Vinyl Ester Resins

Vinyl esters were developed to combine the advantages of epoxy resins with the better handling/faster cure times typical of polyester resins. They are typically reinforced with glass fibres or, more commonly now, carbon fibres to produce a material which is stronger than polyester resin and more resilient than epoxy. It provides excellent resistance to water, organic solvents and alkalis, but less resistance to acids than polyester.

Vinyl esters are flexible, making them well suited to parts which need to withstand impact and repeated flexing without developing cracks. The surface quality that can be achieved is not as good as with polyesters. The built in-toughness of vinyl esters makes smooth surfaces hard to accomplish, and the double bonded nature creates shrinkage during the curing process.


  • Vinyl esters offer mechanical toughness and excellent corrosion resistance.
  • Stronger than polyesters
  • More resilient than epoxy


  • More expensive than polyester
  • Surface quality is not as good as polyester

Processing technologies

The best processes for producing parts with this material are:

  • Open moulding
  • Resin transfer moulding (RTM)
  • Sheet moulding compounds (SMC)

BFG International’s experienced designers and engineers select the optimal process in each case based on variables such as the client’s tooling budget, dimensional tolerance and physical properties of the parts, and production volume.

Techinical details*
Tensile strength15,000psi
Flexural strength30,000psi
Density1.80 grams/cc formulated
Modulusgreater than 1.5MMpsi
Viscosityapprox. 500 centipoise when cut in styrene (the standard monomer)

* For typical 28% glass reinforcement

Contact us to discuss your project with one of our experts in the field.