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Control of the Microstructure of Cu/ldpe Composites and Its Influence on Their Properties

Author: TangZuo
Tutor: XieChangSheng；XiaXianPing
School: Huazhong University of Science and Technology
Course: Materials Science
Keywords: Cu/LDPE composites microstructure control mechanical property cupric release hydrophilicity
CLC: TB333
Type: Master's thesis
Year: 2011
Downloads: 32
Quote: 1
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Abstract


The traditional Intrauterine Device(IUD)is a T-shaped device consisting of several sections of copper wires or copper tubes wrapped around a polyethylene stem, which contains BaSO4 filler as developer, and the releasing rate of cupric ions can only be controlled by changing the surface area of copper. The novel IUDs are prepared by Cu/LDPE composites, whose copper particles are dispersed in the matrix of LDPE, and the control of the microstructure of composites is an effective method to regulate the releasing rate of cupric ions.As the material of IUDs, the major properties need attention in clinical are the release of cupric ions, the mechanical property and the biocompatibility. To improve the above properties of IUD materials, the selection of material and the process of production are two aspects that were taken into consideration to control the microstructure of Cu/LDPE composites. Besides, the UV irradiation was used in order to improve the surface hydrophilicity of materials in the present paper.The factors of material selection include the size and content of copper particles, the particle size of LDPE, and the types and amount of pore-forming agent. Sodium chloride, anhydrous glucose and soluble starch were chosen as three pore-forming agents because of their excellent body compatibility. In order to investigate the releasing property of cupric ions, variousγ-shaped Cu/LDPE composite IUDs were immersed in simulated uterine fluid with the constant temperature of 37.5℃, and the concentration of cupric ions was measured using the UV-Vis spectrophotometer. The results showed that, for the Cu/LDPE composite IUDs, the release amount of cupric ions increased with the increase of the content and size of copper particles and with the decrease of the particle size of LDPE. The addition of all the pore-forming agents increased the release amount of cupric ions. The mechanical properties of Cu/LDPE composites were investigated by means of tensile test using standard tensile samples. The elongation at break, the tensile strength, and the elastic modulus were three evaluating parameters. The testing results showed that, the mechanical property of Cu/LDPE composites exhibited a complex regularity with the changing of copper content and the particle size of copper and LDPE. The addition of various pore-forming agents all reduced the mechanical property of Cu/LDPE composites, especially NaCl. Besides, wetting ability of various composites was evaluated by measuring the static contact angle using distilled water and SUS. The result showed that, majority of microstructure control methods had few influence on improving the surface hydrophilicity of Cu/LDPE composites, except the addition of pore-forming agents.The factors of production technology include the injection molding temperature and reuse times of scrap, aiming at providing the experimental evidence for the choice of injection molding temperature and the recycle of the scrap. The result showed that, the influence of injection molding temperature on various properties of Cu/LDPE composites was quite complex, and 170℃was selected as the best injection molding temperature by comprehensive consideration. The properties of Cu/LDPE composites still kept stable after several times of repeating process, which indicated that repeating process wouldn’t reduce the mechanical property and cupric releasing property of material. Therefore, the recycle of scrap is feasible in practical production of IUDs.In the exploratory investigation of improving the surface hydrophilicity of Cu/LDPE composites, it was found that the contact angle of composites sharply decreased after UV irradiation, which suggested that UV irradiation can be used to improve the surface hydrophilicity of composites. Besides, as a commonly used sterilization method for medical devices, UV irradiation can also be used in the sterilization of the novel IUDs. In a word, UV irradiation is a potential post-treatment method for the novel composite IUDs.

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