A Comprehensive Comparison of Vinyl Ester vs. Polyester Resins

A Comprehensive Comparison of Vinyl Ester vs. Polyester Resins


There are three main types of resins used today for carbon fibers, fiberglass, and aramid (Kevlar). These are epoxy, vinyl and polyester resins. Each one has different characteristics and associated costs. We briefly discuss each of these resins below.

Be aware that all resins and solids have safety concerns. Research the products you want to use, read all the manufacturer’s safety information, and follow their recommendations.

Polyester resin comes in the form of a sticky honey-like liquid and is a contact product that requires no pressure to process. The resin hardens in a matter of hours and gives a very resistant finish. It can be sanded and polished to a bright, transparent finish.

Polyester resins are easy to use and are considered the cheapest of all resins. However, resin products are not resistant to UV rays and can easily break if dropped.

Vinyl ester resins are an intermediate between the polyester structure and the epoxy ends at the particles’ ends.

Vinyl Ester is formulated for maximum resistance to wear and tear from most fuels, fumes, and chemicals. It is heat resistant and mixes for long life. It is characterized by excellent impact resistance and high tensile elongation. It has a low viscosity, making it easy to pour and well suited for vacuum infusion.And it often use in bọc phủ composite

The differences

These unsaturated resins are combined with other chemicals, sometimes called solids or catalysts. This changes the molecular structure, and the resulting compound hardens and generates heat. Methyl ethyl ketone peroxide (“MEKP”) is one of these “solidifiers.”

Vinyl ester resins are made by reacting (“esterifying”) between the epoxy resin and the unsaturated monocarboxylic acid. It consists mainly of a polyester resin base reinforced with epoxy particles in the molecular chain’s backbone. Phenyl esters are also used as peroxides (like MEKP) for processing.

Advantages and disadvantages

Vinyl esters are halfway between polyester and epoxy before adding styrene. Thinning affects workability and strength – thinning reduces strength but makes brushing or spraying easier.

Vinyl esters are more ductile than polyester. This allows them to better absorb shocks without taking damage. They are also less likely to show stress cracks.

Vinyl ester has fewer vacancies in its molecular chain. This makes them more resistant to the ingress of water (“hydrolysis”), leading to osmotic ulcers. Vinyl esters shrink less when cured, which means the pre-release of the mold sheets is less critical. Vinyl esters are more ductile than polyester. This allows them to better absorb shocks without taking damage. They are also less likely to show stress cracks.

The crosslinking of vinyl esters is superior to that of polyesters. This means that vinyl esters bind to the base material more effectively than polyester, and disassembly is not a problem.

Vinyl is expensive compared to polyester because careful calculations must assess the cost implications of a large construction project, such as a luxury yacht. This is because relative strength must be taken into account – you can use a lower phenyl ester to achieve specific stability.

Both resins are subject to “gypsum,” the dissolution of UV rays on the surface, provided that no additive is incorporated into the mix.

Which to use

Despite the vinyl ester (regardless of its cost), polyester still plays an essential role in composites.

If water is likely to be exposed for extended periods (for example, a boat hull or water tank), using polyester for bulk construction with a vinyl roof barrier can significantly reduce water ingress without adding much cost.

When it is essential to improve durability and impact resistance, vinyl esters beat polyester; again, the structure can be modified so that vinyl esters are used in areas with higher impact potential. However, these are relative resins and can be higher (and more expensive) resins or other compounds.

Common uses

Polyester vinyl esters are widely used for several similar uses. However, when the physical properties of the vinyl ester are more important than cost, the vinyl ester takes the lead:

Transportation: spare parts for cars and other road transport vehicles

Buildings and infrastructure: building facades and bridge reinforcements

Military/aerospace applications


Before making any decisions, you need to consider the shelf-life requirements and weigh the cost carefully. On the other hand, both can work well with the application.

Which lamination system is best for you and your family, and which one you want to build their trust and investment in because it is a long-term purchase. In today’s nautical industry, there is no more for less, and there is little for less.

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