Analysis of mechanical and dimensional properties of the denim fabrics produced with double-core and core-spun weft yarns with different weft densities

Elastic structures are preferred for improving the elasticity and recovery properties of denim fabrics. With the intention of improving comfort during body movements in denim jeans, 10–35% elasticity is required. In this study, the effect of the composition of double-core (dual-core) and core-spun weft yarns and weft density on the mechanical properties of denim fabrics was investigated. For this purpose, different core materials were used in the production of elastic yarns. The sheath material was cotton for all yarn types. Yarn samples were spun with the same yarn count and twist coefficient. 100% cotton Ne 8/1 Ring slub warp yarns were used as warp yarn while double-core and core-spun yarns were used as weft yarns in weaving. The weaving process was performed with three different weft density values (16, 22, and 28 weft /cm) and the other production parameters were kept constant. Twill 3/1 woven fabrics were treated according to standard denim finishing procedures. After domestic washing processes, mechanical properties of the samples were tested and statistically evaluated.     

Determinants of electrical resistance change of in situ PPy-polymerized stretch plain woven fabric under uniaxial tensile strain

Although the conductive stretchable woven fabric has been widely used as the sensitive material of strain sensors monitoring human motion, it is lack of a deep understanding of the determinants of its electrical resistance change under uniaxial tensile strain. This study chose two kinds of typical stretchable plain woven fabric, i.e. cotton/spandex core-spun yarn fabric and polyester/spandex filament yarn fabric, and they were coated by in situ polymerization of polypyrrole. Their electromechanical responses under certain uniaxial tensile loadings were measured and compared. Meanwhile, by a multi-architecture analysis, i.e. the intrinsic resistance of yarns, the contact resistance of interlacing yarns and the contact resistance of adjacent yarns in parallel, several hypotheses were proposed and tested to determine the determinants of electrical resistance change under tensile strains. The results showed that the resistance change in woven fabric with in situ polymerization of polypyrrole mainly depends on the contact resistance of the adjacent conductive yarns in tensile direction, and the electromechanical responses of the cotton/spandex core spun yarn are significantly different from those of the polyester/spandex filament yarn. It was concluded that the conductive yarn density and fabric structure are critical parameters of woven fabric as resistive strain sensor.     

Elastic Recovery and Performance of Denim Fabric Prepared by Cotton/Lycra Core Spun Yarns

ABSTRACT

Elastic performance coefficient (EPC) and recovery behavior of denim fabrics prepared with cotton/lycra core spun stretch yarns have been presented in this article. The denim fabrics are woven as broken twill weaves in an air-jet weaving machine by the insertion of core spun yarns (lycra filament in core, cotton fiber on sheath) as weft and using 100% cotton yarns as warp. The effect of linear density and stretch percentage of the core spun weft yarns on tensile and recovery behavior of denim fabric have been investigated by employing full factorial design of experiments. It has been observed that the tensile strength and EPC of fabric increase with decrease in linear density and stretch percentage of the core spun stretch yarn. The immediate elastic recovery and delayed elastic recovery increase with decrease in linear density and stretch percentage of the yarns.     

不锈钢纤维/涤纶特种花式线及其电磁波屏蔽织物的开发

以不锈钢长丝和有色涤纶丝等为芯纱原料,纯棉纱线及彩色涤纶丝为饰纱原料,在HKV151B型花式捻线机上纺制出具有电磁波屏蔽特殊功能的23种花色的花式线;用SL7900剑杆小样织机进行小样试织,设计织制了10个规格系列的电磁波屏蔽功能织物小样。电磁屏蔽性能和常规性能测试的结果显示,花式线织物具有突出的抗电磁屏蔽性能,并可满足常规家用休闲防护服面料的基本服用性能和外观风格要求。     

不锈钢纤维/棉复合纱的开发及其性能

为更好地开发和利用功能性纱线和面料,以不锈钢短纤维、不锈钢长丝以及棉纤维为原料,采用一种长丝/短纤维复合结构纱线的纺纱工艺开发出不同金属纤维含量的新型复合结构纱线。对复合结构纱线的结构,毛羽,拉伸性能以及导电性能进行测试分析。同时测试了利用该种复合结构纱线开发出的电磁屏蔽面料的屏蔽性能。实验结果表明：利用此种复合结构纱线制作方法所开发出的纱线具有较优异的毛羽性能、力学性能和导电性能,并且不锈钢纤维含量对纱线性能有着较大的影响。利用该种复合结构纱线开发出的面料屏蔽率达到90%-99.9%,可用于日常生活用电磁防护装材料。     

不锈钢短纤维/棉包覆氨纶纱的弹性与电学性能

为开发兼具弹性和导电性能的电磁功能纱线,以氨纶为芯丝、外包不锈钢短纤维/棉混纺纱,研制系列弹性不锈钢短纤维/棉包覆氨纶纱。在Instron 5566万能试验机上,结合万用表,获得弹性纱线的应力-应变、应变-电阻以及定伸长弹性回复曲线,研究纱线在不同拉伸状态下的电学性能。结果表明:不锈钢短纤维/棉包覆氨纶芯丝的纱线,存在氨纶芯丝的断裂现象,将不锈钢短纤维/棉包覆氨纶芯丝的纱线直接与氨纶丝或氨纶/棉包芯纱直接并合的方式,赋予纱线弹性;随着不锈钢短纤维含量的增加,弹性纱线的弹性伸长和回复性能都降低,塑性变形增加;随着弹性纱线应变的增加,其电阻先增加后降低。     

用Dref 3摩擦纺多组分纬纱织造的织物的风格特征

研究分析了3种用Dref3摩擦纺多组分纬纱织造的平纹织物的风格特征。3种不同的纬纱是：芯皮均为粘纤;水溶性PVA作皮,粘胶无捻纱条作芯;PVA无捻纱条作芯,粘纤作皮。3种纱均在Dref3型摩擦纺机上按芯皮50／50比例纺成,经纱统一采用2合股纯棉纱线。将3种纱分别织成织物,然后用热水将PVA溶解去除。织物性能的测定结果：织物性能与组成织物的纱组分性能并不一致。无捻芯纱(溶掉PVA表皮)织物具有较高的拉伸强力、撕裂强力、折皱回复性和耐磨性;而空心纱(溶掉PVA作芯)织物具有丰满、蓬松的结构和良好的耐压缩性能。     

Finite element analyses of stress distributions of three-dimensional angle-interlock woven composite subjected to three-point bending cyclic loading

This paper presents the finite element simulation of stress distribution features of 3D layer-to-layer angle-interlock woven composite undergoing three-point bending cyclic loading. With the finite element analysis model, a microstructure shell element model of the woven composite at yarn level was established to calculate the fatigue behaviors and stress distribution during cyclic loading. The stress distributions in the warp, weft yarns, and the resin regions have been calculated to show the stress difference in the woven composite. It has been observed that the warp yarns share the most part of the stress or loading, i.e. the strength warp yarn is more important than that of the weft yarn for the fatigue design. In addition, the stress distributions at the locations where the weft yarns crossover the warp yarns have been investigated. The stress degradations of the top and bottom surface of the woven composite panels were also compared with those in experimental and good agreement was found. With the stress distribution in the woven composite, the method of improving the fatigue damage tolerance was expected to be developed.     

三维正交机织复合材料的冲后压缩性能

为揭示纱线张力对三维机织复合材料抗冲击及冲后压缩性能的影响规律,基于多剑杆织造工艺,配置不同接结纱张力(25、50、100 cN)织造三维正交机织物,通过真空辅助树脂传递模塑成型工艺制备复合材料,并在室温下进行低速冲击及冲后压缩性能测试。结果表明：当接结纱张力为100 cN时,试样在冲击载荷下发生表层树脂大面积破裂和剥离并使纬纱失去支撑,同时,试样表层纬纱发生较大卷曲,促使压缩载荷发生屈曲失效;接结纱张力为100 cN试样的压缩性能相比接结纱张力为25 cN试样下降约50%;接结纱张力较高时易导致纬纱卷曲增大和树脂富集,并由此降低试样的弯曲刚度和冲后压缩性能。     

捻度对棉/氨纶/银丝包芯纱性能的影响

为了制备具有良好纺织特性的弹性导电纱线材料，以棉粗纱、氨纶、银丝为原料，通过设计原料的喂入方式及在环锭纺纱机的前罗拉与导纱钩之间附加定位装置，纺制以氨纶为纱芯、银丝与棉纤维螺旋包缠氨纶且棉纤维位于纱线表面的弹性导电包芯纱，探究捻度对纱线弹性、导电性、耐磨性和断裂强力的影响。以银丝紧贴氨纶表面包缠为模型，计算得到不同捻度下包芯纱中紧贴氨纶表面包缠的银丝长度的理论值。实验结果表明：包芯纱的弹性随捻度变化，在70捻/(10 cm)时包芯纱定伸长伸长弹性率、定负荷伸长弹性率较大；在包芯纱伸直(不伸长)状态下，纱线实测电阻值随捻度的增大而增大；在包芯纱伸长10%的状态下其实测电阻值小于伸直状态下等长度包芯纱实测电阻值，且在75捻/(10 cm)时伸长状态与伸直状态下的相同长度包芯纱的实测电阻值之差较小。     

Effect of cotton fiber and yarn characteristics on color variation in woven fabric dyed with vat dyes

The aim of this study was to investigate the effect of cotton fiber and yarn characteristics on the color variation of woven fabrics dyed with vat dyes. A fabric length of 31?m was woven so that each meter of the fabric comprised weft yarns of slightly different cotton fiber or yarn characteristics as compared to the other. The woven fabric was pretreated and dyed with vat dyes using industrial-scale, pad-dry-chemical-pad-steam process. After dyeing it was found that the fabric containing weft yarns made from cotton with higher reflectance (Rd) values gave poor color strength as compared to that of lower Rd values. Fabric comprising combed weft yarns showed better color depth (K/S) values as compared to that comprising carded weft yarns made from the same raw cotton. Furthermore, the fabric comprising finer- or lower-twist weft yarns gave higher color depth as compared to that with coarser or higher-twist weft yarns. It was concluded that slight variations in the cotton or yarn characteristics in the weft yarns could result in significant shade variations in the vat-dyed fabric.     

石墨烯黏胶纤维机织物的功能改性研究

制备同规格的普通黏胶纤维机织物、石墨烯黏胶纤维机织物及不同不锈钢丝质量分数的石墨烯黏胶纤维/不锈钢丝机织物,对比它们的导电、防电磁辐射、防紫外线、抗静电、力学(拉伸、弯曲、耐磨)及透气等性能。结果表明:普通黏胶纤维经石墨烯改进后,所制成的石墨烯黏胶纤维机织物的导电、防电磁辐射、防紫外线、抗静电、力学(拉伸、弯曲、耐磨)等性能都有所改善,其中防紫外线与耐磨性能提高显著,透气性能下降明显;石墨烯黏胶纤维/不锈钢丝机织物的导电、防电磁辐射、防紫外线和抗静电、经向拉伸断裂强力、纬向抗弯刚度、透气性能都优于石墨烯黏胶纤维机织物,纬向拉伸断裂强力、经纬向拉伸断裂伸长率、经向抗弯刚度及耐磨性能不及石墨烯黏胶纤维机织物;随着不锈钢丝质量分数在7.0%~20.0%范围内的增加,石墨烯黏胶纤维/不锈钢丝机织物的导电、防紫外线、抗静电、经向拉伸断裂强力、纬向抗弯刚度及透气性能增强,纬向拉伸断裂强力、经纬向拉伸断裂伸长率、经向抗弯刚度、耐磨性能减小,不锈钢丝质量分数变化对防电磁辐射性能影响较小。当不锈钢丝质量分数为7.0%时,石墨烯黏胶纤维/不锈钢丝机织物的综合性能最佳。     

抗静电增强芳砜纶面料的性能研究

将芳砜纶分别与有机导电丝和不锈钢丝进行赛络菲尔纺,制成股线并织造,对比分析有机导电丝和不锈钢丝对织物性能的影响.结果表明:加入导电长丝可明显减少纱线毛羽;加入导电长丝后,织物的电荷面密度降低,抗静电性增强;加入有机导电丝的织物撕破强力高于加入不锈钢丝的织物.     

Development and characterization of conductive ring spun hybrid yarns

Development of conductive yarns for smart textile applications is the most demanding area of research these days. This study was aimed to investigate the effect of yarn constructional parameters, and relative humidity on electromechanical properties of conductive ring spun hybrid yarns. Stainless steel (SS) fibre was blended with polyester and viscose fibre separately on 12% and 24% weight basis to produce hybrid conductive yarns at three different levels of twist factor. The electromechanical properties of yarns were evaluated in response to change in blend type, blend ratio, twist factor, and relative humidity. The content of SS fibre is found to be more effective followed by the twist factor and blend type to govern the linear electrical resistance (LER) of conductive yarns. In addition, on increasing relative humidity, the LER of viscose stainless steel (VS) hybrid yarns are found to drop significantly than that of polyester stainless steel (PS) hybrid yarns.     

有机导电短纤维混纺纱的导电和抗静电性能

为研究有机导电短纤维对面料抗静电性能的影响,用不同纺纱方法将不同比例的有机导电短纤维分别与涤纶和棉混纺,并对其面料的导电性能进行研究和评价。结果发现：在导电纤维含量相同的情况下,环锭纱的导电性能好于转杯纱;有机导电纤维的含量为4％左右时,面料的比表面积电阻降低到107~109 Ω/cm2之间,可以满足抗静电的要求,进一步提高含量不仅增加成本,而且对面料的服用性能会有影响,对抗静电性能没有实际意义;小比例有机导电纤维对混纺纱线的强力和断裂伸长等物理指标无明显影响。     

Warp and weft directional tensile properties of multistitched biaxial woven E-glass/polyester composites

The objective of this research work was to understand the warp and weft directional tensile properties of the two-dimensional multistitched multilayer E-glass/polyester woven composites. The warp and weft directional specific tensile strength and modulus of unstitched structure were higher than those of multistitched structures as stitching caused minor warp and weft yarn filament breakages. Contrarily, the specific tensile strains of unstitched structure were slightly lower than those of all multistitched structures. The stitching yarn type, the number of stitching directions, and the stitching density generally influenced the warp and weft directional tensile properties of multistitched E-glass/polyester woven composites. The failure of warp and weft directional multistitched woven E-glass/polyester composite structures was matrix breakages, and partial and complete yarn breakages in their surfaces. They had a local delamination in their cross-sections and the delamination did not propagate to the large areas due to multidirectional stitching. Also, the failure was confined at a narrow area and resulted in the catastrophic fiber breakages. The warp and weft directional specific damaged areas of multistitched structures, in particular four-directional stitching, were significantly lower than those of the unstitched structures. This indicated that the multistitching made the structures better damage-tolerance materials.     

含变异结构的三维机织复合材料的轴向拉伸性能

为克服加纱或减纱造成三维机织预制体交织结构的局部变异,进而对复合材料的力学性能产生一定的影响,采用加纱和减纱相结合的方法分别制备了4种三维机织石英纤维树脂基复合材料,结合拓扑方法建立了加减纱区域的路径,利用数字图像相关技术研究了拉伸过程中全场纵向应变变化。结果表明:引入加、减纱变异结构试样的拉伸强度和拉伸模量的保留率分别大于93.0%和88.0%,断裂伸长率无明显差异,且与未引入加、减纱试样在拉伸过程中的力学响应规律、断裂失效模式基本一致;应变云图表明损伤起始于交织点,引入加减纱的试样其高应变集中在加减纱“点”处,同时存在富树脂低应变区域与之对应。     

金属纱线排列方式对屏蔽效能的影响

为研究织物屏蔽效能的通用影响因素,采用金属纱线制备了不同排列结构下的模型样品,用屏蔽室法测试了1～18GHz内样品的屏蔽效能及反射系数。研究结果表明,采用屏蔽室法对样品测试时,由于电磁场的方向性,样品的放置方向对测试结果影响显著。金属纱线的排列间距是屏蔽效能的重要影响因素,屏蔽效能随着排列间距的增加而减小。同样排列间距下,不锈钢混纺纱样品的屏蔽效能和镀银纤维以及裸铜丝样品相近,高于不锈钢包芯纱和纯不锈钢长丝及其并捻纱样品。平行排列样品和网格排列样品的屏蔽效能一致。上述规律也适用于反射系数。     

采用现代工艺的传统风格夏布开发

为了减少传统夏布织造的人工投入、降低生产成本、缓解对传统手工艺人技术依赖程度,降低生产成本,提高质量,用环锭纺苎麻纱和剑杆织机进行传统风格夏布的制作。结果表明: 采用现代工艺,经纱选用普通的线密度为27.8tex的环锭纺苎麻纱,纬纱采用线密度为90.9tex的传统手工拈绩纱,用剑杆织机可织造出具有传统风格的夏布;现代工艺织造的夏布生产成本仅为传统生产工艺的三分之一,幅宽可以达到150cm,其幅宽与布面质量稳定、布边笔直、表面平整;对应用现代工艺织造的夏布风格和性能的测试结果显示,其外观风格、力学性能保留了传统夏布的特征。     

可加热纬编针织物的电热性能

为开发可加热纬编针织服装,采用衬纬方式将导电丝织入针织物中,并对其电热性能进行测试和分析。分别将单根、2根、3根镀银长丝和单根不锈钢长丝衬入到针织物中,测试导电纱线的最大负载电流、织物的热稳定性、织物的电热升温特性和表面温度的均匀性。结果显示:不锈钢长丝的最大负载电流最大,其次是3根镀银长丝的;通电后,衬入镀银长丝织物的电阻变化率较小;衬入3根镀银长丝的织物通电后温度升高的速度较快,且达到稳定工作的温度较高;测试范围内,织物的稳定温升与输入电压成正比;织物表面温度均匀性较好。认为可选择衬入3根镀银长丝的纬编织物制作可加热针织服装。