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The role of the matrix in a composite profile is partly to bind the reinforcement together, and partly to keep the reinforcement correctly positioned in relation to the cross section with a view to optimal utilization of the mechanical properties. The type of matrix also determines properties such as corrosion resistance, electrical insulation properties, and fire and temperature resistance.

The following three types of matrix are fundamentally well suited to the pultrusion process: polyester, epoxy and phenol.


Polyester is the most frequently used matrix as it produces a composite with good all-round properties.

Unsaturated polyester can be divided into three main groups: orthopolyester, isopolyester and vinylester. Compared with orthopolyester, isopolyester increases impact resistance, provides greater flexibility, and increases resistance to temperatures. It also increases corrosion resistance.

Vinylester has even better corrosion resistance and thermal properties. Since vinyl ester has greater elongation properties than ortho- and isopolyester, it also provides a composite with better impact resistance and improved fatigue properties.


Epoxy is used primarily for carbon-reinforced profiles, giving composites better fatigue and mechanical properties. Epoxy is more resistant to thermal influences and has better electrical properties.


Phenol is used when there are requirements to high fire resistance, temperature resistance, low smoke generation, and flame retardation when subjected to fire.


“Additives” is a general term used for agents which are added to the matrix. Depending upon their purpose, additives can be divided into three fundamental groups: price-reducing additives, process-related additives and function-related additives. While the purpose can vary, additives will always influence the corrosion resistance of profiles, as well as their mechanical and fire-technical properties.

Process-related additives 

Process-related additives are substances that have beneficial effects on the pultrusion process and on the properties and appearance of a cured profile. One example is the “low-profile additive” used to avoid excessive shrinkage during curing of profiles. The additive prevents formation of hair-line cracks in surfaces, while increasing profile resistance to corrosion and improving fatigue properties. It also gives profiles more exact geometric tolerances and lower internal stress.

Function-related additives 

Function-related additives have a beneficial effect in relation to the use of a finished profile. One example is the adding of pigments. Adding of fire retardants is another example. The latter are added to obtain self-extinguishing properties and to retard flame spread.

Of course, function-related additives can also be added in amounts so large as to degrade the mechanical properties of a profile.

See also the Fiberline Quality Codex on page 0.10-0.11 of the Fiberline Design Manual.

Price-reducing additives*

The sole function of price-reducing additives is to fill out the form of a profile, and adding such additives enables reduction of more expensive reinforcement and matrix materials. It is thus possible to reduce the price of the finished profiles accordingly. Profiles have significantly poorer mechanical properties when the amount of reinforcement is reduced. Moreover, most types of price-reducing additives also result in profiles with lower corrosion resistance and diminished resistance to most chemicals.

*Often referred to as “fillers”.

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Combining advantages

CE marking

Our products have a number of international and highly sought-after certifications, among other, within the construction, offshore and railway sectors. This is your guarantee of consistently high quality every time you buy from us and use our products.

Low weight

Fiberline's GRP profiles are low in weight. This makes them easier to work with and means that great weight savings can be achieved on the finished structure.

Great strength

Fiberline Building Profiles give you the same great strength as steel, but at only a quarter of the density. It is also possible to make weight savings in comparison with aluminium, as the density is 30 % lower.


Our fibreglass profiles are resistant to aggressive chemicals, and liquids. This makes them ideal for wastewater treatment plants, swimming pools, cooling towers and construction, where there is a risk of corrosion.

Chemical resistance

Our fibreglass profiles are resistant to aggressive chemicals, liquids and alkalis. This makes them ideal for wastewater treatment plants, swimming pools, cooling towers and construction, where there is a risk of corrosion.

Electrical insulation

Fiberline's GRP profiles provide electrical insulation and minimise the complexity of earthing. This makes our profiles a future-proof choice where the costs of both installation and future inspections can be reduced considerably.

Easy to work with

GRP profiles are just as easy and fast to work with as timber. This means that solutions which incorporate our profiles can be installed easily on site or adjusted to fit existing components, such as piping systems, etc.

Thermally Insulating

Fiberline's fibreglass profiles have a significantly lower heat distribution gradient than steel and aluminium, enabling energy-efficient end products.

Minimal maintenance

Our GRP profiles have unrivalled durability and a long life, even in demanding conditions.


Fiberline's fibreglass profiles are produced using an energy-optimised process that takes the environment into consideration.

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