In the standard pultrusion process the reinforcement materials like fibers or woven or braided strands are impregnated with resin, possibly followed by a separate preforming system, and pulled through a heated stationary die where the resin undergoes polymerization. The impregnation is either done by pulling the reinforcement through a bath or by injecting the resin into an injection chamber which typically is connected to the die. Many resin types may be used in pultrusion including polyester, polyurethane, vinylester and epoxy. Resin provides the resistance to the environment, (i.e., the corrosion resistance, the UV resistance, the impact resistance, etc.) and the glass provides strength, in addition to safety from fire.
Advantages of Pultrusion
- Improved structural properties of laminates
- Volatile emissions are limited by enclosing the resin impregnation area
- High glass content is achievable
Disadvantages of Pultrusion
- It is difficult to pultrude a profile with complex cross section
- High initial investments.
- Only the uniform cross section profiles are feasible.