橡胶为基体的磁敏橡胶,当羰基铁粉用量为300份时,可表现出较好的机械性能和磁流变效应。     

Quadrupolar magnetoresistor based on electroconductive magnetorheological elastomer

The quadrupolar magnetoresistor presented in this paper is based on the electroconductive magnetorheological elastomer (MRE) such as discussed in this paper. It is shown that the electric resistances on each pair of terminals of the magnetoresistor can be controlled by an external magnetic field. The results obtained are able to serve for several applications.     

Dynamic properties of magnetorheological elastomers based on iron sand and natural rubber

In this study, magnetorheological elastomers (MREs) based on iron sand and natural rubber were prepared. The Taguchi method was employed to investigate the effect of a number of factors, namely, the iron sand content, iron sand particle size, and applied magnetic field during curing on the loss tangent (tan δ) and energy dissipated during cyclic loading. Tan δ was measured through dynamic mechanical analysis over a range of frequency (0.01–130 Hz), strain amplitude (0.1–4.5%), and temperature (?100 to 50°C). The energy dissipated was measured with a universal tester under cyclic tensile loading. The data were then statistically analyzed to predict the optimal combination of factors, and finally, experiments were conducted for verification. It was found that the iron sand content had the greatest influence on tan δ when measured over a range of frequency, and the energy dissipated during hysteresis tests. However, none of the factors showed a significant influence on tan δ when measured over a range of strain amplitude. Furthermore, the iron sand content and magnetic field were also found to influence the width of the peak in tan δ as a function of the temperature. The morphological characteristics of the MREs were also examined with scanning electron microscopy. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41506.     

Magneto-piezoresistive characteristics of graphene/room temperature vulcanized silicon rubber-silicon rubber magnetorheological elastomer

The effect of graphene with different content on the magneto-piezoresistive characteristics of graphene/room temperature vulcanized silicon rubber (GR/RTV) magnetorheological elastomer (MRE) was studied, and the relationship between the content of graphene and conductivity of GR/RTV-MRE was described based on the general effective medium theory. A magneto-piezoresistive model was established to describe the relationship among resistance, pressure, and magnetic field based on the magnetic dipole and tunneling theory. The samples of GR/RTV-MRE with different content of graphene were prepared. The experimental platform with magneto-piezoresistive characteristics controlled by magnetic field was built. The effect of graphene with different content on piezoresistive coefficient of GR/RTV-MRE was obtained under different magnetic flux density. The experimental results showed that the piezoresistive coefficients of samples with different content of graphene decrease with the increase of magnetic flux density in the range of 0 ~ 80mT. For the same magnetic field, when the volume fraction of graphene is less than 12%, the piezoresistive coefficient is positively correlated with it, when the volume fraction of graphene is more than 12%; the increase of content has little effect on the piezoresistive characteristics. The experimental results are compared with theoretical calculations for correction and error analysis. The results showed that the modified model can well describe the variation of the resistance of GR/RTV-MRE under magnetic field and pressure.     

Facial fabrication of self-healing natural rubber foam based on zinc thiolate ionic networks

In this work, self-healing natural rubber (SHNR) foam incorporating an intrinsic zinc thiolate ionic network was successfully prepared. The materials exhibited the ability to autonomously repair damage at room temperature without the need for external triggers. The investigation focused on the effect of sodium bicarbonate, employed as a blowing agent, on the self-healing performance, as well as the physical and mechanical properties of the foam. Various concentrations of sodium bicarbonate (0, 1, 4, 8, and 10 phr) were employed. The conventional two-roller mill was used for mixing and compounding, while compression molding was utilized for the vulcanization process. With increasing sodium bicarbonate concentration, the density, tensile strength, elongation at break, and compression set of the self-healing NR foam were found to decreased. Conversely, the porosity, shrinkage, compressive strength, and water uptake of the SHNR foam increased as the concentration of sodium bicarbonate increased. Scanning electron microscopy analysis revealed that the optimal concentration of sodium bicarbonate (8 phr) resulted in smaller, finer, and more uniform porous structures. The self-healing rubber foam incorporating 8 phr sodium bicarbonate exhibited improved properties in terms of tensile modulus, elongation at break, and tear strength, with healing efficiencies of 91.27%, 69.39%, and 83.99%, respectively.     

硅橡胶基尼龙帘线增强型磁敏橡胶的研究

磁敏橡胶是一种其力学、电学、磁学等性能可由外加磁场控制的新型智能材料,但因其机械力学性能问题限制了其实用化,而尼龙帘线因其具有强度高、模量高、尺寸稳定性和耐疲劳性能好等优点而成为橡胶制品用的理想骨架材料之一。本文首次试探性地制备了无磁场条件下的硅橡胶基尼龙帘线增强型磁敏橡胶,研究了尼龙帘线对硅橡胶基磁敏橡胶机械力学性能和磁流变性能的影响。结果表明,当硅橡胶基体中加入尼龙帘线时,可以极大地提高磁敏橡胶的剪切储能模量和拉伸强度,分别达到了0.415 MPa和9.21 MPa,同时也不影响材料的磁流变性能。     

Preparation of bio-based high-strength elastomer through in-situ generated ionic network based on itaconic acid in natural rubber

采用原位共混法使可再生的生物基材料衣康酸与氧化锌在天然橡胶（NR）中原位生成衣康酸锌,然后通过过氧化二异丙苯引发衣康酸锌接枝到NR分子链上,构筑羧酸锌离子网络。结果表明,该离子网络的可逆性能可有效提高NR的强度,无炭黑填充NR的拉伸强度达到16.7 MPa,扯断伸长率达472%,储能模量和损耗模量均增大。     

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%。     

纳米SiO2对天然橡胶/聚丙烯共混型热塑性弹性体的改性

在双辊电热式塑炼机上采用动态硫化法制备了天然橡胶/聚丙烯共混型热塑性弹性体(NR/PP TPV)。考察了纳米S iO2的加入顺序及其用量对NR/PP TPV力学性能的影响,研究了纳米S iO2填充改性TPV的耐溶剂性能和耐热变形性能,并用扫描电镜(SEM)观察了其两相结构和断面形貌。结果表明,纳米S iO2先与NR混炼均匀,再加入小料和硫黄所得的NR母炼胶与PP制备的TPV力学性能较好,且最佳的纳米S iO2加入量为3份;纳米S iO2改性的NR/PP TPV具有良好的耐溶剂性能和耐热变形性能;纳米S iO2提高了NR与PP相间结合强度。     

Slow-release fertilisers based on natural rubber

It is estimated that only between 30-70% of the fertiliser applied in agriculture is used for plant nutrition, the rest is carried away by ground water or lost through nitrification-denitrification. Apart from the economic loss due to wastage, severe environmental problems arise due to increasing nitrate concentrations in public drinking water. The research reports a method of binding the fertiliser urea into natural rubber thus forming a matrix of rubber encapsulated fertiliser. A special ‘split-feeding’ mixing technique is necessary for a good product; also found important were mixing and vulcanisation temperatures with the optimum being in the 70?82°C range and 95°C respectively.     

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。     

基于离子超分子网络实现自修复天然橡胶的制备

将甲基丙烯酸锌（ZDMA）或聚（甲基丙烯酸锌）低聚物（PM）引入到天然橡胶中,同时并用炭黑/白炭黑与天然橡胶共混,制备一种具有自修复性能的耐屈挠疲劳橡胶。研究结果表明,与PM相比,ZDMA可形成以离子交联为主的可逆超分子网络,赋予了硫化胶更好的自修复功能,当其用量为40份（质量）时硫化胶的自修复效率最高,接近100%。不饱和羧酸盐（ZDMA或PM）与传统填料（炭黑和白炭黑）并用时,PM仅在前期可有效抑制裂纹的扩展,ZDMA可明显提高材料的耐屈挠疲劳性能,当m（ZDMA）/m（炭黑）为20/40时硫化胶的耐屈挠疲劳性能最好。     

Ionic elastomer based on carboxylated nitrile rubber: infrared spectral analysis

Carboxylated nitrile rubber (XNBR) neutralized by metal oxide forms an ionic elastomer (ionomer) due to formation of ionic clusters by the metal carboxylated salt. Cluster formation in carboxylated nitrile rubber by metal oxide, mainly zinc oxide (ZnO), has been studied by infrared analyses. Two modes of plasticization, ie plasticization of the hydrocarbon‐rich phase and plasicization of the ionic domains (hard phase), have also been analysed by infrared studies. Results reveal that the cluster formation is stabilized at higher loading of metal oxide with hexacoordinate salt formation and depends on the type of metal oxide. Spectral studies also reveal that a non‐polar plasticizer such as dioctyl phthalate does not affect the characteristic bands of ionic cluster, but polar plasticizers such as dimethylsulfoxide and ammonia solvate the ionic cluster, causing the disappearance of the band corresponding to the hexacoordinated carboxylate salt. Infrared spectral analysis of the ionomer based on carboxylated nitrile rubber (XNBR) further confirms the earlier claims that the profound change in physical properties of the polymer is due to the presence of physical crosslinks generated by ionic clusters. © 2000 Society of Chemical Industry     

Effect of blending thermoplastic elastomer with natural rubber compound and studies of short fiber reinforced rubber composite

Rubber engineers face difficulties in scorching and vulcanizing during rubber processing, particularly of natural rubber (NR). Therefore, this work tried to solve these problems by blending thermoplastic rubber with NR compound. The results indicated that the scorch resistance of the NR was improved by blending the thermoplastic elastomer styrene–ethylene/butylene–styrene (SEBS). However, its mechanical properties were not found to be improved. Therefore, this study was extended to understand the reinforcement effects of short fiber carbon and glass fibers, on the mechanical properties of the thermoplastic elastomer with NR compounds. © 1996 John Wiley & Sons, Inc.     

A high toughness elastomer based on natural Eucommia ulmoides gum

Eucommia ulmoides gum (EUG) is a kind of bio-based polymer with similar structure to natural rubber (NR). However, it behaves as hard plastic at room temperature due to crystallization, which makes it not as widely used as NR. Herein, a new bio-based elastomer (HEUG) was prepared by rhodium-catalyzed hydrogenation of EUG for the first time. ¹H-NMR and ¹³C-NMR spectroscopy confirmed the structure of HEUG, and wide angle X-ray diffraction, polarizing light microscopy showed that the crystal was gradually destroyed in the hydrogenation process, finding that when the degree of hydrogenation is more than 16.5%, HEUG transformed from plastic to elastomer at room temperature. Besides, the Synchrotron Radiation experiment showed that HEUG with hydrogenation of 85.9% could be self-reinforced by strain-induced crystallization during stretching, which make it has excellent tensile strength and toughness (21.4 MPa and 68.1 MJ m⁻³, respectively). This new bio-based elastomer has the potential to replace NR and has a wide application prospect in rubber industry.     

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     

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     

Effect of molecular weight of epoxidized natural rubber on shear strength of adhesives

The dependence of shear strength of epoxidized natural rubber (ENR)‐based adhesives on molecular weight of the rubber is studied using coumarone–indene resin, gum rosin, and petro resin as tackifiers. The adhesive was coated on polyethylene terephthalate (PET) film substrate using a SHEEN hand coater at various coating thickness. The shear strength of adhesives was determined by a Texture Analyzer. Results show a maximum at 6.63 × 10⁴ and 4.14 × 10⁴ for ENR 25 and ENR 50, respectively, after which the shear strength decreases with further increases in molecular weight for all the coating thickness. This observation is attributed to varying degree of cohesiveness which culminates at the respective optimum molecular weight of ENR. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009