Thermoplastics, Elastomers and Thermosets

  |  , , ,


What material is best for my project?


Thermoplastics, elastomers, and thermosets are three distinct classes of polymers, each with unique properties and characteristics.  How do you know which one is best for your project?


  • Definition: Thermoplastics are polymers that become pliable or moldable when heated and solidify upon cooling. This process can be repeated multiple times without significant degradation.
  • Behavior: They soften when heated and can be reshaped or remolded, making them highly versatilefor manufacturing processes like injection molding, extrusion, and 3D printing.
  • Properties:
    • They typically have good impact resistance and mechanical strength, depending on the specific type.
    • Examples include polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC).
    • They are recyclable and often used in a wide range of applications from packaging and consumer goods to automotive parts and medical devices.


  • Definition: Elastomers are polymers that exhibit elastic properties, meaning they can return to their original shape after deformation when the applied stress is removed.
  • Behavior: They are characterized by their ability to stretch significantly and then retract to their initial shape, due to the cross-linked polymer chains.
  • Properties:
    • They have excellent elasticity, resilience, and fatigue resistance.
    • Examples include natural rubber, silicone rubber, and polyurethane elastomers.
    • Elastomers find applications in seals, gaskets, tires, footwear, and various vibration dampening components.


  • Definition: Thermosets are polymers that undergo a chemical reaction (often called curing or cross-linking) during processing, leading to a permanently set shape.
  • Behavior: Once cured,thermosets cannot be remolded or reshaped by heating, as they undergo a chemical change that irreversibly hardens them.
  • Properties:
    • They typically have excellent dimensional stability, high temperature resistance, and chemical resistance.
    • Examples include epoxy resins, phenolic resins, and polyurethane thermosets.
    • Thermosets are commonly used in applications requiring durable and heat-resistant materials such as in electronics, aerospace, automotive parts, and in household appliances.

Key Differences:

Response to Heat:

  • Thermoplastics: Soften with heat and can be reshaped.
  • Elastomers: Can stretch and return to their original shape due to elasticity.
  • Thermosets: Hardenirreversibly with heat or chemical curing.


  • Thermoplastics: Generally recyclable.
  • Elastomers: Recycling potential varies; some can be recycled.
  • Thermosets: Difficult to recycle due to their irreversible curing process.


  • Thermoplastics: Widely used in consumer goods, packaging, and automotive industries.
  • Elastomers: Commonly found in seals, tires, and flexible components.
  • Thermosets: Used in applications requiring heat resistance and durability, such as electronics and aerospace.

Understanding these differences helps inselecting the appropriate polymer for specific engineering, manufacturing, orproduct design needs based on properties like flexibility, durability, and recyclability.

Performance Plastics, a Pexco Company, has experts in material engineering that can assist you in choosing the best material class for your project.

Fort more information on any of these materials, or how Pexco can help you with your custom project, please contact Rich Reed, Vice President of Sales – Custom, at [email protected] or visit our website at