Study On Conductive Polymer Composites Based On Electrospun Fiber Network And Its Strain Sensing Performance

Recently,the adjustment of the structure and performance of conductive polymer composites(CPCs)have received widespread interests.Strain sensor as one of the most fascinating applications for CPCs,has been demonstrated promising potential for electronic skins,personal health monitoring and damage detection,etc.In this context,a novel strategy was proposed to manufacture CPCs based strain sensors by embedding conductive electrospinning polyamide 6(PA6)fiber network into the poly(vinyl alcohol)(PVA)matrix.We investigated the structure and performance of this kind of strain sensor in detail,and the main results are as follows: 1.The fabrication and performance of carbon nanotubes(CNTs)-coated PA6/PVA compositeAs we all know,CNTs with eminent electrical conductivity and mechanical properties are always utilized as effective raw materials to construct CPCs based strain sensors.Nevertheless,only few CNTs based strain sensors prepared by the conventional solvent or melt process have excellent mechanical,conductive and strain sensing properties.One possible reason is that when CPCs are used as strain sensors,the fixed CNTs content is usually high in order to get the repeatable and recoverable response behaviors.Unfortunately,the aggregation of CNTs at higher CNTs content is more obvious and generally causes the loss of the mechanical properties.Thus,there is still a challenge to prepare a CPCs based strain sensor with excellent integrated performance.In the present paper,a novel strain sensor was fabricated by incorporating CNTs-decorated PA6 nanofibrous network(CNTs-PA6)into the PVA matrix.Mechanical,conductive and strain sensing properties of CNTs-PA6 nanofibrous membrane were firstly investigated,which provides the experimental basis for tuning the structure and performance of CNTs-PA6/PVA composite.For the composite,CNTs were employed to pre-construct the conductive network by decorating the surface of the electrospun PA6 nanofibrous network.The effects of CNTs content and the number of the CNTs-PA6 layer on tensile properties of the composite were investigated.To balance the electrical and mechanical properties of the composite,two layers of CNTs-PA6 membranes were embedded into the PVA matrix in parallel.Under uniaxial tension tests,the composite with two layers of CNTs-PA6 membranes(CNTs-PA62/PVA)showed a stepwise change in resistance,which can be utilized to detect the damage evolution of the composite.Performing cyclic tensile tests revealed that CNTs-PA62/PVA composite exhibited distinguishing response behaviors toward different deformation levels(such as the difference in the Rmax/R0 drifting or the intensity of the shoulder peak),which contributed to identify the damage status of the nanofibrous conductive composite as a novel self-diagnosis probe.In addition,the recoverability and repeatability of the strain sensing behaviors could be tuned by pretreatment(dozens of elongation/contraction cycles or pre-stretching).2.The fabrication and performance of carbon black(CB)-coated PA6/PVA compositeThe conductive network constructed by CB usually has a sensitive response to external stimulus due to the lower dimension of CB(zero dimension).Therefore,CB was used as the substitution of CNTs to construct the CB-decorated PA6 fiber/PVA composite.The strain sensing behaviors of CB-PA6/PVA were studied in detail,and the composite possessed satisfactory recoverability,repeatability and durability.In addition,the different strain sensing behaviors between CB-PA6/PVA and CNTs-PA61/PVA composites could be induced by the geometry of the fillers.The present study opens up new opportunities to develop a nanofibrous network based tunable strain sensor with excellent integrated performance for damage detection.