Preparation And Electromechanical Properties Of Multifunctional Graphene/Fabric Composites

With the development of wearable electronic devices,smart textiles have been widely used in sports,military,defense,aerospace and other fields due to their unique sensing,response,and feedback mechanisms.Smart textiles are new types of textiles that use conventional textiles as a carrier and combine electronic components.They are generally composed of sensors,actuators,data processing part,communication part,and power supplies part.The preparation of flexible sensors and conductive circuits is the key to the multifunctionality of smart textiles.The traditional electronic sensing elements and conductive wires have low coupling with the fabric,which seriously affects the performance of the fabric itself.Achieving the flexibility and multifunctionality of electronic sensing elements is the focus of current smart textile.Therefore,in this thesis,graphene and fabrics with different dimensions are combined due to their unique properties,including the unique physical and chemical properties（graphene）and the excellent designability and wearability（fabric）.Two-dimensional（2D）graphene/2D fabric and three-dimensional（3D）graphene aerogel/3D spacer fabric were constructed in detail.The research focused on their mechanical-electrical properties and explored the versatility.Then the compression and anti-impact properties of the composite were studied by experiments and finite element numerical simulation methods.The specific research contents and results are as follows:（1）Research on the mechanical-electrical piezoresistive properties of 2D graphene/2D fabric multifunctional composites:graphene was deposited on silk fabrics by suction filtration and hot pressing process,and fabric sensors with different fabric angles were prepared.The results of mechanical-electrical properties show that the curves ofΔR/R₀ and tensile（compressive）strain exhibit a good linear relationship;it has a tensile sensitivity of 124（at a strain of 10%）,and compressive sensitivity of 25（at a strain of 4%）;As the fabric angle increases,its sensitivity decreases,and the linearity between resistance change rate and strain weakens;the gauge factor and stability are excellent,and it can also detect changes of human facial expressions and finger movements.The sensing mechanism is attributed to the initiation and propagation of microcracks.（2）Research on the mechanical-electrical piezoresistive properties and multifunctionality of 3D hybrid graphene aerogels:graphene-based aerogel hybrided with silk fibroin（SF,Silk Fibroin）were prepared by freeze-drying and reduction methods.The results of mechanical-electrical properties show that silk fibroin can promote the formation of graphene oxide（GO,Graphene Oxide）sheet network,and the mechanical and sensing properties of hybrid graphene aerogels are improved,with a sensitivity of 11.44（at a strain of 5%）.The hybrid graphene derivative aerogel has excellent adsorption properties for methylene blue dye and heavy metal ions（copper ion and zinc ion）.The adsorption kinetics results show that the adsorption process is in accordance with the pseudo-second-order kinetic model.（3）Research on the mechanical-electrical piezoresistive properties and multifunctionality of 3D graphene aerogel/3D spacer fabric multifunctional composites:firstly,the hybrid graphene aerogel and spacer fabric was combined to construct a multifunctional structural sensor.The structure sensor has a strain sensitivity of 1.48,a response time of 40 ms,and can detect rice particles as light as 26.78 mg;it also has a temperature sensitivity of-0.004°C^-1 and a protection factor of 45%（50 cycles of impact experiments）.The internal conductive structure network of the sensor is composed of graphene aerogel,and the spacer fabric endows the sensor excellent anti-compression and anti-impact performance.Then,the compressive behavior of the spacer fabric was numerically simulated by finite element software（ABAQUS）,and the numerical simulation results indicated that smaller inclination angle,smaller height of spacer filament,and larger diameter of spacer filament have obvious enhancing effects on its compressive properties.In addition,the electrochemical test results of the hybrid aerogel/spacer fabric electrode show that the cycle stability is excellent.Its capacitance retention rate is still 98.9%even after 14,000 charge-discharge cycles.The CV curve hardly changes when the composite fabric electrode is loaded with a weight of 1000 g,showing good deformation resistance.（4）Research on the mechanical-electrical piezoresistive properties of silicone rubber/3D graphene aerogel/3D spacer fabric composites:the aerogel/spacer fabric composite was combined with silicone rubber by coating method to prepare a spacer fabric-based structure sensor.The compression and impact mechanical properties,sensing properties and applications were systematically studied.The results show that after compounding with silicone rubber,the mechanical properties and sensing properties of composites are greatly improved,and it has a sensitivity of 17.71（at a strain of 40～55%）;the impact-sensing performance is excellent even after 50 cycles of impact,and the protection factor is 55%.By constructing a hyperelastic constitutive model,its compression and impact behaviors were studied by numerical simulation.The simulation results show that the constitutive model can be used to describe the compression and impact behavior of this silicone rubber/aerogel/spacer fabric composite,which provides guidance for the theoretical analysis and numerical simulation of this type of hyperelastic material.In summary,the preparation,mechanical-electrical properties and sensing mechanism of graphene/2D fabric,graphene aerogel/3D spacer fabric,and silicone rubber/graphene aerogel/3D spacer fabric composites were investigated systematically.Numerical simulation and experimental methods were combined to study the compression behavior of spacer fabrics,the compression and impact behavior of silicone rubber/graphene aerogel/3D spacer fabric composites.The research results have important guidance for the preparation,performance evaluation and application of multifunctional fabric composites.