Medical applications sterilization

The launch of new resins being rare, progress on materials intended for medical applications is by way of formulation, alloys and modifications of existing resins. Thus, new radiation-stable polypropylene grades are available for the manufacture of cups, boxes, baskets, mixers, etc. that are radiation sterilized. And polyesters with better environmental stress cracking resistance are extending their potenti in the area of medical testing. 

In addition to the functional tests common to any application, the TPEs that are proposed for medical applications must satisfy certain specific tests of biocompatibility and aptitude for sterilization. 

Polyarylsulfones offer materials with good thermal-oxidative stability, solvent resistance, creep resistance, and good hydrolytic stability. Their low flammability and smoke evolution encourage their use in aircraft and transportation applications. They hold up to repeated steam sterilization cycles and are used in a wide variety of medical applications such as life support parts, autoclavable tray systems, and surgical and laboratory equipment. Blow-molded products include suction bottles, surgical hollow shapes, and tissue culture bottles. PPS has a number of automotive uses including as an injection-molded fuel line coimector and as part of the fuel filter system. 

Choosing an adhesive for a medical application follows the same process as choosing an adhesive for any other purpose. Criteria include the particular substrates to be joined, strength requirements, type of loading, impact resistance, temperature resistance, fluid resistance, and processing requirements. However, the function of many medical devices requires at least two other important criteria resistance to sterilization and low toxicity. As a result, several important standards and regulations have been developed in the industry. 

Possibility of joining hydrogel formation and sterilization in one technological step, which is advantageous for hydrogels in medical applications... 

Major polymer applications aircraft interiors, multipin connectors, coil bobbins, integrated circuits sockets, fiber optics connectors, dip switches, automotive fuses, printed circuit boards, transformer wire coatings, microwave cookware, sight glasses, membranes, medical applications (due to the resistance to different methods of sterilization), coatings... 

Major polymer applications tubing, in medical applications which require resistance to hot water and sterilization, microwave cookware, printed circuit boards... 

One of the most important performance criteria for medical applications is that of autoclaving. This is a common method to sterilize instruments and devices that uses a combination of high pressure and steam. In an aggressive cyclic environment such as this, retention of impact properties and optical properties is important. Another essential sterilization technology that is less severe than autoclaving is the use of ethylene oxide, against which blends and alloys must display chemical resistance. 

Besides sterilization, chemical resistance is generally an important attribute that blends and alloys in medical applications must possess. Key chemical agents that must be evaluated include saline solution, isopropyl alcohol, ethyl alcohol, betadyne, chlorine bleach, and lipids. 

Blon elastomer Is an Implantable material suitable for a variety of medical applications. The material exhibits excellent blocom-patlblllty. Is resistant to oxidation, and Is stable to Irradiation at sterilization dose levels. Major advantages are Its high... 

Medical applications of PP such as disposable syringes, hospital trays, and labware are contingent on sterilizability, either autoclaving or radiation. Disposable syringes that are sterilized by radiation require special formulations to prevent discoloration (yellowing) or brittleness as a consequence of degradation and cross-linking. 

Sterilizability is of essential importance when the pol5mier is used in medical applications. Steam sterilization is preferred over chemical sterilization and radiation sterilization. Steam sterilization consists of a treatment of the membrane with superheated steam of >110°C for 30 min. Steam sterilizable membranes include poly(ether imide), PES and poly-(vinylidene fluoride). 

Sterilization and radiation resistance 16 Growing use of POs in medical applications, radiation-intensive sterilization treatments Better antioxidants and stabilization against radiation... 

Vitamin E has also been used as an AO to provide postradiation sterilization stability for body-contact medical applications (e.g., see Case 3.4 at the end of this chapter). 

Plastics for medical applications will likely to grow in use, especially for pouches, bottles, trays, wrap, syringes, and other sterile closures or packaging. The aimual growth of medical packaging in the United States has been estimated at 6%, and POs are particularly positioned as the materials of choice for the lower-cost applications [16-1]. 

Polymer blends could be irradiated for the same purpose as polymers. For example, polymer devices for medical applications have been sterilized by irradiation for many years. Irradiation could also be used to obtain a polymer material suitable to foam by modifying its structural parameters (macromolecular mass, branch content). " For such an application, even if the irradiation of polymer blends is more complex than the irradiation of a pure polymer, the main objectives are the same in both cases. Thus, the following part will consider only the specific applications of irradiated polymer blends. 

The glue-like phase between the concentric cylinders of pestle and tube are maintained in the phase-separated state and exposed to 20 Mrad of y-irradiation from a cobalt-60 source. (Alternatively, chemical cross-linking can occur with a suitable reactive chemical either without or with functional side chains, or cross-linking can occur enzymatically with introduction of appropriate sequences.) One of the advantages of y-irradiation is sterilization and biocompatibility for medical applications. 

---