Study On Heating And Sensing Properties Of Carbonized Polyacrylonitrile Nanofiber Membran

Flexible wearable components are lightweight,flexible,intelligent and efficient,and have transformative potential for the development of future wearables.With increasing demand in individual thermal management fields,high-performance multi-functional high wearable electronics is the application of human health requirements,such as intelligent temperature sensor electric heating clothing and wearable heat treatment unit,the application of both rich people,to offer low temperature and workers and easy cold old people life,has a certain economic and social benefits.In this paper,polyacrylonitrile（PAN）was used as raw material to prepare carbon nanofiber/thermoplastic polyurethane composite film（CNFFs/TPU）by electrostatic spinning process,pre-oxidation process,carbonization process and impregnation drying method.The influence of carbonization temperature on surface morphology,Raman spectrum,electrical properties,wettability and mechanical properties was analyzed.Secondly,multi-functional flexible fork finger electrode was designed and manufactured,and CNFFs/TPU and fabric were combined to prepare flexible heating sensing element（CNFFs-HSE）.Combined with heat transfer theory,the influence of carbonization temperature on fixed specification OF CNFFs-HSE electric heating performance was analyzed,and the thermal stability of CNFFs-HSE was tested.Then,the sensitivity,hysteresis and repeatability of the flexible piezoresistive sensor are tested according to the above factors.Finally,practical application tests（e.g.pulse and elbow movement）were performed.The results show that the pre-oxidation process can keep the molecular chain stable in the carbonization process,and the carbonization process can turn pan nanofibers into graphitized carbon nanofibers.After several drying and impregnation treatments,TPU is uniformly coated on the fiber surface.CNFFs/TPU has good flexibility,electrical conductivity and bending resistance.Carbonization temperature affects the heating performance and sensing performance of CNFFs-HSE.CNFFs-HSE-1000 composite film has a square resistance of 28.83Ω/sq,and can be rapidly heated to 64.73℃at 4 V voltage with a temperature difference of 6.15%.The maximum equilibrium temperature is highly linearly correlated with the power density,showing good heating characteristics,surface temperature uniformity and thermal stability.It also has high sensitivity(83.022 KPa^-1),low hysteresis（23.2%）and good stability（≥3000 times）.Therefore,CNFFs-HSE based on the preparation of carbon polyacrylonitrile nanofiber membrane heating physiotherapy can also be real-time monitoring of human physiological signals,such as pulse monitoring and elbow movement monitoring,in the human body cold and warm,health physiotherapy,health monitoring and disease diagnosis has great application potential.