A thermoplastic is a type of plastic that can be heated, formed, and cooled into shape. An elastomer is a natural or synthetic material with elastic properties, like rubber.
Thermoplastic elastomers (TPEs) are plastics that combine those elements. They can be heated, formed, and cooled into a shape; however, they retain their rubber-like qualities after they cool.
Because they soften when heated, thermoplastic polymers can easily mold into various shapes and maintain the desired mechanical properties after cooling. Common uses for these polymers include fabricating ropes, belts, different types of containers, insulation materials, and numerous medical devices.
TPEs are made by joining two or more monomers. One of the monomers provides the hard, or crystalline, segment that functions as a thermally stable component; the other monomer develops the soft, or amorphous segment, which contributes the “rubbery” characteristic. Its physical and chemical properties can be controlled by varying the length of each hard or soft segment.
Thermoplastic Elastomers (TPE) and Thermoset Elastomers (TSE) have one very important difference. A TSE, during formation, undergoes a chemical reaction called vulcanization, where strong chemical bonds are formed. Whereas TPEs can be reheated and reshaped, a TSE, due to vulcanization, once cooled, loses its ability to be heated and reprocessed into a different shape.
According to Laurence W. McKeen, in Fatigue and Tribological Properties of Plastics and Elastomers, TPEs have two big advantages over TSEs: ease and processing speed. Other advantages are the recyclability of scrap and lower energy costs for processing.
Additionally, TPEs are molded on standard plastics-processing equipment with considerably shorter cycle times than those required for molding conventional rubbers.
In short, because of its ability to be reheated and thus recycled, TPEs are a more sustainable material than TSEs.
Medical device manufacturers use Thermoplastic Elastomers (TPEs) for applications requiring flexibility for various reasons.
TPEs are popular because of their high degree of purity, meaning a low level of extractable compounds.
According to Flexible Working: TPEs are materials of choice for medical devices, “Medical grade TPEs are made with FDA compliant raw materials and are free of phthalates and latex proteins. In addition, TPEs are inherently designed to have extremely low extractables or leachables, even when in contact with aqueous-based systems (like bodily fluids).”Medical Plastics News
Unlike vulcanized rubber, TPEs can not only be heated and molded into a shape but can also be reheated and reshaped. They process more efficiently and economically than thermoset rubber. This means that outdated, expired, or otherwise waste devices can be sterilized or recycled to reduce production costs.
Latex may cause an allergic reaction in some patients and although phthalate-free PVC compounds are available, many medical device manufacturers are looking for alternatives. Additionally, because TPEs remain flexible even at low temperatures, they have begun to replace PVC, latex, and silicone rubber in the medical industry.
According to Medical Plastics News, some applications include tubing, bags, pouches, drip chambers, masks, cushions, syringe tips, ventilator bags, luers, stoppers, gaskets, seals, and dropper bulbs.
Our Innovation Design Team will work with you to design, engineer, manufacture, and provide custom plastic molded solutions. Ask us how we can provide greater design freedom and offer a wider range of color options using our TPEs.