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%。     

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.     

体育击剑防护织物的制备及其防刺性能分析

采用经过碳纳米管改性处理的剪切增稠液对Kevlar织物实施剪切增强处理,进而制备出剪切增强复合Kevlar织物,并使用多功能电子织物强力仪对其防刺性能进行测试。经实验研究发现,本次研究所提出的Kevlar织物增强方案能够显著提升整体材料的动态刀刺力,延长防刺冲击时间。     

单分散氧化硅浓缩悬浮液浸渍Kevlar复合材料的防刺性能

以St(O)ber和离心交换法制备了不同浓度的单分散SiO_2/PEG浓缩悬浮液,并研究了其流变性能和用其浸渍Kevlar编织布所得复合材料的防刺性能.研究发现,所制备浓缩悬浮液在质量浓度低于50%时,具有微弱的剪切增稠效应,增稠所能达到的粘度值随浓度增加缓慢升高,而临界剪切速率降低;当浓度在55%左右时,先是剪切增稠,随后出现轻微的剪切减稀现象;当浓度达到65%时,出现较为显著的剪切增稠效应.所制备复合材料的防刺性能比纯Kevlar编织布有一定的提高,当SiO_2质量百分比浓度在40%～45%区间时,抗刺力可提高到1.66倍左右.     

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.     

剪切增稠液体材料的研究现状及其在人体防护装备上的应用

总结了国内外剪切增稠液体材料的研究现状,从其流变特性、增稠机理及其应用于人体防护装备的发展等方面进行了综述。阐述了影响剪切增稠液体材料流变性能的一些因素的研究现状,包括分散相粒子的性质、分散介质的性质、亲水长链高分子的添加量和温度等。     

SiO_2/PEG分散体系的流变学性能研究

随着剪切增稠液体在防护领域的应用,其流变学性能的研究显得尤为重要。本实验制备了一系列SiO2/PEG分散体系,并解释了制备过程中所出现的实验现象;采用高压毛细管流变仪测试了SiO2/PEG分散体系的流变性能。研究结果表明,随着剪切速率的变化,分散体系的表观粘度先减小后增大,并且剪切增稠现象具有可逆性;分散介质相对分子量的增大,不利于分散体系的剪切增稠;SiO2固含量越大,剪切增稠现象越明显。     

STF复合高分子纤维材料传统体育防护用具开发研究

文章介绍了剪切增稠流体（STF）复合高分子纤维材料的特性和分类,分析了不同体系STF材料的剪切增稠机理,然后探究了在体育防护用具的开发中STF复合高分子纤维材料的应用优势,最后研究了该复合材料在具体的防护装备和防护外衣中的开发与应用。     

剪切增稠液体的制备及其性能和应用

综述了以纳米二氧化硅/聚乙二醇(SiO2/PEG)分散体系为代表的剪切增稠液体的制备及其表征和应用情况。表明这些体系在低剪切速率下出现剪切变稀现象,而在高剪切速率下会出现剪切增稠现象,适用于防弹、减震等应用方面材料,特别在个体防护方面有很重要的应用。指出剪切增稠液体与芳纶织物复合的防弹材料在保持穿着舒适性和灵活性的前提下,比纯芳纶织物有更好的防护效果。此外还有纳米碳酸钙/聚乙二醇(CaCO3/PEG)分散体系等也是剪切增稠液体。     

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。     

高强织物防穿刺作用特征与机制分析

高强织物广泛应用于防刺领域。为了研究高强织物防穿刺作用特征与机制,自行设计了可调重量与高度的自由落体式实验装置,选用单刃刀、三棱刀、锥对芳纶与超高分子量聚乙烯纤维织物进行刺入实验,考察了冲击能量、刀具截面形状、刺入角度对穿刺作用的影响,研究了织物纤维种类、结构、叠层密度与织物防穿刺作用的关系,分析了刀具对高强织物穿刺作用的机制。结果表明,穿刺效果主要由能量的大小决定,受其速度、质量的组成比例影响较小;刀具的截面形状决定其穿刺织物时的剪切破坏与排挤破坏的组成形式;防刺材料的结构是影响其防穿刺性能的关键因素,同种材料不同结构织物抗排挤能力越强。织物对锥和单刃刀的防穿刺能力越强。对三棱刀的防穿刺能力变化不明显。     

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.     

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     

The rheological properties of shear thickening fluid reinforced with ZnO of different friction characteristics

The viscosity of shear thickening fluid (STF) changes significantly with low concentrations of additives. However, existing research has suggested that there has not been any consistent enhancement mechanism of additives. The possible reason for this research gap is that existing research has focused on the effect of the shape and content of additives on shear thickening (ST) performance, whereas the friction characteristics of additives on ST performance have not been considered. Accordingly, nanoparticle-enhanced STF with various friction characteristics of ZnO was synthesized in this study to investigate the enhancement mechanism of additives. The aspect ratio of ZnO with different shapes was obtained through SEM analysis. The friction characteristics of ZnO were examined. Lastly, the rheological behavior of reinforced STFs was evaluated. The results indicated that ST performance was enhanced compared with that of neat STF, which was significantly dependent on the friction characteristics of ZnO.     

不同体系剪切增稠液体的流变行为研究

剪切增稠液体是指其表观粘度随剪切速率增加而变大的一类流体。工业生产中,剪切增稠的出现会阻碍输送管道,破坏生产设备。针对这种情况,人们对如何降低流体粘度造成的不利影响进行了大量研究。另一方面,剪切增稠液体是“液体防弹材料”的关键组成部分,并且在减震、控制方面也具有可观的应用潜力。该文采用原生粒径为50 nm 的SiO2和80～100 nm 的 CaCO3分别作为分散相,聚乙二醇（PEG）200为分散介质,采用超声分散法制备得到不同固含量的剪切增稠液。并通过纳米粒度仪和扫描电镜对分散相粒子团聚情况进行分析;通过应力控制流变仪分别对 SiO2/PEG200和 CaCO3/PEG200悬浮分散体系的稳态流变性能进行分析。结果表明,两种体系试样在测试中均出现剪切增稠现象,并且分散相质量分数越高,剪切增稠效果越明显;而高质量分数的 SiO2/PEG200体系的粘度变化范围更大,增稠现象更为明显。     

Influence of carrier fluid on the electrokinetic and rheological properties of shear thickening fluids

This paper presents a study on the influence of hydroxyl groups and oxygen atoms together with chain length and branching of carrier fluid on the rheological and electrokinetic properties of shear thickening fluid (STF). An STF is non-Newtonian fluid behaviour in which the increase of viscosity increases with the applied shear rate. Ethylene glycol, triethylene glycol, 1,3-propanediol, glycerin, poly(propylene glycol) of different molecular weight and poly(propylene glycol) triol were used as the carrier fluids (dispersants). Silica powder with an average particle size of 100 nm was used as the solid phase. Zeta potential, particle size distribution (by DLS technique), steady-state and dynamic rheological measurements were conducted. Experimental results indicate that a different amount of hydroxyl groups and oxygen atoms together with chain length and branching of carrier fluids have a significant influence on the intermolecular interactions thereby and on the rheological properties of suspensions. Depending on the composition, it is possible to control rheological properties. The use of a suitable carrier fluid allows the required pattern flow to be obtained, from Newtonian through shear thinning to shear thickening, given specific shear conditions.     

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     

The effect of shear‐thickening on the stability of slot‐die coating

Slot‐die coating is an economical roll‐to‐roll processing technique with potential to revolutionize the fabrication of nano‐patterned thin films at high throughput. In this study, the impact of shear‐thickening of the coating fluid on the stability of slot‐die coating was investigated. For the coating fluid, a model system fumed silica nanoparticles dispersed in polypropylene glycol was chosen. These dispersions exhibit shear and extensional thickening characterized through steady shear and capillary break‐up measurements. The critical web velocity for the onset of coating defect for different flow rates was measured, while the type of coating defect was visualized using a high speed camera. For the shear thickening particle dispersions, the coating failed through the onset of a ribbing instability. The critical web velocity for the onset of coating defect was found to decrease with increasing particle concentration and increasing fluid viscosity. The minimum wet thickness was studied as a function of capillary number for the particle dispersions and compared with a series of Newtonian fluids with similar viscosities. In all cases, shear‐thickening behavior was found to stabilize coating by reducing the minimum wet coating thickness when compared against a Newtonian fluid with similar viscosity at the same capillary number. Conversely, the shear‐thinning fluids tested destabilized the coating by increasing the minimum wet thickness when compared against a Newtonian at the same capillary number. The impact of shear‐thickening on slot‐die coating was further studied by quantifying the evolution of the ribbing instability with increasing web speed and by conducting tests over a wide range of coating gaps. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4536–4547, 2016