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Unsaturated polyester resin (UP)

By sensXPERT

Unsaturated polyester resin (UP)

Unsaturated polyester resin (UP)

Polymer Type: Thermoset

Key Properties

  • Good mechanical strength and rigidity
  • Good electrical insulating properties


  • Fiber-reinforced composites: Boats, body panels, pipes, tanks, construction panels.
  • Gelcoats and casting resins: Decorative surfaces, furniture, countertops, art objects.
  • Adhesives and sealants: Bonding diverse materials, sealing joints and leaks.
  • Electrical components: Insulators, housings, potting compounds.
  • Chemical processing equipment: Tanks, pipes, linings for corrosion resistance.

Additional Information

Unsaturated polyester resin (UP) is a thermosetting resin formed by the reaction of unsaturated polyester with styrene monomer and other components. The cross-linked polymer network formed during curing offers good mechanical strength, chemical resistance, and electrical insulating properties.

The versatility of UP lies in its diverse formulations. By varying the type of polyester, additives, and catalysts, one can tailor UP for specific applications. Reinforcing the resin with fibers like fiberglass significantly enhances its strength and rigidity, making it suitable for demanding structural applications.

However, UP resins also have limitations. They can be susceptible to UV degradation, requiring protection for outdoor use. They also release styrene during curing, requiring proper ventilation and safety measures. Additionally, their flammability necessitates specific considerations in certain applications.

Notes on UP:

  • Different UP types exist, each with varying properties and uses. Common types include orthophthalic, isophthalic, and vinylester resins.
  • Selecting the right UP formulation and reinforcement materials is crucial for optimal performance in specific applications.
  • Processing methods like hand layup, spray-up, and pultrusion influence the final product properties.
  • Sustainable considerations are driving advancements in bio-based UP resins and improved recycling techniques.

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