ABSTRACT

Thermoplastic elastomers are polymers that have the physical properties of elastomers (e.g., long range, reversible extensibility) but, in contrast to conventional elastomers (rubbers), can be processed as thermoplastics (Holden, 1996; Allport, 1973; Noshay, 1977). Conventional elastomers must be covalently crosslinked into a three-dimensional network structure (e.g., via peroxide curing or sulfur vulcanization) to provide useful physical properties (Morton, 1987). Consequently, these elastomers behave as thermosetting materials and cannot be processed or reprocessed after crosslinking. Thennoplastic elastomers rely on a physical crosslinking process (i.e., intennolecular forces of attraction) to fonn a three-dimensional network structure and prevent viscoelastic flow. At sufficiently high temperatures, the physical forces of attraction fanning the network can be disrupted, which allows the polymer to soften and flow. Some of the advantages of thennoplastic elastomers are that they can be fabricated using conventional thennoplastic processes (e.g., injection molding, extrusion, and blow molding) and that the scrap can generally be recycled.