Pultrusion
Pultrusion is a continuous manufacturing process used to create Glass-fiber Reinforced Polymer (GRP) composites with a constant cross-section. The process begins with fibers such as glass, carbon, or aramid, which are passed through a resin bath containing a thermosetting resin (such as polyester, vinyl ester, or epoxy). These resins are designed to provide mechanical strength and chemical resistance to the final product. The impregnated fibers are then pulled through a heated die, where the material is shaped and cured into a solid form.
In terms of technical specifications, the fiber volume fraction typically ranges between 50% to 70%, depending on the desired strength and stiffness. The die temperature is generally between 120°C and 180°C, which facilitates curing and hardening of the resin. The pulling speed of the fibers, a critical parameter, is usually around 0.5 to 2 meters per minute, depending on the complexity of the profile and the type of resin used.
Pultrusion delivers consistent product quality, with the high fiber volume fraction ensuring strong mechanical properties such as tensile strength (ranging between 600 to 2400 MPa, depending on the fiber type) and flexural strength. The materials produced are resistant to corrosion, making them useful in harsh chemical environments. This method also allows for customization of material properties by adjusting the type of fibers and resins used, making it suitable for producing products with tailored specifications such as electrical conductivity or thermal insulation.
Pultruded products are widely used in industries requiring lightweight but structurally strong materials. The construction industry uses these materials for structural profiles like beams, gratings, and handrails, with typical profile dimensions ranging from small cross-sections (a few millimeters) to large ones (several hundred millimeters). The chemical and oil industries employ pultruded gratings and supports due to their chemical resistance and non-conductive properties. The electrical industry uses pultruded profiles for high-voltage insulators due to their dielectric strength, typically around 10 kV/mm.
