What Is a Thermoplastic Elastomer?
Thermoplastic elastomer is a polymeric material that exhibits rubber-like elasticity at room temperature while becoming fluid at high temperatures. Like thermoplastics, they can be easily molded when heated, making them an intermediate material between synthetic rubber and thermoplastic resin.
The elasticity of elastomers is due to the cross-linking of polymer chains, enabling them to return to their original shape. Thermoplastic elastomers are widely used due to their excellent moldability and reusability.
Uses for Thermoplastic Elastomers
Thermoplastic elastomers are used in various applications due to their elasticity and moldability. They are used in household goods like mobile phone cases and kitchenware, automotive parts, power tools, and other products requiring abrasion resistance and elasticity. Their lightweight and colorability also contribute to their versatility. In the medical field, they are used in rubber gloves as they do not contain allergens found in natural and synthetic rubbers.
Principle of Thermoplastic Elastomer
1. Principle of Elasticity
Thermoplastic elastomers consist of long polymer chains with hard and soft segments. The hard segments form intermolecular cross-links through hydrogen bonds, creating a mesh structure that acts as pseudo-crosslinks. Soft segments allow for elasticity due to their free movement.
In contrast to synthetic rubbers, where cross-linking is through covalent bonds, thermoplastic elastomers use hydrogen bonding for cross-linking.
2. Principle of Thermoplasticity
The hydrogen bonds in thermoplastic elastomers break at high temperatures, dissolving the cross-linked structure and turning the material fluid. Upon cooling, the hydrogen bonds reform, restoring the cross-links and elasticity. Synthetic rubbers, on the other hand, do not regain their elasticity after heating due to permanent covalent bond dissociation.
Types of Thermoplastic Elastomers
Various types of thermoplastic elastomers include styrenics, olefins, urethanes, esters, and amides.
1. Styrene-Based
Styrene-based thermoplastic elastomers have polystyrene hard segments and polybutadiene soft segments, commonly used in products due to their lightweight and natural rubber-like feel.
2. Olefin-Based (TPO)
Olefin-based (TPO) elastomers are copolymers of ethylene, propylene, and a diene component.
3. Urethane (TPU)
TPU, formed by the reaction of polyol and isocyanate, is used in textiles and some automotive parts for its high elongation and strength.
4. Ester-Based (TPC)
Ester-based (TPC) elastomers, comprising polyester hard segments and amorphous soft segments, are known for their high impact resistance and excellent heat, chemical, and aging resistance.
5. Amide-Based (TPA)
Amide-based (TPA) elastomers, containing polyester or polyether soft segments and polyamide hard segments, offer excellent abrasion and impact resistance, flexibility at low temperatures, and weather and chemical resistance.