Preparation And Electrothermal Properties Of Graphite Nanoplates Composite Films

With the development of society,electric-thermal materials are more and more applied to thermotherapy,electric heating and other fields.Conventional electric-thermal materials are divided into two categories: metal resistance wire?Ni-Cr,Fe-Cr alloy?and ceramic heating materials.The metal resistance wire have some shortcomings,such as heavy weight,low heating efficiency,brittleness and uneven heating.And the solderability of the alloy is poor,it is difficult to repair after damage.Ceramic heating material has the disadvantage of slow heating rate,and has a large brittleness,poor vibration resistance.These shortcomings of metal and ceramics limit their use in aerospace,electronics,electrical,automotive,military,medical and other industries.Therefore,it is very important to study the new electric-thermal materials with the advantages of good flexibility,uniform heating and high electric conversion efficiency.In this paper,graphite nanoplatelets?GNP?were used as conductive superconducting prepared light-weight and flexible electro-thermal films,and their electrothermal properties were investigated.Firstly,graphite nanoplatelets solution was respectively mixed with carboxymethylcellulose sodium?CMC?,waterborne polyurethane?WPU?,silicon-acrylic latex?Si-Acr?three kinds polymer subsequently,then the graphite/polymer composite films were prepared for the conductivity,mechanical properties,water resistance testing.Finally,WPU was used as binder to prepare flexible electro-thermal film.The ratio of GNP and WPU in the composite film is 1:1,the tensile strength of the composite film is 18 MPa,the resistivity is 48.4m?·cm.Then the composite film was immersed in water for 15 min,the resistivity is only increased by 0.8%.The composite film was connected to the circuit for thermal performance testing.It was found that the relationship between power density of GNP/WPU composite film and the electrode spacing,the voltage across the electrode,thesquare resistance of GNP/WPU composite film was P₀=U²/R_?L²,and the power density was proportional to the surface temperature of heating film.Use of GNP/WPU composite film to prepare the physical care knee,which can be in the capacity of 10000 m A,the voltage of 5V charging Po continued to work for 6hours.Wear the heating temperature is stable at about 45?,the upper and lower temperature difference is only about 3?.Next,GNP/WPU mixed solution was applied to the floor as a heat-generating coating by brushing to prepare a heated floor.In order to ensure the uniformity of the surface coating during the brushing process,a certain amount of surfactant was added to the mixed solution.Finally,the ratio of GNP,WPU,surfactant in mixed solution is 10:10:1.The concentration of the slurry was 50mg/ml.The thermal performance of the heating floor was explored and found that the temperature difference between front and back of the insulating layer was about 4?.When the final temperature is stable,the difference in temperature difference between the upper and lower surfaces of the floor is about10?.The floor was connected to circuit for 7 days,found that the floor temperature is stable,the temperature difference is only about 3?.Finally,a flexible driver was prepared by using GNP/CMC composite film and PI,PET,PDMS and PETF respectively.It was found that the binding force of GNP/CMC composite film was the best and the response speed was only 4.5s when PI was used as substrate.In the study found that the bending effect of the drive,which with PI substrate thickness first increased and then reduced.Finally choice thickness of 80?m PI made the drive.The actuator of U-shaped structure can be bent at a maximum angle of 270° in 10 s at a voltage of 12.5V,and continuous turn off after 100 times can still maintain the initial bending state.The prepared hand-type driver can simulate grip at the voltage of 48 V to grasp a4 g heavy paper group.