Filler is a very important component in the pultrusion process. It can improve the processing performance of the resin system and the properties of the cured products when it is used properly. If it is used improperly, it will seriously affect the processing performance and product performance.
Generally, any powder mineral can be used as filler. The influence of fillers on the liquid resin system is to increase the viscosity, produce thixotropic, accelerate or block curing, reduce heat. In the process of its influence, the most important is the influence of viscosity properties. And the influence of the viscosity is the main oil absorption rate. Oil absorption rate increased the viscosity, or in other words, in the case of maintaining the same viscosity, oil absorption rate is lower, then the amount of the filler can be greater.
The price of the filler is also an important reference for choosing which kind of material to use. The lowest cost is heavy calcium carbonate and talc powder, surface activation of a slight increase in the cost of heavy calcium carbonate, the highest is aluminum hydroxide. Aluminum hydroxide is usually used as flame retardant filler and filler used as ordinary.
The influence of various fillers on the mechanical and physical properties of the cured products is roughly equivalent. Slightly different effects on the flame retardant properties and electrical properties. I n addition, the dynamic mechanical properties of the products are more complex, and the particle size, particle size distribution, particle shape, hardness and filling amount of the products are related.
In summary, the choice of the filler should be regarded as the final performance requirements of the FRP product. In ordinary circumstances, the performance of the best and the lowest cost of the filler is a heavy calcium carbonate and surface activated heavy calcium carbonate. In addition, unless there are special requirements, generally we don’t recommend to use composite (at the same time using two or more than two kinds of fillers) filling system.