The technology is not limited to thermoset polymers. More recently, pultrusion has been successfully used with thermoplastic matrices such as polybutylene terephthalate (PBT), polyethylene terephthalate (PET) chopped strands by impregnating or wrapping the fiberglass powder in a sheet of thermoplastic matrix, which is then heated.
Compared to composites based on thermoset resins, the ecological cleanliness of the finished product and the almost unlimited recycling (processing) possibilities after resource depletion seem to be compelling arguments in favor of reinforced thermoplastics.
For these reasons, industrial production and the use of a given material have grown by 8-10% per year in highly industrialized countries in recent decades. New developments not only give a practical boost to the manufacture of both straight and curved profiles, but especially in the automotive sector, the demand for this technology is growing.
The pultrusion technique for making fiber glass composites from a polymer matrix appears to be energy and resource efficient.
Both economic and environmental factors favor the use of thermoplastic matrices, but due to the high viscosity of the melt, it is difficult to achieve high productivity and high quality fibrous filler impregnation with this type of matrices.