剪切增稠液/高性能纤维复合材料防刺性能的研究

制备出剪切增稠液体(STF),通过抽拔实验和红外测试从宏观与微观两个方面进行分析研究,"粒子簇"生成机理能较好地解释这种现象。并将该剪切增稠液对芳纶、超高分子量聚乙烯、S-玻璃纤维这三种用于防护材料的高性能纤维进行复合。通过对处理后的纤维复合材料进行扫描电镜和静态防刺实验,来分析这三种STF/纤维复合材料的微观形态及其防刺性能。研究结果表明,在纤维织物面密度相同的情况下,剪切增稠液体的使用能够有效增强这三种不同高性能纤维织物的防刺性能,使得其顶破强力分别比未处理的提高了16.13%、13.37%和16.47%。     

分散相和分散介质对剪切增稠胶动态力学性能影响研究

研究了分散相和分散介质对剪切增稠胶动态力学性能的影响,为制备性能较好的剪切增稠胶提供理论依据。测试分析了用不同粘度的二甲基硅油制备剪切增稠胶的动态力学性能,其中由粘度为500 cst的二甲基硅油制备的剪切增稠胶剪切增稠效应和阻尼性能较优。测试分析了不同质量分数纳米二氧化硅制备的剪切增稠胶动态力学性能,分散相质量分数在一定的范围内,剪切增稠胶的剪切增稠效应和阻尼性能随纳米二氧化硅质量分数的增加而提高;但是纳米二氧化硅质量分数高于一定范围时,纳米二氧化硅质量分数的提高对剪切增稠胶的剪切增稠效应和阻尼性能有负影响。     

剪切增稠液体在个体防护装甲上的应用进展

介绍了剪切增稠液体(STF)的特点及其在动态和稳态剪切应力下的流变行为;综述了STF在防弹和防刺装甲上提高防护性能的应用、作用机理以及STF-织物复合材料的制备方法;指出了STF在个体防护装甲应用中下一步的研究方向.     

剪切增稠液体的性能及其在柔性防刺材料中的应用

介绍了剪切增稠液体的特点、增稠机制及其流变性能的主要影响因素。在此基础上,又从机织物、针织物、非织造布角度列举并介绍了剪切增稠液体在柔性防刺材料中的研究现状,并对其在柔性防刺材料中的研究以及未来的发展做出了展望。     

高浓度球形二氧化硅粒子悬浮液流变行为研究

采用stober方法制备了单分散球形二氧化硅粒子,利用球磨分散技术制备了稳定的二氧化硅/聚乙二醇200体系,对该体系的稳态流变性能进行研究,考察了粒子浓度,粒径,温度对体系流变性能的影响。结果表明,当剪切速率小于临界剪切速率时,体系呈剪切变稀行为;当剪切速率大于临界剪切速率时,体系呈剪切增稠行为。随粒子的浓度增大体系在测试剪切速率范围内的粘度增大,临界剪切速率减小,剪切增稠幅度增大。     

纳米SiO_2对原位聚合法的硼酚醛树脂性能的影响

采用原位聚合法制备了硼酚醛树脂(BPR)/纳米SiO_2复合材料,考察了纳米SiO_2用量对复合材料力学和热学性能的影响。结果表明,适量纳米SiO_2的引入可显著改善复合材料的力学和热学性能。当纳米SiO_2质量分数为2%时,复合材料的冲击强度达到最大值13.5kJ/m~2;当纳米SiO_2质量分数为3%时,复合材料的拉伸强度达到最大值125.1 MPa,耐热性最好,玻璃化转变温度为107.6℃,700℃热残留率达到最高57.8%。     

浓度对超细钛白悬浮液结构及沉降性的影响

为探索浓度对超细钛白悬浮液结构及沉降性的影响,首先通过悬浮液流变实验研究固体浓度对钛白-水悬浮液流动性的影响,得到浓度与悬浮液表观粘度、剪切应力与剪切速率等的关系.然后通过悬浮液稳定性实验研究不同浓度下的悬浮液流体动力学特征.实验结果表明当浓度达到35%左右时,悬浮液开始出现网状结构,有较低的剪切屈服应力.浓度对悬浮液的结构影响很大,可分为单颗粒弥散型、单颗粒团型及网状结构等,不同结构其沉降机理也不同,分别对应的是单颗粒沉降、团聚体的干涉沉降和压缩沉降.     

剪切增稠液及其复合材料的研究进展

剪切增稠液（STF）作为新一代智能耗能材料广泛应用于抗刺扎、抗冲击和阻尼减振等领域。介绍STF的特性和剪切增稠机理,综述STF复合材料的制备方式,包括浸渍或喷涂、夹层或填充、共混以及胶囊化;分析STF复合材料的抗刺扎性能、抗冲击性能、阻尼减振性能与应用。建议进一步探索STF的剪切增稠机理,研发对环境不敏感、长使用寿命、可在高冲击速率下应用、磁流变性或电流变性的STF复合材料。     

羟基对高含量氧化硅分散体系流变性能的影响

通过红外光谱、光电子能谱和流变仪研究了氧化硅表面羟基对其高固含量悬浮液流变性能的影响。结果表明:氧化硅表面硅醇基在剪切增稠流体的形成中可能起着重要作用。在相同粒径和氧化硅的质量分数相同的情况下,氧化硅表面羟基的相对含量对其浓缩分散液有显著的影响,这种影响通过液体介质分子和逐渐增多的氧化硅表面硅醇基形成的多缔合氢键发生作用,不同羟基含量的氧化硅粒子制备的悬浮液流变性能有显著变化。     

剪切增稠液体增强纤维复合材料融合体育发展研究

剪切增稠液体是一种固液混合状态的胶体,介绍了剪切增稠液体及其增强纤维复合材料的制备工艺与流程,分析了剪切增稠液体增强纤维复合材料在体育领域的应用,旨在为体育产业应用先进材料提供借鉴。     

Rheological behavior of concentrated silica suspension and its application to soft armor

The objective of this study is to develop an advanced stab and/or ballistic proof material composed of shear thickening fluid (STF) and Kevlar composite fabric. In this study, we prepared STF using sphere silica and fumed silica as silica particles and ethylene glycol and polyethylene glycol (PEG 200) as medium fluid, respectively. And the rheological properties of the STF were investigated under different conditions. Also, we impregnated Kevlar fabrics with the STF, and investigated the stab and ballistic resistances of the targets layered by the STF impregnated Kevlar fabrics. From the results, we observed that the STF significantly showed the reversible liquid–solid transition at a certain shear rate, and the STF treatment significantly improved the stab and ballistic resistance of Kevlar fabric. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Application of shear thickening fluid in ultra high molecular weight polyethylene fabric

An advanced stab‐resistant material composed of shear thickening fluid (STF) and ultra high molecular weight polyethylene (UHMWPE) fabric was investigated. STF was prepared by dispersing nanosilica (SiO₂) into ethylene glycol. The shear thickening behavior of STF with the increase of the shear rate was observed by PhysicaMCR301. STF/UHMWPE composite fabric was synthesized by impregnating UHMWPE fabric in STF dilution. Stab resistant experiment was conducted on a self‐made stab test machine with knife and spike as stab tool. The results demonstrate that the stab resistant property of the UHMWPE fabric is greatly improved by impregnating STF. The stab resistant property is greatly increased with the increase of mass fraction of silica in STF. Especially, when the mass fraction of SiO₂ in STF is 38%, the stab resistance force and energy absorption of STF/UHMWPE are optimal for knife and spike threats. With the same stab resistant properties, the flexibility of UHMWPE fabric impregnated with STF is higher than that of the neat fabric. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Impact behavior of aminosilane functionalized nanosilica based shear thickening fluid impregnated Kevlar fabrics

In the present work, two types of shear thickening fluids have been synthesized by using neat and aminosilane functionalized silica nanoparticles and their viscosity curves have been obtained by the rheometer. Based on the values of peak viscosity of synthesized shear thickening fluids, the surface functionalized nanosilica based shear thickening fluid has been chosen as a best candidate due to the high viscosity for impregnation into the neat Kevlar of different layers viz. four (04) and eight (08) layers for velocity impact study. The experimental investigations reveal high energy absorption of shear thickening fluid impregnated Kevlar as compared to the neat Kevlar. The maximum energy absorption 62 J is achieved corresponding to the initial velocity 154 m∙s⁻¹ for 08 layers shear thickening fluid impregnated Kevlar specimen. The data have also been analytically determined and validated with the experimental data. The experimental data have good agreement with the analytical data within the accuracy of around 15 to 20%. The present findings can have significant inferences towards the fabrication of shear thickening fluids using nanomaterials for numerous applications such as soft armors, dampers, nanofinishing and so forth.     

Preparation of body armour material of Kevlar fabric treated with colloidal silica nanocomposite

Abstract

To safeguard bodies of soldiers better, including their necks and joints, a novel armour material was exploited using nanocomposite. Compared with traditional armour materials, this new material possessed superior barrier property and more comfortable characteristics. The new armour material was made of Kevlar cloth and shear thickening fluid (STF). Colloidal silica particles were first synthesised via the Stöber synthesis method and then they were used to prepare a suspension with solvent of polyethylene glycol 200. At last, Kevlar cloth was treated with the suspension and the resultant was named as STF–Kevlar nanocomposite. In this process, the particle sizes were characterised with scanning electron microscopy. The rheological properties were measured with a Physica MCR301 stress controlled rheometer. The results showed that the silica particles could be determined to be monodispersed spherical particles. The suspension, named the shear thickening fluid, had shear thickening characteristic. The property of multilayer STF–Kevlar nanocomposite targets was compared to that of the neat Kevlar cloth and the results indicated that the STF–Kevlar nanocomposite had an improvement in barrier property and was more flexible and comfortable. The mechanism that could improve the barrier property of STF–Kevlar was briefly explained.     

Studying the mechanical properties of composites made of Kenaf‐Nylon 66 fabric,silica nanoparticles,and epoxy resin

In this study, the effect of the relationship between yarn material and yarn count tex on the mechanical behavior of plainly woven hybrid fabrics impregnated with silica nanoparticles and epoxy resin has been investigated. First, various types of bicomponent and single‐component fabrics with plain weaves are prepared using kenaf and nylon‐66 yarns with yarn tex count of 334 and 427. To prepare the composite, silica nanoparticles with a particle size of 200 nm are mechanically mixed into glycol polyethylene with a molecular weight of 200 along with ethanol in proportions of 6:1. The weight percent of silica particles in the suspension has been selected as 60%. Using a round edge indenter, the concentrated indentation force test has been performed based on the 6264D standard to determine the strength of each fabric sample. Then, by impregnating the mentioned fabrics with polymer materials (silica nanoparticles and epoxy resin) and performing the concentrated force tests again, it is found that the hybrid fabrics with a yarn tex count of 427 and impregnated with polymer material enjoy the highest shear thickening properties. POLYM. COMPOS., 37:674–683, 2016. © 2014 Society of Plastics Engineers     

Effects of silica morphology on the shear-thickening behavior of shear thickening fluids and stabbing resistance of fabric composites

Shear-thickening fluid (STF) refers to a system where nonaggregating solid particles are suspended in a specific fluid. Due to its unique viscosity variation, STFs have attracted a lot of attention as soft body armor materials for impact protection. In this work, two kinds of STFs were designed using polyethylene glycol (PEG) and spherical or irregularly shaped silica particles. Rheological results showed that shear thickening can even occur at lower shear rates in the irregularly shaped silica-based STF; however, the thickening range of the spherical silica-based STF was broader. Meanwhile, the composites prepared with STFs and aramid fabrics exhibited better antistab properties than neat fabrics. Compared to composite prepared with irregularly shaped silica-based STF, spherical silica-based STF/aramid composite had better stabbing resistance. In addition to the binding effect of silica particles to the fiber bundle, it was considered that when the fabric composite was subjected to impact, spherical particles were easier to slide so that the STF was more likely to be thickened to achieve a greater viscosity, resulting in the better stabbing resistance performance. Our studies will provide guidance for the design of the high-performance soft body armor equipment. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48809.     

Stab resisting behavior of polymeric resin reinforced p‐aramid fabrics

The stab resistant performance of p‐aramid fabrics reinforced with thermoplastic LDPE resin and thermoset epoxy resin was investigated by quasi‐static or drop tower stab resistance testing, and the stab resistance behavior against different shapes of impactors was also evaluated. The destruction behavior of LDPE reinforced p‐aramid fabrics against a knife impactor shows three distinctive steps; the initial penetration step with maximum strength, the cutting step by knife edge, and the destruction step of accumulated fiber bundles. On the other hand, epoxy resin reinforced p‐aramid fabrics against a knife impactor exhibit just two steps without the accumulation of fiber bundles. In the case of a spike impactor, the maximum stab resistant strength is observed from the initial penetration step; however, the stab resistant strength after initial penetration drastically decreased regardless of the reinforcing resins. It is also found that, even if the LDPE reinforced fabrics are multilayered, the performance improvement by resin reinforcement is observed only from the initial penetration step and the stab resistant strengths of the cutting step and the fiber accumulation step are not improved. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

絮凝氧化铁悬浮液流变性质研究

应用LVDV-Ⅲ+型可编程流变仪测定了微米级氧化铁悬浮液絮凝处理后的流变特性,考察因素包括悬浮液固相质量浓度、pH值、絮凝剂添加量、搅拌速度。结果表明,悬浮液浓度不同,其流变性能也表现出不同,在相同剪切速率下,高质量分数悬浮液的表观粘度和剪切应力都大于低质量分数悬浮液的表观粘度和剪切应力;pH对絮凝悬浮液流变性有重要的影响。絮凝悬浮液粘度随pH的增加先增大后减小,絮凝剂聚合氯化铝添加量为80 mg的条件下,pH=6.14时表观粘度最大;絮凝剂浓度的不同,对于悬浮液流变性能的影响也不同,在相同剪切速率下,添加高浓度絮凝剂悬浮液的表观粘度和剪切应力都大于添加低浓度絮凝剂悬浮液的表观粘度和剪切应力,增加絮凝剂浓度对提高悬浮液粘着性能具有积极意义;对悬浮液搅拌强度不同其流变性能也表现出不同,在相同剪切速率下,悬浮液的表观粘度和剪切应力随着测试前对它搅拌强度的增加表现出先增大后减小。     

Preparation of alumina by aqueous gelcasting

The alumina ceramic was prepared by aqueous gelcasting. The effects of zeta potentials, solid loading, dispersant content and milling time on the alumina suspension were studied systematically. The dispersant content has remarkable effects on the viscosity of the suspension. The appropriate dispersant concentration for alumina aqueous slurry with the solid loading of 55 vol.% is 0.6 wt.%. It can be seen that all suspensions (50–56 vol.% solid loading) exhibited a shear-thinning behavior and relatively low viscosity, which was suitable for casting. The degree of shear thinning and the viscosity at high shear rates increased with increasing volume fraction of solid. As the milling time prolongs, viscosity of the suspension decreases first, then the plateau appears and the average diameter keeps changeless. When the milling time was shorter than 20 h, the viscosity of slurries decreased gradually as the time of milling increased. After 20 h milling, the viscosity of the slurry tended to be consistent. Therefore, the ball milling time should be equal to or more than 20 h to obtain a stable suspension at equilibrium. The time available for casting the slurry (idle time) can be controlled by the amounts of initiator and catalyst added to the slurry as well as by the processing temperature. Micrograph of the gelcast green body was homogeneous.     

Coal–oil–water multiphase fuel: Rheological behavior and prediction of optimum particle size

As the coal–oil–water slurry is gaining importance in place of fuel oil, a better understanding of handling characteristics is in demand. Therefore, experimental investigations have been carried out to investigate the rheological properties of coal–oil–water suspension containing coal particles of different sizes. Different coal stocks with average particle sizes of 108 μm, 75.7 μm and 62.9 μm have been used. The concentration of solid for the experiment varies from 10% to 50% by weight. All experiments have been carried out in a cup and bob type coaxial cylindrical viscometer. Newtonian, shear thinning and shear thickening behavior of suspension has been observed depending on component content and operating conditions. Study with different particle sizes shows that it is possible to achieve an optimum particle size for better handling of such suspension. A generalized correlation has been developed to predict the apparent viscosity of coal–oil–water suspension incorporating the coal concentration, oil concentration, torque and particle diameter. The experimental data are in well agreement with proposed correlation.