| The applications of biological polymer materials (medical sutures, Intravenous infusion sets, catheter, etc) and artificial organs (artificial heart valves, artificial bone, artificial vocal cords, etc) are increasingly widespread, however, during the process of using, there are a few problems, especially bacterial infections lead to the most serious consequences and that can't be ignored. In the clinical application of medical polymer materials how to make polymer materials with antibacterial properties has become the hot topic of the biomedical polymer materials.The scientific community generally believed that bacterial biofilms play a major role in bacterial infection at present. Very troublesome as the treatment of biofilm-associated infections diseases, currently used inorganic metal ions and organic groups as antibacterial groups. Whether it is natural or inorganic material and organic anti-bactericidal, although the mechanism not the same, the ultimate goal is to destroy the cell wall or membrane of the internal and external systems.The manner of the introduction of an antimicrobial group mainly uses physical methods. Currently, for antibacterial materials of biomedical polymer, the most practically valuable physical method is that the antibacterial agent is directly added to the base material to obtain a medical material of the biopolymer, which has the antibacterial properties. The operation of this antibacterial agent added directly to the physical methods is simple, and that the amount of antimicrobial additives can be accurately controlled. It is able to be industrial produced in large scales and it has a strong practical value. But the dispersion of the antibacterial agent as small molecules in the polymer matrix material is influenced by the compatibility of the materials and antimicrobial agents and the processing technology. Antibacterial agent is easy to reunite and precipitate, it is difficult to fully uniformly mixed with the polymer materials, so the antibacterial effect is relatively poor.As the extensive application of the poly-lactic acid, polysulfone, polyurethane, poly-caprolactone, and other materials in the field of medical products, biomedical polymer material shows an absolute advantage in the field of biomedical materials. Among which polyurethane is more superior in mechanical properties and biocompatibility, and that its structure can be improved through the change of the reagent parameters. Therefore it is regarded as the main raw material for prepared medical products.We used disinfection antiseptic medicine of chlorhexidine acetate, which road-spectrum antibacterial and bactericidal effect is very obvious. It has significant antibacterial properties in Staphylococcus aureus, Escherichia coli and Candida albicans. It can maintain the growth or reproduction of the certain microorganisms (bacteria, fungi, yeasts, algae and viruses, etc.) under the necessary level within a certain time. Dissolve the traditional antimicrobial agents acetate chlorhexidine in the solution, get the solution intercalation into montmorillonite (MMT) interlayer to obtain modified nanoscale composite MMT-CA antibacterial agent filler. Then the obtained filler of antibacterial agent and the polyurethane (PU) is melt blended in a HAAKE torque rheometer to get antibacterial properties of the nanocomposite master batch. Compared with the traditional way that add antimicrobial agent directly, this method has several obvious advantages:(1) Inhibition zone and slow-release experiment can prove that intercalate antimicrobial drug into montmorillonite (MMT) fillers can significantly improve the stability of chlorhexidine acetate antibacterial drugs and significantly improve thermal decomposition temperature, so we can guarantee that there's no loss of antibacterial drugs in the thermal processing.(2) MMT has good dispersion properties to improve the impact resistance, fatigue resistance, dimensional stability of the polyurethane polymer materials, and thus play a role in enhancing the physical properties of the polymer, while improving the performance of material processing. The presence of the layered filler allows that the mobility of the antimicrobial drugs reduces, and enhances the stability of the antimicrobial agent in the PU masterbatches. While the layered filler processing at elevated temperature, molten peeling occurs and gets the layered structure of the nano-scale, so that the rate of drug release is delayed and long-acting antimicrobial and antibacterial of material is obtained.(3) Adding small molecular antimicrobial agents can plasticize polymer. Layered nano filler can improve the dispersibility of the anti-microbial drugs while allowing such a plasticizing effect to be further strengthened.Firstly, we can determine the best experiment processing conditions through a number of tests. On the basis of the experiment, we can prepare polyurethane nanometer antibacterial material with antibacterial function through adding the mixer of nanoscale CA-MMT antibacterial agent to the master batch of polyurethane material.The result shows that:the speed of HAKKE is 65-75r/min, the temperature is 145-155?, polyurethane resist obtained by processing for 6 min is the most suitable materical for the requirements.We also studied the changes of the interlayer spacing of MMT to judge whether it was successful that the CA intercalated layer spacing, finding that of MMT increasing significantly. It demonstrated the success of CA intercalating MMT and tested the microstructure of Na-montmorillonite?Chlorhexidine acetate and CA-MMT using FTIR. It analyzed the inserted condition of antibacterial through the absorption spectrum, thermal stability of CA-MMT through TG, the inserting condition through grain size test, the antibacterial condition of nanometer antimicrobial through anti-bacteria circle test, delivery system of CA-MMT through slow-release experiment, the hydrophilicity and hydrophobicity of composite material through static contact angel test and the rheological properties of the composite materials through the rheology.The experiment above provided a possibility for the material antibacterial properties. In order to test antimicrobial properties of antibacterial material truly, this paper used pasting antibacterial experiment and bacteria adhesion experiment and so on to test and verify the antibacterial property of antibacterial material. The experimental results showed that the addition of CA-MMT plays a significant antimicrobial effect, high temperature resistant increased significantly compared to CA and CA-MMT, and could adapt to the temperature of the processing conditions. Amount at stake is very little in the course of processing, at the same time, it can release from material more easily because CA-MMT was stripped in material.The antibacterial material realized the long-term antimicrobial effect of antibacterial material.This paper also studied and analyzed the thermal stability of the composite material and had a analysis of heat resistance and anti-aging through the Flynn-Wall-Ozawa method and Coats-Redfern method.And PU/CA-MMT materials showed more excellent thermal stability and heat aging ability. |
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