Materials

Polyethylene(PE) 

PE’s are among the most versatile plastics used in the medical industry. The PE family consists of different grades, each with distinct properties, processing characteristics and applications- HDPE, LDPE, LLDPE and VLDPE. These PE’s are different in properties and their applications in medical field. All the PE’s are compatible with radiation sterilization, an important feature for many medical applications. 

• LDPE: Packaging films, wound covering films, urine bags, examination gloves, catheter tracheal protheses 

• HDPE, MDPE: Blood filters, reconstruction of joint syringes, splints, bone fracture treatment, I.V.fluid bottles 

• UHMHDPE: Joint replacement prosthess: The diverse uses of lot-controlled UHMW-PE range from standard wear applications to implantable products. Biocompatibility, self-lubrication, and wear resistance are among the major requirements of articulating surfaces made from UHMW-PE. The biological response to UHMW in soft tissue and bone has been well characterized by a history of clinical use. 

Polypropylene(PP) 

PP with unique combination properties such as strength, ease of conversion, cleanliness, sterilisability, biocompatibility, easy recylability and low cost. PP is constantly growing in popularity. Numerous devices formerly made of glass and other materials are now being converted to PP. PP is easily recycled and disposed of without producing any harmful emissions even during incineration. 

Heat Stabilized (HS) Polypropylene sheet provides all of the outstanding properties found in standard polypropylene, but has been subjected to a special heat-stabilizing process. As a result, HS is able to withstand higher service temperatures with less water absorption than standard polypropylene. Recommended sterilization techniques include steam autoclaving and cold sterilization. This trend is expected to continue and accelerate health care reform. Some of the PP based devices are: 

Polystyrene(PS) 

Known primarily for its clarity and good electrical properties, polystyrene is frequently used in dosimetry applications where water is the recommended medium of choice. The electron composition of polystyrene is almost the same as water, and several of its physical parameters needed for dose measurement are well established. Using a polystyrene phantom, one can determine the dosage necessary to irradiate a tumor in a patient. 

Acrylonitrile-butadiene-Styrene(ABS) 

ABS is a general purpose amorphous thermoplastic, providing good impact strength, toughness, stiffness, and good chemical resistance. ABS is easily machined and is cost effective. 

Polyesters and copolyesters 

Copolyesters and polyester alloys with other polymers posses many characteristics which make them useful in the manufacture of medical device. Among these characteristics are resistance to property loss as a result of gamma sterilization and expose to many chemicals. These materials found applications in intravenous line components, respiratory devices and catheter systems. 

Recently these polymers have been prominently used for the blunt cannulae of needle free injection devices designed to reduce needle stick injuries and limit the risk of infection among health care products. PET is now widely used for blood collection tubes, specialty syringes, irrigation and wound drainage systems etc. 

Acetal copolymer 

Acetal Copolymer is a well-recognized engineering thermoplastic which is widely used in many medical applications. Acetals may be steam autoclaved and are easily machined. 

Polycarbonate(PC) 

Some medical instruments or containers require glass-like transparency and excellent impact resistance. With these material parameters, Polycarbonate is sometimes the only suitable material, especially, where components must be machined to close tolerances. 

Thermoplastic Polyurethane(TPU) 

Polyurethanes meet the requirements and have gained widespread use, for medical tubing. . Thermoplastic polyurethane allows reduction in gauge thickness of a medical tube or catheter while maintaining strength and properties. The TPUs can withstand 4 times as much of radiation as many other plastics. TPUs are having better burst strength than many other plastics in tubings. 

Thermoplastic elastomers(TPE) 

Thermoplastic elastomers are materials with processability like thermoplastics and performance like like thermosett rubber. These characteristics has lead to increased use of of thermoplastic elastomers in the medical industry. A major advantage of TPE over thermosett rubber is its cleanliness and biocompatibility . TPEs are available in opaque , translucent or colorable grades with warm feel characteristics. TPEs can be sterilized by ethylene oxide, steam autoclaving and gamma radiation. 

Fluoro polymers 

Fluoropolymers are very popular materials for medical tubings especially in catheter applications because of their unique characteristics. Specifically these are slippery, smooth surface resins which are generally stiff in nature. Fluoroolymers enter the body easily, slipping through incisions and avoiding blood clots and other biomaterials form agglomerating and sticking to the invasive device. Catheters and drainage tubes, coating for suture, membrane for artificial lungs, cannulae and artificial bone joints 

Polyetherimide 

Because of its superior physical properties and its ability to withstand a wide spectrum of sterilization methods, Polyetherimide is often specified as the material of choice in demanding reusable medical device applications. 

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