Composites Explained

Thermoset vs. Thermoplastic Polymer Matrix

The use of fiber-reinforced polymer (FRP) composites is becoming increasingly commonplace across a wide range of industries and applications. However, the combinations of materials that make up the composites themselves can be as varied as the end-uses. From engineered, man-made, or natural fiber reinforcements to thermoset or thermoplastic resins, there is a lot to consider when selecting a composite material.

Let’s take a closer look at the differences between the thermoset and thermoplastic polymers that play a critical role in determining the performance characteristics of the final composite product.

A thermoset is a cross-linked polymer that cannot be reshaped after it’s formed, cured, and cooled. Think of an egg that, once cooked, cannot return to its original state.

Common thermoset formulations include polyester, vinyl ester, epoxy and polyurethane (PU).


  • High temperature resistance
  • Creep resistance
  • Low viscosity
  • Paintability
  • Long history in composite technology
  • Excellent fatigue resistance

A thermoplastic is not cross-linked, so it can be re-melted and re-formed, much like an ice cube that can melt and re-freeze.

Thermoplastics used in making composites range from polypropylene (PP), nylon (PA) and polycarbonate (PC) to polyester, polyphenylene sulfide (PPS), and polyetheretherketone (PEEK).


  • Potential for recyclability
  • Enhanced toughness
  • Chemical resistance
  • Noise and vibration damping
  • Lower density
  • Final shaping possible
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