| Medical material is widely used in clinical medicine. A variety of human medical materials such as artificial ureters, artificial body cavity drainage tube, artificial venous catheters, artificial blood dialysis or peritoneal dialysis, artificial tracheal intubation, artificial heart valves, artificial bone, artificial vocal cords and other widely used. However, when the medical materials bring convenience to us, there are still some problems. We found that both long-term or short-term retention of medical materials in the human body, bacteria, fungi and other microbial pathogens would take a great harm to humans and animals,affectting people's health and even life-threatening.Microorganisms can also cause a variety of materials decomposition, deterioration, degradation, corruption, and bring significant economic losses.Ultra-high molecular weight polyethylene (UHMWPE) is a linear structure with excellent overall performance engineering thermoplastics and engineering plastics which is widely used in textiles, mining, chemicals, packaging, machinery, construction, electrical, medical, sports and other fields. The application of UHMWPE materials in the biomedical field is currently focused on joint replacement materials, tissue scaffolds, blood pumps, bags and other medical materials. The medical material has biological and health non-toxic inert, UHMWPE has received U.S. FDA approval for human implant materials, such as heart valves, artificial joints and implants such as birth control. Currently, there are hundreds of million people accept the acetabular component and metal artificial hip joint femoral that made from the UHMWPE, and its self-lubricating, anti-adhesive and non-coking led to UHMWPE have a good prospect in the machinery wear parts, artificial joints. But on antimicrobial and sterilization, the research about UHMWPE rarely reported.Currently, the improvement of antibacterial properties of biomedical polymers is mainly use the way that directly mix the antimicrobial agent into the parent material, to obtain the biomedical materials with antibacterial properties. This direct method is is simple and add the amount of antimicrobial agent can be accurately controlled, but the distribution of small molecule antibacterial agent in the polymer matrix materials is limited by the material compatibility with the antibacterial agent and the technology processing, the antibacterial agent is difficult to fully mix with base materials, thus relatively the antibacterial is poor. In addition, most antibacterial agents have a poor heat resistance, when used in the high melting point matrix material such as UHMWPE, it often lost the antibacterial because of the process of the pyrolysis process.In this thesis,we intercalate chlorhexidine acetate into the sodium montmorillonite to obtain a new modified packing which has properties of antibacterial, and then the paking was filled into UHMWPE, the mixture was blended in a Haake torque rheometer (Polylab 600). Compared with the traditional method, this method has the following obvious advantages:(1) Montmorillonite filled with antibiotics can effectively enhance the thermal stability of the antimicrobial agents, and increase the thermal decomposition temperature of antibiotics, conducive to the thermal processing.(2) The existence of clay and other layered fillers can reduce the migration rate of antimicrobial drugs, improve the drug stability of UHMWPE matrix. Montmorillonite also can melt and strip in the processing which lead to formation of nano-scale lamellar structure, then these can delay the drug release rate of composite materials to achieve long-term antibacterial.(3)The addition of small molecule antibacterial drugs can be played on the plasticization of the polymer, and nano-layered fillers can improve the dispersion ability of antimicrobial agents, so that the plasticization effect was further strengthened.This paper investigates the HAKKE torque rheometer mixing system to track UHMWPE at different temperatures and different speeds of the torque curve, determined the lowest processing temperature and the temperature of the specific processing conditions (screw speed, the proper temperature, etc.) in good processing performance. The results showed that:the good temperature is 195-200℃, when the speed is 60-70r/min.By the MMT as a matrix, add a series of synthetic antibacterial drugs Montmorillonite fillers, we obtained the organic/inorganic antibacterial filler. Then in the experiments conditions, the organic/inorganic antibacterial filler was filled in the UHMWPE, thus the composite materials with antibacterial function were got.The paper also used SEM, XRD,ATR-FTIR, static contact angle,TG,tensile test and rheological test system to characterize the composite materials, and the microstructure were studied and characterized. The results demonstrated that the modified functional Na-MMT filler could be completely exfoliated and dispersed in the UHMWPE matrix, forming a nano-scale composite. UHMWPE/CA-MMT showed hydrophilicity. Tensile test results also showed that elongation at break and Young's modulus had been greatly increased, CA-MMT could reinforce the UHMWPE. The rheology results showed that:CA decreased the storage modulus G', loss modulus G "and complex viscosityη* of UHMWPE/CA and UHMWPE/CA-MMT; MMT improved the viscosity of the polymer, increased the storage modulus G', loss modulus G "and complex viscosityη* of UHMWPE/MMT.The basis of the above work, the bacterial adhesion experiments and antibacterial plastic film testing method were used to test the the antibacterial properties of the composites to determine the antibacterial effects. The results showed that:UHMWPE /CA had some antibacterial, CA improved the antibacterial ability of UHMWPE in a certain extent; UHMWPE/CA-MMT had the least distribution of bacteria and E. coli becomed dry, wrinkled and the overall shape has been lost, indicating that the bacteria that adhered in UHMWPE/CA-MMT surface had been killed and the antibacterial effect is obvious.In addition,long-lasting anti-bacterial effect is very prominent (21 days).The thesis investigated the crystalline morphology of composites and the crystallization kinetics by DSC.We found that the heterogeneous nucleation apprared in the composites.MMT increased the values of the reaction rate constant K. |
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