Fabrication And Performances Of Stretchable Metal Wire/Cotton/Spandex Wrapped Yarns

Elastic yarns containing metal wire can be widely used in numerous applications such as smart wearable electronics,flexible actuators,healthcare and military-civilian use,etc.However,traditional metal wirecontaining yarns usually suffer from common issues such as low elasticity,restricted strain,and poor skin comfort,failing to meet the demands of future wearable textiles in terms of mechanical flexibility and tactile comfort.The solution lies in developing spinning technologies that allow for easy control and processing into metal wire-containing yarn structures with superior elasticity.As a result,the main purposes of this research are to innovatively prepare stretchable wrapped yarns containing metal wire on a hollow-spindle spinning system,and then systematically focus on the structure and properties particularly pay attention to performance stability under complex conditions.In addition,a woven fabric capable of both excellent stretchability and electromagnetic shielding performances was fabricated,which can expand the application scope in personal protection fields.The main research extents are as follows:(1)Fabrication and the optimization of key processing parameters of stretchable metal wire/cotton/spandex wrapped yarns.First,based on a hollow-spindle wrap spinning frame,stretchable and conductive wrapped yarns were produced with spandex filament as the core,stainless steel wire and pure cotton yarn as the first-wrapped and second-wrapped components,respectively.The effects of some key spinning processing parameters such as wrapping twist,the draft ratio of spandex filament,and the inner-outer twist ratio on yarn properties such as tensile and elastic behaviors were investigated.Furthermore,the principal component analysis method is utilized to determine and optimize the key process parameters.The results reveal that the variables such as wrapping twist,the draft ratio of spandex filament,and the inner-outer twist ratio have certain impact on the tensile strength,extension at break and elastic recovery ratio of the resultant yarns.Finally,the optimized comprehensive performance parameters for the wrapped yarns were determined based on principal component analysis method namely,wrapping twist of 800 T/m,inner-outer twist ratio of100 %,and the draft ratio of spandex filament of 2.5.(2)Mechanical and conductive behaviors of wrapped yarns under complex events.Fabrics are usually accompanied by complex conditions such as high temperatures,high relative humidity during forming process or the subsequent use.Since textile yarns are the basic units of fabrics,to evaluate the service behavior of textile yarns under complex conditions is a necessary prerequisite.To this end,the wrapped yarns prepared using the optimized spinning parameters were treated with dry heating,wet heating and ultrasonic,and the indexes such as tensile,elastic behavior and electroconductive behaviors.The results indicate that the mechanical properties of wrapped yarns maintain constant following dry heating below 120 °C,wet heat and ultrasonic vibration,which means that the resultant properties is comparable to those of untreated(pristine)yarns.However,the tensile strength remarkably decreases when dry heating temperature exceeds120 °C,especially up to 180 °C.For example,the tensile strength decreases from the initial 1053.3 c N to 485.6 c N,and the elastic recovery ratio decrease from the initial 195 % to 90.8 %.with respect to the electrical conductivity,the resistance of wrapped yarns containing metal wire is mainly affected by the tensile strain applied,and the resistance fluctuates when stretched to about 200 %.Among these methods,high dry heat has a significant impact on the change in yarn resistance.The resistance of yarns maintain stability relatively under other events.(3)Fabrication and characterization of stretchable electromagnetic shielding woven fabric.Herein,a stretch woven fabric with 2/2 twill weave was made,and the warp and weft yarns of the woven fabric are pure cotton yarn and the optimized wrapped yarn,respectively.The electromagnetic shielding effectiveness of the above fabric was measured under different events such as weft extension,lamination.Furthermore,the underlying shielding mechanism was unraveled.The experimental results indicate that the placement direction of the fabric sample has a significant impact on the results due to the directional nature of electromagnetic field.The average electromagnetic shielding effectiveness of the fabric in the 8.2～12.4 GHz frequency band is approximately 21 d B,which is mainly achieved by reflecting electromagnetic waves for effective electromagnetic shielding.Furthermore,the tensile extension of the fabric is a vital factor influencing the shielding capability,and the electromagnetic shielding effectiveness increases with an increase of weft tensile extension.For example,the value of electromagnetic shielding increase to 35.9 d B at a high tensile extension of 40 %.Increasing the number of fabric layers enhances electromagnetic shielding effectiveness remarkably.For example,when layers of fabric are placed parallel to each other,the maximum shielding effectiveness of 38.6d B,while when they are crossed,the maximum shielding effectiveness of34.6 d B.Hollow spindle wrapping spinning technology has distinct advantage in the reconstruction of yarn structures.This research work not only provides technical basis for high-quality and multifunctional processing,but also offers valuable insights into the application of the as-prepared wrapped yarns in personal protective fields.