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Medical tubes materials
Since its introduction in the 1940s, first medical tubes made of plastic as a cheaper replacement of glass and metal, this market has grown considerably. Today plastic is the basic material for the production of tubes for blood transfusions, oxygen and nutrients used in hospitals and clinics.
Plastic tubes are used in various fields of medicine and are essential for many modern medical procedures. Examples of such applications include vascular access catheters and tubes for biopsy (biopsy specimens) and holders for a stent implanted in the artery of the heart.
Recent developments in the medical tubes include special formulations having a unique combination of desired properties, including strength, flexibility, high gas impermeability, lubricity. Coextrusion technology advances contribute to the development of the production of plastic pipes with such unique properties. The rapid spread of minimally invasive surgery has become a major driving force behind the emergence of new materials and designs plastic tubes.
Requirements and Materials
For medical use in plastic tubes must have at least one of the following properties: insensitivity to biological tissues and secretions, elasticity, strength, resistance to heat and chemicals used in the sterilization of transparency. They must also be resistant to leaching or other plasticizers are added to the reinforcing chemicals. Two additional requirements are ease of manufacturing and low cost, especially in relation to mass application.
Polyvinyl chloride (PVC), which is an optimal combination of performance and cost, in terms of consumption is the most widely used plastic material for medical tubing. Thermoplastic elastomers, nylon, silicones, fluoropolymers, and polyetheretherketone (PEEK) also find their particular use in systems of pipes. Polypropylene, high impact polystyrene and polycarbonates also be used as materials for medical tubes. The performance of the plastics material tubing can often be enhanced by the additives and coextrusion with other polymers.
Polyvinyl chloride (PVC) in many ways is an ideal material for medical tubing. It is also widely used in other medical applications, including blood bags, dialysis equipment, oxygen masks, laboratory equipment and packaging equipment. PVC - inexpensive, easy to handle, durable and transparent material. It is manufactured in solid, soft or any intermediate form. It connects easily to almost any other plastic connector - a quality that is not true of all plastics used for medical tubing. PVC can withstand high temperatures and aggressive chemicals used for sterilization. However, despite its strength, PVC is not suitable for use at high pressure.
Perhaps the biggest obstacle to the use of PVC is diethylhexylphthalate plasticizer (DEHP), which is often found in PVC. Regulators in Europe and North America have expressed concerns about the possible adverse health effects of this additive leaching. Industry officials insist that DEHP is a safe material and still not cause any diseases associated with leaching. To resolve such doubts, some vendors offer plastic materials PVC composition excluding DEHP and other phthalate additives.
As a result, radiation sterilization PVC pipe can be colorless, but some formulators already offer products PVC, resistant to this trend.
PVC pipe often used in large disposable systems where particularly appreciated their low cost and high transparency. Such administration includes intravenous nutrient solutions or blood. Another important application of PVC pipes and tubes are catheters for dialysis.
Polyethylene has some specific advantages for medical tubing. It is 30% lighter PVC, is extremely resistant to chemicals and is competitive on cost. In particular, high density polyethylene (HDPE) has a low coefficient of friction, which determines its use in dispensers tubular wire catheters, angioplasty. HDPE High lubricity makes it extremely suitable for packaging other tubular components such as catheters, which can be easily removable from the package.
On the other hand, polyethylene has no elasticity such as PVC, and also capable of easily contact with solvents. Furthermore, the polyethylene is not so clear as PVC, however, it is less suitable when necessary visual inspection of fluids in the tubes.
Thermoplastic elastomers (TPE)
Thermoplastic elastomers of different polymer composition also play an important role in the production of medical tubing, usually with the need to provide specific properties. Some varieties TPE tubing marketed as substitutes for PVC without plasticizers, others are sold as substitutes for natural rubber latex. (Latex can cause allergic reactions in patients and health care workers). Standard TEP used for medical tubing include styrenic block copolymers, thermoplastic polyolefins, thermoplastic polyurethanes and thermoplastic copolyesters.
TEP polyolefin can be made to play the useful properties of PVC pipe-products. However, their cost of PVC is much higher, so they are rarely used in mass application.
Thermoplastic polyurethanes (TPU) exhibit a high level of transparency, tensile strength and tear resistance, chemical resistance and wear. But TPU materials are very expensive, so they tend to be used in special cases only small diameters and complex configurations lumens. TPU freely filled rentgenonepronitsaemymi additives that allows you to track their location in the body using X-rays.
Fluoropolymers are characterized by high lubricity, tensile strength and excellent resistance to chemical attack. However, they are difficult to bind with other plastics, and exhibit a low resistance to kinking. Medical tubing extrusion fluoropolymer requires technologists high degree of professionalism. Fluoropolymers typically used when necessary tight tolerance. Pipe use of these materials include catheters and intravenous catheters for angioplasty and angiography. Expanding fluoropolymer tubes are often used to hold the stent prior to implantation in the heart arteries.
Silicones are highly biocompatible. They are also very flexible, have a high degree of tensile strength and tear, hardness thereof ranges from 5 to 80 Shore A. Silicone materials are also resistant to chemicals, solvents and temperature extremes. As fluororesins, silicone materials are expensive, so they are used only when they need to use high performance. Medical use of silicone tubing includes drainage tubes, peristaltic pumps, pumping blood and fluid, dialysis equipment. You can find more information on the subject here: http://siliconemolding.livejournal.com/1057.html
Tubes made from polyamides exhibit many useful features of these materials, including tensile strength, impact strength, resistance to kinking. The most significant feature of polyamide tubes is high tensile strength under internal pressure. Due to this, they are the preferred material for the cylinder used in angioplasty. Catheters of polyamides can reach very small dimensions, while maintaining the strength that allows easy and secure them to pass through through arteries in the process of angiography. Although polyamides are in the upper price range, this factor is not taken into account in their specialized applications.
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