二、Glass fiber mat application requirements

  Hand lay-up: Hand lay-up is the main method of FRP production in my country. Glass fiber chopped strand mat, continuous mat and Fiberglass Needle Mat can all be used for hand lay-up. The use of stitch-bonded felt can reduce the number of layers and improve the efficiency of hand lay-up operations. However, because the stitchbonded felt contains more chemical fiber stitchbonding threads, the bubbles are not easy to drive away, and the fiberglass products have many needle-shaped bubbles, and the surface feels rough and not smooth. In addition, Needle Mat's mold coverage is shorter than that of cut felt and continuous felt. When making products with complex shapes, it is easy to form voids at the bend. The hand lay-up process requires the mat to have the characteristics of fast resin infiltration rate, easy elimination of air bubbles and good mold coverage.

  Pultrusion: The pultrusion process is one of the main uses of Fiberglass combo mat and stitchbonded mats. Generally, it is used in combination with untwisted roving. Using combo mat and stitched felt as pultruded products can significantly improve the hoop and transverse strength of the products and prevent the products from cracking. The pultrusion process requires the mat to have uniform fiber distribution, high tensile strength, fast resin infiltration rate, good flexibility and mold filling, and the mat should have a certain continuous length.

  RTM: Resin transfer molding (RTM) is a closed-mold molding process. It is composed of two half-moulds, a female mold and a male mold, a pressurizing pump and an injection gun, without a press. The RTM process typically uses continuous mats and stitched mats instead of e-glass chopped strand mat. The felt sheet is required to have the characteristics that the felt sheet should be easily saturated with resin, good air permeability, good resin scour resistance and good overmoldability.

  Winding process: Generally, chopped strand mat and continuous mat are used for winding and forming the resin-rich layer mainly used for products, including inner lining layer and outer surface layer. The requirements for the glass fiber mat in the winding process are basically similar to those in the hand lay-up method.

  Centrifugal casting molding: chopped strand mat is usually used as raw material. The chopped strand mat is pre-laid in the mold, and then the resin is added into the rotating open mold cavity, and the air bubbles are discharged by centrifugation to make the product dense. The felt sheet is required to have the characteristics of easy penetration and good air permeability.