Theoritical And Experimental Study On The Gas-assisted Extrusion Of Antibacterial Medical Catheters

With the wide application of catheter-interventional therapy in clinical treatment,the catheter-related infection has become an important problem that must be faced,studies have found that the use of antibacterial catheters is an effective way to prevent such infections.The conventional manufacturing methods of antibacterial catheters include substrate mixing,surface modification,impregnation,etc.,but there are obvious shortcomings of each,such as complicated and harsh production processes.It is necessary to explore a new preparation mechanism and method to realize the convenient and efficient preparation of antibacterial medical catheters.The gas-assisted extrusion method is to create a gas film between the melt and the die wall,so that the polymer extrusion process is converted from non-slip sticky extrusion to complete slip non-stick extrusion,thereby greatly reducing die pressure drop,thereby alleviating the extrusion swell and melt fracture problems,and finally achieve high-speed high-quality polymer extrusion.Based on the characteristics of gas-assisted extrusion,the antibacterial material is loaded into the gas used for gas-assisted extrusion,and the antibacterial material is transported to the surface layer of the catheter with the aid of the auxiliary gas to form a functional layer doped with the antibacterial material.It is possible to obtain medical catheters with antibacterial ability,and creating a new method of manufacturing antibacterial medical catheters using a gas-assisted extrusion process.Focusing on the goal of extruding antibacterial medical catheters by gas-assisted method,this paper carries out research from both numerical simulation and experiment.The main contents are summarized as follows:1.Study on the mechanism of gas-assisted extrusion of catheters.Establish a "gasmelt-gas" coupled flow model,integrate polymer rheology,gas-liquid multiphase flow and computational fluid dynamics theory,explore suitable numerical solution methods,and analyze the gas-assisted extrusion molding process of single-lumen catheters.The velocity field,temperature field,stress field distribution and phase interface position of multiphase flow in and after die separation in the process of gas assisted extrusion were analyzed by numerical simulation.The main factors and influencing rules affecting the morphology and stability of extrusion process were studied,which provided direction guidance for the later use of process parameters and flow path parameters to control the shape and size of extrusion.2.A gas assisted extrusion experimental system of antibacterial medical catheter was constructed.On the one hand,the structure of the gas-assisted extrusion die was redesigned,in order to solve the problem of blowing the microtubes after the inner auxiliary gas flows into the microtube lumen,and at the same time reduce the sensitivity of the gas-assisted extrusion process to the fluctuation of process parameters;On the other hand,an antibacterial material aerosol generator is designed,which prepares the antibacterial agent aerosol by means of agitation and fluidization combined with high-speed airflow impact.Based on these,an antibacterial medical catheter gas assisted extrusion experimental system including extruder,gas control and transportation system,gas assisted extrusion die and antibacterial material aerosol generator is constructed.This system can provide hardware support for the preparation of subsequent antibacterial catheters.3.By carrying out the experimental research on the gas-assisted extrusion of antibacterial medical catheters,the influence rules of process parameters and mold flow channel parameters on the appearance size of antibacterial catheters and the distribution characteristics of antibacterial materials were found;The antibacterial performance of antibacterial catheter was tested and evaluated to verify the feasibility of extruding antibacterial medical catheter by gas assisted method.