How to choose resin for making carbon fiber composites

Composite materials are all combined with reinforcing fibers and a plastic material. The role of resin in composite materials is crucial. The choice of resin determines a series of characteristic process parameters, some mechanical properties and functionality (thermal properties, flammability, Environmental resistance, etc.), resin properties are also a key factor in understanding the mechanical properties of composite materials. When the resin is selected, a series of processes and properties that determine the composite material are naturally determined.

At present, most of the application and performance of carbon fiber requires the selection of resin as the carrier. The performance of the resin greatly affects the overall performance of the composite material. Different application environments and requirements need to be formulated with different resins. The selected resin Can have a significant impact on your finished project. The choice of molding resin can vary depending on the compatibility of the fabric, the conditions of use, and the desired properties of the finished part. When making carbon fiber composites, there are generally three types of thermoset resins to consider: epoxy, vinyl ester, and polyester. Below is a broad overview of all three, including their characteristics, and what they should be used for.

Epoxy resin

For composite parts that require ultimate strength, manufacturers will use epoxy. In addition to improving strength properties, epoxy resins are often preferred over polyesters and vinylesters for dimensional stability and increased bonding with other materials.

Advantage: Epoxy resin, high strength properties, can be used in vacuum infusion applications, easy handling, medium viscosity

Shortcoming: Cannot be used on chopped strand mat, is not UV stabilized, must be paired with a topcoat when exposed to UV light

Polyester resin

Polyester resins are the most widely used resins in the composites industry. Polyester resins are less expensive, have some corrosion resistance, and are more forgiving than epoxy resins. The majority of all fiberglass components are constructed with polyester resins because they are easy to use, fast cure, and withstand temperature and catalyst extremes. Fiber Glast comes with two different types of polyester resins, each with their own benefits and uses.

Advantage: Easy to handle, fast wet out, high thixotropic index (product will not run on vertical surfaces)

Shortcoming: Lower physical properties compared to more expensive resins

Vinyl ester resin

Vinyl ester resins are considered a blend of polyester and epoxy resins - meaning their handling properties, performance and price often fall between the other two. Notably, of the three, vinyl ester resins will provide the highest corrosion resistance, temperature resistance, and elongation (toughness). Therefore, they are usually used when high durability, thermal stability and corrosion resistance are required.

Advantage: Vinyl ester resin, Very stable,  corrosion resistant, heat resistant

Shortcoming: Short shelf life (3 months)