Fibre-reinforced composites (FRC) are multi-phase or mixed materials consisting of a matrix and reinforcing fibres. Thanks to the mutual interactions between both components, their joined properties are significantly better than the ones of the individual components. FRC play an important role in our daily lives, with applications ranging from sports equipment, household goods, buildings, bridges, automobiles, boats to aerospace. The fibre materials mainly consist of glass, carbon, aramid or basalt. They are applied in the form of woven fabrics, scrims, braids, knitted fabrics, nonwovens or rovings. Epoxy, polyester, polyurethane or vinyl ester resins and thermoplastic polymers are generally used as matrixes.
In the case of thermoset composites, the matrix curing step consumes an extremely high amount of both energy and time, resulting in long processing times, slow production rates and high production costs. Therefore, composite manufactures are looking for alternative methods to speed up the process and to lower the costs.
During the CORNET-Project LEDcure (IWT 120626) the feasibility has been demonstrated to cure composites made from fibreglass in a fast and energy efficient way with UV-LED curing systems thanks to the UV-transparency of fibreglass. However, a large percentage of composites are made from other fibres, including carbon, aramid and basalt. Research into new ways to cure these materials too in an energy efficient manner is greatly needed.
In this new project, efficient methods will be developed to cure composites containing non UV-transparent fibres. As many applications also require fire retardant properties, this property will be included.
Different research strategies will be explored to reach this goal:
DEVELOPING HYBRID FABRICS: UV-transparent fibres will be incorporated in basalt or carbon fabrics (braids and weaves) and even in recycled carbon nonwovens. These fabrics and nonwovens will then be impregnated with UV-curable resins. The UV-transparent fibres will ensure that UV-light penetrates deeper into the material resulting in a better through curing.
ELECTRON BEAM (EB) CURING: EB curing requires similar chemistry as UV-curing. Howver, because electron beams are more energetic, they can cure deeper. Moreover, the fibres do not have to be UV-transparent.
INFRARED CURING: Infrared light is a more efficient technique to heat up materials compared to convection heating and it will be investigated if this technique can be used as drying method to obtain prepregs or even for full curing.
DUAL CURING: dual cure resins can be cured by light or by heat. The resins that are exposed to the light will cure instantly. As a result the composite is already dry and can be easily transported. Full curing is then achieved by time or heat.
FIRE RETARDANCY: Fire retardancy will be achieved by adding FR additives or by using FR resins.
The project targets the suppliers of raw materials (resins and FR additives), the textile industry (manufacturing of textile reinforcements), the textile coating and finishing industry (formulations and fibre impregnation) and the composite industry (laminating and curing).