Study On Hot Gas Welding Technology Of Heterogeneous Polymer Materials

Polymer materials have wear resistance,corrosion resistance,recycling and other excellent performance,because of its excellent performance,polymer materials have been rapidly developed in recent years,can be seen in many fields,such as aerospace,medical,semiconductor,automotive fields and so on.As a high polymer material,ultra-pure fluorine plastics(such as Polytetrafluoroethylene,PTFE)are often used in manufacturing ultra-clean fluid control parts in semiconductor field because of their corrosion resistance and low pollution.However,due to the viscosity of PTFE,it was difficult to bond with other materials.As another polymer material,the surface tension of Perfluoroalkoxy(PFA)was similar to that of PTFE at high temperature,and the PTFE was welded by hot air.At present,there are few researches on hot air welding of PTFE and PFA related heterogeneous polymer materials.In view of this,this paper carried out the following research:Firstly,the molecular dynamics simulation method was used to analyze the welding process of polymer materials from the microscopic scale.The simulation process mainly studied the influence of temperature on the diffusion and entanglement behavior of molecular chains at the interface of PTFE and PFA in hot air welding.The motion trend of the molecular chain between PTFE and PFA interface during hot air welding was discussed by using the diffusion coefficient calculated from the model as the evaluation index.It provides some theoretical guidance for the follow-up hot air welding experiment.Secondly,in view of the shortcomings of the existing hot-air welding device,the hot-air welding experimental system of heterogeneous polymer materials was built according to the actual hot-air welding process and welding process principle.The mechanical and electrical parts of the hot air welding device in the experimental system are selected and designed in detail.Finally,the hot air welding experimental system is manufactured and adjusted.Finally,the hot air welding process of heterogeneous polymer materials was investigated based on the established hot air welding experimental system.Taking the tensile strength as the index to measure the welding quality,the range of welding process parameters corresponding to the optimal welding quality was determined by single factor experiment.Using DesignExpert software,an experimental scheme for the interaction of multiple welding parameters was designed,and experiments were carried out.A mathematical model of welding strength and welding parameters was established by response surface method,which could predict the welding strength under different welding parameters.In addition,a set of optimal welding parameters were obtained with the maximum tensile strength as the optimization objective by genetic algorithm.