Microwave Controllable Positioning Welding Of Thermoplastic Materials

In recent years,due to the expanding application range of polymer materials,traditionally shaped materials have been unable to meet the needs of production and life.Various welding methods have been introduced.In this paper,the major work is to realize the microwave positioning welding of thermoplastic materials.And the following contents are carried out:Graphite powder(GP)liquid solders were prepared and used for microwave welding of thermoplastic polypropylene(PP)substrates.The relationship between the interface strength of PP/GP/PP samples and solder quality,graphite powder type,graphite powder content,solvent type,microwave welding time and pressure was investigated.When 0.03 g of solder 3 prepared by ball-milled graphite powder and ethanol solvent welding 75 s with the pressure of 156800 Pa was used,the interface strength of welded sample reached 587 N,which exceeded the bulk strength of PP substrate.The microwave positioning welding is achieved by controlling the coating position,size and shape of the liquid solders.Carbon nanotube(CNT)liquid solders were prepared and used for microwave welding of PP substrates.The relationship between the interface strength of PP/CNT/PP samples and the CNT content,the time of microwave irradiation and the pressure was studied.The morphology and electrical performance of the welded area were analyzed.When the No.1 CNT solder welding for 40 s with the pressure of 156800 Pa is used,the welding strength reached 755 N,which is much larger than the bulk strength of PP substrates.GP/TPU solid solders were prepared and the effect of welding thermoplastic polyurethane elastomer(TPU)in microwave field was studied.The relationship between the interface strength of TPU/GP/TPU samples and the thickness of solid film,the content of GP,microwave irradiation and pressure was investigated.The microscopic morphology,the elasticity and the recovery ability of the welded area were studied.The implementation method of the film solder in microwave positioning welding was summarized and the advantages of solid solders were analyzed and compared.When the No.1 solid film solder was used for microwave treatment for 60 s with the pressure of 156800 Pa,the interface strength of the thin neck welding sample and the head welding sample reached 48.03 N and 98.53 N respectively,both of which were greater than TPU body strength.Through the custom cutting and spreading of GP/TPU film solder,the size,shape and position of the welding area are controlled and the precise controlling can be achieved.Dedicated microwave welding equipment was designed and prepared by combining a vacuum system,a hydraulic system and a microwave welding system.The idea of completing the microwave welding of shaped materials by means of welding auxiliary box was proposed,which provided a new idea for the processing of thermoplastic materials.