Design And Thermal Properties Of Typical Electrothermal Polymer Matrix Composites

The electrothermal composite material has excellent electrical conductivity,which enables it to use joule effect to convert electrical energy into heat energy without producing other unwanted toxic and harmful substances.It is considered to be the most efficient and clean heating product in the 21st century.Based on its efficient electricity-heat conversion capability,electric heating products are believed to be widely used in home heating,outdoor deicing,physical therapy and health care,mist and frost removal and other fields.But with the continuous development of the progress of the society and economy,electrothermal products with single electrothermal properties have been difficult to meet the complex needs of some industries,for example,the electric heating material used for the window surface of vehicles needs to have transparency.Therefore,the development of electric heating composite materials with multiple functions will further expand the practical application range of electric heating products.In this paper,on the basis of collating a large number of electrothermal materials,for the problem of single performance of traditional electrothermal materials,several multifunctional electrothermal composite materials were prepared.Through the scanning electron microscope(SEM),infrared thermal imager(IR),four-point probe,numerical control temperature measurement and other test methods,the dispersion state of the conductive filler in the electrothermal composite material and its effect on the electrothermal performance of the electrothermal composite material were studied.In addition,specific research has been conducted on the versatility of specific electrothermal composite materials.The specific work is as follows:1.A small amount of CNT was coated on the surface of APP with excellent flame retardant performance by micro-encapsulation technology to form CAPP,and then it was blended with CCB and EVA to prepare an electrothermal composite with excellent thermal performance and flame retardant performance.Research results showed that CAPP had a better dispersion in the polymer than APP,electrothermal composite material using CAPP and CCB synergistic conduction compared with electrothermal material using CCB alone,the electrical conductivity increased nearly 10 times.Its surface temperature can reach 100? under the applied voltage of 18V,and it can work stably for more than 3600s under the applied voltage of 15V.At the same time,it went through 12 cycles of heating-cooling process without obvious deviation of the temperature curve.Compared with pure EVA materials,the electrothermal composite materials used CAPP and CCB synergistic conduction showed a significantly higher initial thermal decomposition temperature,and the residual carbon rate increased by nearly 38.5%under N2.At the same time,the value of HRR was reduced by about 73.6%and the value of LOI was increased from 17%to 31%,and it could pass the V-0 test of UL-94.The test results showed that the electrothermal composite material had excellent electrothermal and flame retardant properties.2.Several PVA electrothermal composite coatings with 0-d CCB as the main conductive filler,1-d CNT,AgNW and 2-d MXene as the synergistic conductive filler were prepared by solution method.MAPP was prepared by wrapping MXene on the surface of APP by microencapsulation technology and was introduced into PVA electrothermal composite coating to give it flame retardant properties.Research results showed that the AgNW and MXene with CCB has better association effect.The corresponding electrical conductivity was increased by 31.2%and 45.5%respectively compared with the electrothermal composite coating used with CCB alone.The introduction of MAPP improved the electrical performance of the electrothermal composite coating,and the electrical conductivity was 66.5%higher than PVA-3.PVA-3,PVA-5,PVA-6 and PVA-10 can all reach temperatures above 100? at the corresponding voltages.The temperature response time was extremely short,and they all showed excellent cyclic heating performance and long-term heating performance.Compared with pure PVA,the initial pyrolysis curves of PVA-3,PVA-5,PVA-6 and PVA-10 were all significantly delayed.The rate of carbon residue increased by 40.53%,42.78%,43.78%and 48.80%,respectively.At the same time,the foam combustion experiments showed that PVA-10 can completely inhibit the foam combustion.The test results of electrothermal composite coating showed that PVA-10 had excellent electrothermal and flame retardant properties.3.CCB,CNT,MXene and AgNW were used as conductive materials to construct conductive network on cotton fabric by dip-coating method to prepare electrothermal composite fabric.Research results showed that a conductive network was constructed on the surface of the electrothermal composite fabric.The surface temperature of the electrothermal composite fabric AgNW could reach more than 100? at the applied voltage of 2V,and it could maintain a excellent cycling heating performance at the applied voltage,with a good electrothermal performance.Time-temperature curve of the electrothermal composite fabric AgNW-10-3 coated with a small amount of waterborne polyurethane did not change significantly after bending 50 times and after solvent impregnation.In addition,the electrothermal composite fabric could generate heat uniformly at the wrist in the wearing test.