Properties, monographs of general purpose TPE

Between thermoplastics, which are easy to process but have limited elastic properties, and elastomers, which have remarkable elastic properties but are more complex to process, intermediate materials have appeared: thermoplastic elastomers (TPE). These are a relatively recent family of materials (the concept first appeared in the 1960s) and, thanks to their heterogeneous structure made up of flexible and rigid domains, they are halfway between rubbers or elastomers, which are irreversibly cross-linked to give them elasticity and flexibility, and thermoplastics, which give them ease of processing.

TPEs offer a combination of special properties:

• elasticity (reversible deformation under stress), limited to a moderate temperature range below the softening temperatures of rigid domains;

• reversible thermoplasticity (irreversible deformation under stress), flexibility or rigidity ;

• easy processing of thermoplastics and elimination of the vulcanization step;

• easy recycling of thermoplastic waste.

In fact, there is no definite boundary between thermoplastics and TPEs, but rather continuity. On the other hand, if the properties of TPEs come close to those of elastomers, there is discontinuity in terms of morphologies and processing.

Thermoplastic elastomers include both products with common properties (e.g. SBS and TPO) and those with more specific technical characteristics (e.g. COPE and PEBA). More recently, new families have emerged with one or more particularly high-performance properties. These are often grouped together under the general heading of super TPEs, and are covered in the following dossier [AM 3 401] .

TPE development is still limited, but the growth rate is higher than for thermoplastics and rubber. The main advantage of VSEs for plastics manufacturers lies in the fact that their equipment (injection presses, extruders, etc.) and their experience in processing thermoplastics give them access to part of the elastomer market.

TPEs can be co-processed with conventional thermoplastics, expanding the possibilities for integrating functions to reduce costs.

The rates and percentages given in this text are, unless otherwise indicated, by mass.