Matrix 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. There are 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.
The choose of matrix can be decided according to the finished products application requirements and surroundings. “Suitability” is one of our designer’s last standards
Reinforcements Reinforcing materials can be various types of fiber roving, weaves and mats.
The orientation of reinforcements is important for the finished profile’s mechanical properties. And the combination of different reinforcements depends on the customer’s requirements in the profiles’ strength, load capacities in different directions.
Structural profiles are for example often subjected to loads that are transversal to the length of the profile (i.e. transversal to the direction of pultrusion), and these profiles must often be capable of resisting pull-out loads from bolts etc.
Under such situation, not only smooth unidirectional roving is therefore used, but also mats and weaves with different fiber orientations are used. Mats and weaves with fibre orientations of between 45° and 90° contribute primarily to improving bolt pull-out strength and mechanical properties in the transverse direction.
If a profile is to be located in a corrosive environment or often exposed to the sun, a special “surfacing veil” is used together with the above reinforcements.
The combination of roving, weave, mat and surface veil can be designed and decided according to the finished products application requirements and surroundings. “Suitability” is one of our designer’s last standards。