| In garment microclimates,temperature and pressure are important factors influencing garment comfort.Active thermal garments with integrated flexible heating elements can intelligently regulate the internal temperature of the garment,while changes in pressure between the heated garment and the skin affect the thermal comfort of the human body.Therefore,the study of multifunctional flexible fabrics with integrated heating elements and pressure sensors is of great significance for enhancing the comfort and intelligence of garments.Firstly,the thermal stability and mechanics of the carbon nanotube film and hot melt adhesive bonded fabric were tested,and the electrical and thermal properties and softness of the flexible heating element prepared by the hot press bonding process were tested.The results showed that after 24 days,the change in resistance of the carbon nanotube film was 11.84%and 17.81%at 60°C and 80°C temperature aging environments respectively.The average peel strength of the three-layer fabric with the carbon nanotube film was 6.775 N at 170°C and 60 s.The average peel strength increased to 17.811 N and the fracture strength was 805.68 N after 30 days of ageing at60°C.The single,parallel two-piece and parallel three-piece flexible heating elements were tested at 50.29 m W/cm2,51.68 m W/cm2,and 52.47 W/cm2 at power densities of59.12°C,58.89°C and 60.78°C,respectively.When the bending rate was 80%,the stresses for the three heating elements were 19.2 c N,12.7 c N and 15.8 c N respectively,reflecting the corresponding softness.Secondly,10wt%multi-walled carbon nanotubes（MWCNTs）/polyurethane（PU）porous conductive films were prepared using a non-solvent induced phase transition（NIPS）method combined with 150-,240-,320-and 400-mesh sandpaper templates,and their mechanical and sensing properties were investigated.The results show that the micro structured conductive film replicated using 240 mesh sandpaper templates can achieve a sensitivity of 63.47 k Pa-1 at 0.5 k Pa,with a hysteresis error of 8.45%and good stability and repeatability over 4000 load-unload cycles.The flexible piezoresistive sensor based on the conductive film has good response characteristics when tested by finger press and bending.Finally,a multifunctional flexible heated fabric with pressure sensing was prepared by screen printing,in which the flexible piezoresistive sensor showed a resistance change of 16.88%and a temperature coefficient（TCR）of-0.014ppm/°C after cycling up and down the temperature.Tested in applications on the elbow,knee and foot,the fabric showed good temperature and motion signal response characteristics.In practice,the flexible heated fabric can be heated and regulated according to the pressure to enhance the comfort of the garment,which can be widely used in the fields of human motion detection,thermal therapy,intelligent clothing and apparel and sports protection. |
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