Preparation And Properties Of Carbon Based Conductive Composite Yarn

With the advent of the intelligent era,the application field of intelligent manufacturing by researchers has gradually expanded to the frontier fields such as medical health and humancomputer interaction.As the sensing element of intelligent system,high-performance flexible sensor is an indispensable link in intelligent wearable products.Fiber based clothing has been used by human beings for thousands of years.Because of their ultra-high fit and rich physical and chemical properties,they are ideal substrate materials for the preparation of flexible sensors.In this project,carbon nanotube inks are self-made.On this basis,the preparation methods of two carbon based conductive composite yarns are discussed,and their structures and related properties are studied,including mechanical properties,electrical conductivity,strain sensing properties,durability,stability,electro-thermochromic properties and wearable applications,The specific research contents are as follows:In the first part,the carbon nanotubes were acidified,and the hydrophilic groups such as carboxyl and hydroxyl groups were successfully introduced into the surface of multi walled carbon nanotubes to prepare the dispersion of multi walled carbon nanotubes with stable properties;Carbon nanotube ink was prepared by mixing waterborne polyurethane with acidified carbon nanotube.The influence of washing times during the processing of acidified carbon nanotube in the acidification process and the influence of the amount of waterborne polyurethane on the structure and conductivity of carbon nanotube ink were explored.In the process of conductivity verification,the pretreatment conditions and process parameters in the preparation of carbon nanotube / polyurethane composite conductive yarn were determined,and the formula of waterborne conductive ink was obtained.In the second part,the conductive carbon nanotube / wool top was coated on the surface of polyurethane yarn by friction spinning machine to prepare carbon nanotube / wool /polyurethane conductive composite strain sensing yarn（CWPY）.Benefiting from the good performance of wool,it can be well combined with carbon nanotubes,and make the conductive composite yarn have high conductivity（1.80 Ω·cm）,air permeability and rich hand feeling.Using polyurethane yarn as core yarn and friction spinning technology,multi scene wearable strain sensor is developed to simulate complex human mechanical stimulation,and explore the strain sensing mechanism of flexible conductive composite yarn.The conductive composite yarn shows excellent durability（>1000 cycles）,high sensitivity and wide strain range（0-180%strain）,which provides a reference for the next generation of personal health care wearable intelligent textiles.In the third part,the electro-thermochromic carbon nanotube / polyurethane composite yarn（ECPY）with core–sheath structure is constructed by impregnation and electrospinning,so as to obtain electro-thermochromic composite yarn with rich color.The results show that the temperature can be rapidly increased to 66 °C by applying a low voltage at both ends of the composite yarn,and electro-thermochromic can be realized.The chromatography can be realized by changing the type of color changing ink,and the different patterns of color changing textiles can be obtained by weaving.In addition,the composite yarn has excellent conductivity,high sensitivity,wide strain range（0-310% strain）and excellent durability（>2000 cycles）.This is conducive to the development of wearable electronic strain sensing and health monitoring applications.