Thermoset Resins

Types of Thermoset Resins

Bakelite is one of the more recognizable brand names in thermoset manufacturing, being the first synthetic plastic produced and a common choice for consumer goods well into the mid-20th-century. However, there is now a broad range of thermoset resins available to manufacturers with characteristics that suit a diverse set of applications. Some of the most commonly used thermoset resins include:

• Epoxy resins are among the most popular thermosets due to their strength, toughness, and resistance to damage from chemical and environmental exposure.
• Vinyl ester resins are more cost-effective than epoxy resins while still providing strength, durability, and corrosion resistance.
• Polyester resins are widely used across manufacturing, especially for the production of fiber-reinforced polymer (FRP) composites.

Benefits of Thermoset Resins

Compared to thermoplastic resins, thermoset resins offer a number of benefits. For example:

• They are typically in a liquid state prior to curing, making them easy to work with during molding and other manufacturing operations and apply to fabrics and other fiber-based materials when creating prepregs.
• They are strong, durable, and thermally resistant after curing, making them suitable for use in demanding applications involving heavy loads and high temperatures, especially when combined with fibers, fillers, and other additives to produce composite materials.

Some of the other key benefits of thermoset resins include:

• Chemical and solvent resistance
• Ability to form strong adhesive bonds
• Suitability for a variety of finishing operations (e.g., polishing and painting)

Uses of Thermoset Resins

Thermoset resins find use in a wide range of industrial and consumer parts and products. For example:

• Epoxy resins are used for adhesives, coatings, and fiber-reinforced plastics (FRPs).
• Polyester resins are used for sheet molded and bulk molded components.
• Polyimide resins are used for printed circuit boards (PCBs).
• Polyurethane resins are used for adhesives, insulating foams, and mattresses.

They can be used in a variety of manufacturing processes in their liquid state. However, integrating them into prepregs helps simplify operations.

The Role of Thermoset Resins in Prepreg Production

Prepregs are fabrics and other fiber-based materials pre-impregnated with resin to reinforce the material structure. Typical parts and products produced with prepregs include:

• Aircraft components
• Pressure vessels
• Orthotics and prosthetics
• Circuit boards
• Insulating rods
• Pipes
• Boats
• Recreational equipment (e.g., bicycle frames, skateboards, skis, and snowboards)
• Rocket housings

Both the type of fiber and resin employed for a prepreg vary depending on the part and production specifications. Common reinforcing fibers include aramid, basalt, carbon, and fiberglass. The resin component can be thermoplastic or thermosetting. Compared to thermoplastic resins, thermosetting resins offer many advantages in prepreg manufacturing operations. The primary advantage is that they are processable at room temperature, which makes it easy to impregnate the chosen fibers before curing. In contrast, thermoplastic resins are typically solid at room temperature, making it much harder to apply them to the fibers. Thermoset resins do not just offer easier application requirements. They also add or enhance the properties of the final composite material. For example, they improve its overall strength, chemical resistance, and thermal stability. In return, the fiber matrix provides structure to the thermoset resin in its partially cured state. Thermoset prepregs are shipped partially cured—i.e., in the B Stage—to make it easier for manufacturers to position them within the mold or machine tool during production operations. They generally ship with backing film on both sides to protect them during transit and pre-production preparation. The film is removed after the material is cut to the proper shape and size and before it is placed into the manufacturing equipment. The prepreg is then subjected to heat and pressure—depending on the specific resin employed—to harden it in the desired form.

Thermoset Epoxy Prepregs From APCM

Thermoset resins—especially thermoset epoxy resins—are an essential component of many prepreg production operations. In turn, the materials produced are used in the manufacture of numerous industrial and consumer parts and products. If you’re looking for a reliable supplier of high-quality thermoset prepregs, turn to the experts at APCM. At APCM, we’ve provided thermoset epoxy prepregs for composite part designers, manufacturers, and hobbyists for almost 30 years. They are available with a variety of composite fiber material options, including Dyneema®, Kevlar®, and Spectra®, and in roll, sheet, and pre-cut segment forms. While there are a few exceptions, all of our prepregs have cumulative out-time expiration dates of 30 days. However, they can be refrigerated for up to 6 months or frozen for longer storage requirements. Our composite materials are strong, lightweight, and easy to use. However, we are continuously looking for ways to improve their weight, strength, and ease of use even further. To learn more about prepreg products and services, contact us today.