Thermoplastic Elastomers (TPE)

With many of the desired physical properties of rubbers like softness, flexibility and resilience, thermoplastic elastomers (TPEs) nevertheless can be processed like ordinary thermoplastics.. While rubbers must be crosslinked in a slow and irreversible process to give useful properties, TPEs can be melt-processed reversibly by conventional molding and extrusion processes.

TPEs are often multiphase compositions in which the phases are intimately dispersed either mechanically or by block or graft copolymerization. At least one phase consists of a material that is hard at room temperature, but becomes fluid on heating. Another phase is a softer material that is rubbery at room temperature. Among the block copolymer TPEs of commercial importance are polyester elastomers of general structure (A-B)n.

In these polyester TPEs, the hard polyester segments can crystallize, giving the polymer some of the attributes of semicrystalline thermoplastics, most particularly better solvent resistance than ordinary rubbers, but also better heat resistance. Above the melting temperature of the crystalline regions, these TPEs can have low viscosity and can be molded easily in thin sections and complex structures.

Properties of thermoplastic polyester elastomers can be fine-tuned over a range by altering the ratio of hard to soft segments. This capability is effectively exploited in Ticona's range of Riteflex® polyester elastomers.