What Influence Do Raw Materials Have On The RTM Process?

 

The properties of raw materials, resin viscosity, surface tension, fiber surface treatment, fiber arrangement, fabric form and resin wettability are all important factors affecting the RTM process and the quality of parts.

 

The purpose of emphasizing these factors is mainly to enable the resin to fully infiltrate the fibers as quickly as possible, so that the resin/fiber system has strong penetration and wetting ability, and the parts have good quality and short molding cycle.

 

In a heterogeneous porous fiber medium, the fibers in the fiber bundle are tightly packed, and the fluidity of the resin in it lags behind the overall fluidity. Although surrounded by resin, there is a lack of sufficient pressure difference due to the gas encapsulated in it to allow the resin to penetrate into the fiber bundle quickly.

 

When the resin has a low viscosity, the fiber bundle is easy to be infiltrated, the fiber surface treatment is good, the wettability with the resin is good, and the surface tension of the resin is large, forming a large capillary pressure, the resin is easy to penetrate into the fiber bundle, better discharge the bubbles in it, improve the quality of the parts, and shorten the process cycle.

 

Therefore, many researchers believe that the resin should have a low viscosity. Low viscosity means that the resin is easy to flow in the fiber medium, especially when the fiber content is high, the resin can still penetrate the entire medium and infiltrate the fiber without too much pressure, thereby reducing mold deformation and fiber slippage.

 

Sometimes the mold is heated to reduce the viscosity of the resin, which speeds up the viscosity increase of the composite material and reduces the active period.