How to judge the performance of the wetting agent in the composite manufacturing process?

(1) Bunching. Bunching is one of the important indicators of fiber performance. The bundling of fiberglass is closely related to the LOI value of the sizing agent, the molecular weight of the film-forming agent, the adhesion and surface tension.

(2) Short-cutting property. Cutting property is particularly important for short-cut fibers. The requirements for film-forming agents for cutting property are the same as those for bundling property. In addition, the fiberglass is required to have a certain hardness after drying, which requires the film-forming agent to have a higher Tg. Since the hardness of glass is higher than that of steel blades, the fiberglass is broken by shearing force and impact force on the knife roller. Hard and brittle yarns are easy to break, but the impregnant film is easy to break after cutting, resulting in loose fibers and hairy fibers. Therefore, the impregnant film must also give the original fiber bundle appropriate toughness, so that the original fiber bundle is easy to break while maintaining the bundling and integrity of the short-cut original fiber.

(3) Dispersibility. The dispersibility of the chopped fibers in the resin requires the sizing agent to have good bundling, integrity and fluidity of the chopped fibers. There should be less fuzz, fuzz and fiber opening, and the corresponding film-forming agent should have low surface tension, smooth surface and low electrostatic effect.

(4) Penetration. The ability of the resin to completely penetrate the fiberglass requires that the film-forming agent in the sizing agent has high solubility and low molecular weight. This property is mostly used for the sizing requirements of winding and pultrusion soft yarns.

(5) Penetration. The ability of the resin to penetrate the fiberglass laterally. The fiber must be well bundled, the film-forming agent must have low solubility, and it must not be easy to open the fiber in the liquid resin.