As a leader in polymer compounds used for minimally invasive devices, Foster has developed a core competency in the custom compounding of thermoplastic elastomers. Thermoplastic elastomers are unique synthetic compounds that combine some of the properties of rubber with the processing advantages of thermoplastics. They consist of a number of families, including:
TPO'S - polyolefin based elastomers, such as (EPDM) Ethylene Propylene Diene Modified Rubber, (EPR) Ethylene Propylene Rubber, (FPO) Flexible Polyolefin, and (POE) Polyolefin Elastomer
SBC - styrenic block copolymer elastomers, such as SBS, SEBS and SIS
TPV - consists of elastomers where the rubber portion is fully cured or partially cured.
TPU - Polyether or polyester soft block segments coupled to aromatic or aliphatic isocyanate hard blocks
COPE - Polyether soft block segments coupled to aromatic polyester hard blocks
PEBA - copolyamide type of elastomers, such as polyether block amide
Like rubbers, the key properties of thermoplastic elastomers are hardness and flexibility. TPEs offer properties bridging the gap between rigid plastics and soft rubbers, like latex or silicone. The families overlap each other in these characteristics. The TPU'S, COPE'S and the PEBA'S offer the hardest and stiffest grades available, because of this they are sometimes referred to as the engineering thermoplastic elastomers.
Out of all the available families of TPEs, polyurethane (TPU) and polyether block amide (PEBA) have the property balance to be successfully utilized in demanding medical applications such as catheter tubing, balloons for catheters, films for wound dressings, surgical drapes, storage bags, strain reliefs, etc. These materials offer a good balance of biocompatibility, tensile strength, toughness, elongation, kink-resistance, hydrolysis-resistance and thermoplastic processability.
Medical design engineers are constantly pushing the limits of these TPEs and are always looking for ways to achieve even higher performance than what is currently available. Engineers also want to narrow the specification tolerances, enabling their use in micro-precision molding and thin wall extrusion processes.