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What is a TPE?

Thermoplastic Elastomers are generally low modulus, flexible materials that can be stretched repeatedly to at least twice their original length at room temperature with an ability to return to their approximate original length when stress is released. The grandfather materials with this property are thermoset rubbers, but many families of injection-moldable thermoplastic elastomers (TPEs) are replacing traditional rubbers. In addition to use in their basic form, TPEs are widely used to modify the properties of rigid thermoplastics, usually improving impact strength. This is quite common for sheet goods and general molding TPEs.

Types of TPEs

Until as recently as 1996, the six primary TPE types could be categorized into two generic classes, block copolymers (styrenics, copolyesters, polyurethanes and polyamides) or thermoplastic/elastomer blends & alloys (thermoplastic polyolefins and thermoplastic vulcanizates).

In addition to these TPEs, two new technologies have emerged. They are the metallocene-catalyzed polyolefin plastomers & elastomers, and reactor-made thermoplastic polyolefin elastomers.

Traditional TPE types are known as two-phase systems. Essentially, a hard thermoplastic phase is coupled mechanically or chemically with a soft elastomer phase, resulting in a TPE that has the combined properties of the two phases.

Traditional TPE Classes

    Styrenics (S-TPE's)
    Copolyesters (COPE's)
    Polyurethanes (TPU's)
    Polyamides (PEBA's)
    Polyolefin Blends (TPO's)
    Polyolefin Alloys (TPV's)

New TPE Entrants

    Reactor TPO's (R-TPO's)
    Polyolefin Plastomers (POP's)
    Polyolefin Elastomers (POE's)

The new POPs and POEs are essentially very low molecular weight, linear low density polyethylenes (VLMW-LLDPE). The results of advancements in polymerization catalyst technology, these materials were originally developed to improve flexible packaging film characteristics. Recently, these more flexible polyethylenes have seen use as low-cost rubber replacements for some non-demanding molded goods applications. These primarily include products that will not be exposed to extremes in temperatures, pressures, loads or stress environments. In molded goods, these new materials are being used where a more or less limited degree of flexibility or tactile feel is desired. Note that they are not true elastomers.

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