Polymer Basics for High Temperature Thermoplastics
High temperature thermoplastics are melt-processable plastics with extreme heat resistance. They are also referred to as high performance or engineering polymers due to their high heat resistance of over 200°C. Other key characteristics of these materials include outstanding strength, long-term durability, and biocompatibility.
High temperature thermoplastics are more adaptable than standard plastics due to their better mechanical properties, higher heat resistance, and higher chemical stability. They can also endure multiple cycles and doses of all radiation types and have an outstanding ability to be molded into parts with tight tolerance. High-temperature thermoplastics currently enjoy a rapidly growing segment of the plastics market, including in various medical applications.
Characteristics and Properties of High Temperature Thermoplastics
High temperature thermoplastics boast continuous operating temperatures of over 200°C. Their high-temperature resistance provides many valuable characteristics over other materials such as metal. These include:
- Adaptability to property modifications for specific applications
- Adaptability to high volume production processes
- Increased design flexibility
- Excellent chemical and corrosion resistance
- Adjustability conductivity or high electrical and thermal insulation
- Excellent noise and vibration damping
- A low density that eases installation and portability
High temperature thermoplastics are made from raw materials such as colorants, polymer resins, and additives, based on the formulation needed. The raw materials are blended to the required standard that guarantees uniformity and consistency throughout the batches. The resulting product is then heated and pressed through an extrusion die and drawn into a sheet before being passed through additional roller sets to achieve the desired thickness and surface texture.
As the sheet travels down the line, it is cooled and cut to size. During the manufacturing process, rigid aromatic rings are introduced in aliphatic groups, giving the thermoplastic its high-temperature resistance characteristics. The aromatic rings restrict the movement of the backbone chain when the material is subjected to high heat.
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Common Uses in Medical Devices and Life Sciences
High temperature thermoplastics enjoy excellent prospects in the medical devices market. Plastic continues to replace standard materials for medical devices due to its greater design flexibility and cost-effective characteristics. Some of the popular high-temperature thermoplastics employed in the medical field applications include:
- Polyetheretherketone (PEEK) is commonly used as a replacement for glass, stainless steel, and other metals in several medical applications such as dialyzers, dental instruments, handles on syringes, endoscopes, and sterile boxes that hold root canal files.
- Liquid Crystal Polymers (LCP) is used to replace metal in medical device applications for microsystem technology and minimally invasive surgery.
- Polysulfones (PSU) and polyethersulfones (PES) are commonly used to manufacture parts and membranes of dialyzers, surgical theater luminaries, sterilizing boxes, secretion bottles, reusable syringes, and infusion equipment.
- Polyetherimide (PEI) is used for a myriad of disposable and reusable medical devices.
- Polyphenylsulfone (PPS) is often used in the development of sterilizable containers.
The Best Method of Sterilization
The preferred sterilization methods for high-temperature thermoplastics include irradiation gamma (gamma/e-beam), ethylene oxide (ETO), and steam autoclaving.
However, the methods' effectiveness and suitability are dependent on each high-temperature thermoplastic's specific properties. Most high temperature thermoplastics can withstand ETO exposure without displaying any significant changes to their color or properties. It should be noted that the devices undergoing ETO sterilization must have gas permeable packaging to allow the gas to go through it so that the device is effectively sterilized.