Glass-fibre reinforced polyester (Dutch “gup”) is a composite of polyester resin reinforced with glass fibre, a form of GRP. It is a thermoset, so once cured it can no longer be reshaped.
Characteristics
The material combines a plastic matrix of polyester resin with glass fibre as reinforcement, making it both light and strong. As a thermoset it stays dimensionally stable after curing and cannot be remelted. In a fire it chars and becomes brittle. It is not inherently UV-resistant: without a topcoat or gelcoat the surface discolours and weathers. Its difference from the broader term GRP (glass-reinforced plastic) lies in the matrix: here it is specifically polyester, whereas GRP may also be based on epoxy, for example.
Applications
Common processing methods include hand lamination, fibre spraying, pressing in a closed mould, and pultrusion. In construction the material is used for translucent corrugated and roof sheets, roof lights, and facade panels. Larger structures such as silos, tanks, and ducts are also made from it, thanks to its combination of strength, low weight, and chemical resistance. For durable outdoor use, a UV-resistant topcoat or gelcoat is recommended.
Related terms
- GRP
- polyester
- composite
- pultrusion
- corrugated sheet
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