The best choice of sterilization methods for medic

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Correct selection of sterilization methods for medical plastics PVC and PS

nowadays, medical plastics are widely used in the sterile medical device industry. Different products produced by enterprises determine different sterilization methods: to select the correct sterilization method, necessary scientific demonstration should be carried out to ensure the adaptability of the sterilization method of their products

at present, some medical device enterprises have not analyzed in detail the important link of "sterilization process development" in the requirements for development, validation and routine control of sterilization process of medical devices

at present, most of the plastic products of sterile medical device enterprises are sterilized with ethylene oxide. Manual valve, servo valve or proportional valve are often used as control elements to control. Ignoring the adaptability of sterilization methods leads to changes in the chemical properties of certain special products or exceeding certain performance requirements, which will cause great losses and other disharmonious factors to society, enterprises, families and individuals

we know that the conventional sterilization methods generally include damp heat, dry heat, radiation, gas, filtration sterilization and other sterilization methods. The sterilization mechanism of these sterilization methods and their impact on the characteristics of product materials should be thoroughly understood to ensure the adaptability of this sterilization method, so as to avoid some major accidents. For example: PVC and PS

1) sterile medical instruments made of PVC PVC

can not be sterilized by damp heat, dry heat, radiation and filtration, but can only be used for gas sterilization - ethylene oxide sterilization

if damp heat or dry heat sterilization is adopted, the shape of the product will change or even be dissolved by heating; The use of radiation sterilization will cause the PVC material itself to undergo a chemical reaction, and the PVC will release chlorine and some toxic substances; Filtration sterilization is generally used for sterilization of medicinal liquid or liquid, and it is also not suitable for PVC medical devices

ethylene oxide has almost no chemical effect on PVC, because its sterilization mechanism does not damage the product shape and material properties. However, due to ethylene oxide sterilization, the product itself should strictly control the residual amount of ethylene oxide. Although the carcinogenicity of EO is not clear, its toxicity, sensitization and impact on fertility cannot be ignored

we know that there are many factors that affect the EO residue, but the most important one is the molecular structure of the material that produces more VOC products during injection molding

2) PS polystyrene

generally speaking, this material is sterilized by radiation - γ Sterilization method of radiation

first of all, we need to have a simple understanding of some properties of PS, so that we can draw a conclusion and select the appropriate molding characteristic sterilization method

a. physics

ordinary polystyrene resin is a non-toxic, odorless, colorless transparent particle with a glass transition temperature of 80 ~ 90 ℃, which is a glassy brittle material. The product has extremely high transparency, the light transmittance can reach more than 90%, good electrical insulation and easy coloring. Good processing fluidity, rigidity and chemical corrosion resistance

the disadvantages of ordinary polystyrene are brittleness, low impact strength, stress cracking, poor heat resistance and boiling water resistance

b. chemistry

polystyrene has poor chemical stability, can be dissolved by a variety of organic solvents (such as aromatics, halogenated hydrocarbons, etc.), will be corroded by strong acids and bases, is not resistant to grease, and is easy to change color after exposure to ultraviolet light

the above properties determine that PS cannot be used for damp heat and dry heat sterilization, otherwise the product will soften and deform; Nor can it be used for filtration sterilization

what about gas - commonly used EO sterilization? As we all know, ethylene oxide is an organic substance with very real chemical properties. It is also known as ethylene oxide. It is the simplest cyclic ether

ethers are also common organic solvents, such as ether, propylene oxide, etc. Ethylene oxide has a certain solubility in polystyrene. Although EOG is used for sterilization, it is difficult to meet the requirements of passing time, ventilation and other factors, even for half a year or more

and radiation sterilization - γ Radiation does not damage PS raw material and its products, nor does it generate other toxic substances. It is the main sterilization method for food packaging and medical devices with polystyrene as raw material

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