Continuous carbon fiber thermosetting composite 3D printing technology has been developed

Continuous carbon fiber thermosetting composite 

3D printing technology has been developed

Carbon fiber reinforced polymer (CFRP) is a composite material with excellent performance, but it can only be made of continuous carbon fiber to have excellent performance. Once these carbon fibers are chopped and mixed with the thermoplastic matrix, most of the advantages of the carbon fiber reinforced plastic structure will be lost. In the case of chopped fibers, the carbon fiber no longer bears the load, and is actually only used as a filler.

The same is true for 3D printing technology. At present, many 3D printing technologies related to CFRP are based on short carbon fiber reinforced thermoplastic composite materials. Therefore, any new method that can use continuous carbon fiber for 3D printing will attract people's interest.

Recently, a research team from the University of Delaware has invented a new method that demonstrates a method of using continuous carbon fiber and a thermosetting polymer matrix for its 3D printed composite materials, instead of the usual The thermoplastic polymer serves as the matrix. What is the difference between thermoset and thermoplastic? Why is it significant?

1.Thermosetting resin and thermoplastic resin

Thermoplastics (such as ABS resin) melt when heated at high temperatures, and harden when it cools. This heat treatment process can be repeated, and the polymer can be remelted many times without any physical changes to the material.

But for thermosetting plastics, after the resin matrix is heated and solidified, it will basically solidify into a solid permanently after cooling. This process is irreversible.

Some composite materials, such as aerospace, may be exposed to high temperature ranges during application, so the resin matrix needs to not melt when heated, so a carbon fiber/thermoset composite system is required. Thermoset plastics also have good fatigue resistance, which is also attractive in aerospace applications and sporting goods. Currently, 95% of carbon fiber composite components for aviation use thermoset prepreg.

2.Continuous carbon fiber thermosetting composite 3D printing

The research team from the Center for Composite Materials (CCM) at the University of Delaware recognized this need for thermoset CFRP printing, so they developed Localized In-plane Thermal Assisted (LITA) 3D printing system. It uses a unique print head and automatic robotic arm.

Using this system, the research team was able to guide the carbon fiber into the desired shape and control the temperature of the fiber through a Joule heater to guide the flow of liquid polymer. This allows the thermosetting resin to flow and wick into the channels between the fibers before curing, thereby forming a strong, thermally stable three-dimensional structure.

From a technical point of view, the basic concept of LITA technology is based on the continuous capillary effect or wicking effect, which is achieved by the thermal gradient moving along the surface of the carbon fiber, which promotes the flow of liquid polymer into the tubular space between adjacent carbon fibers Then, the polymer resin is cured from the heated fiber surface to the surrounding space.