Resin selection for composite materials

The main components of composite materials are fibers and resins. Fibers are usually selected as either glass fiber or carbon fiber, which can enhance the required strength and stiffness of the product. But if used alone, it still cannot meet the final performance of the product. If fibers are impregnated with resin and then cured, they can meet the strength, stiffness, and lightweight requirements of various application designs, while adding many benefits to the final product.

Supplement to existing features

All composite materials have common advantages: higher strength, stiffness, lighter weight, and better environmental resistance. Each of these features can become more prominent by using supplementary resins. To choose the most suitable resin, the first step is to determine what the main characteristics of the composite material should be.

The most cost-effective method to produce lightweight composite materials is to use unsaturated polyester resin. This speciality resin has relatively good mechanical, electrical, and chemical properties, making it suitable for a range of conventional applications such as transportation, structure, and building profiles.

However, if higher stiffness or strength is required, then cycloaliphatic epoxy resin is undoubtedly the best. The strong bonding between epoxy resin and fibers means that higher shear loads can be transferred between fibers, giving composite materials higher strength values. By combining the higher fiber content allowed by epoxy resin, composite materials with excellent strength and high stiffness can be made. If necessary, further modifications can be made to adapt to high-temperature applications.

In addition, if composite epoxy material needs to be resistant to harsh environments in addition to hardness, vinyl ester resin may be a better choice. The molecular structure of vinyl esters has chemical resistance, therefore, if composite materials are to be used in marine environments or industrial applications with acid or alkali, the use of vinyl esters will improve the performance of the composite materials.

When producing composite profiles that require assembly with screws, the composite material must be sturdy to prevent cracks and fractures. This can be achieved through structural design, but selecting the appropriate resin can simplify the structure, reduce costs, and make composite materials suitable for a wider range of applications. For example, compared to unsaturated polyester, polyurethane has extremely high toughness, making it an ideal choice for such applications.

Add new features

Choosing a resin that can supplement the most valuable features of composite materials will improve their performance and lifespan. However, the benefits of spending time choosing resins go far beyond improving existing properties.

Resin can also add new characteristics to composite material products. Resin additives can be added to resins to achieve a range of benefits, ranging from simply improving surface smoothness or increasing color, to more complex enhancement functions such as UV resistance, antibacterial, or antiviral properties.

For example, due to the natural decomposition of resin when exposed to sunlight, adding UV absorbers to resist UV radiation can improve the performance of composite materials in environments with strong light exposure, which often leads to material embrittlement and disintegration.

Similarly, antibacterial additives can be mixed into the resin to prevent bacterial or fungal contamination. This is useful for any composite material product that involves manual operation, such as machinery, public transportation, and medical equipment.

Other external influences

It is worth noting that in some cases, the addition of resin additives can alter the properties of composite materials. For example, in some extreme cases, a large amount of flame retardant additives are required to effectively exert their effects. At this point, it is necessary to reduce the number of fibers in the composite material, correspondingly reducing its strength and stiffness.

Resin selection is an important part of the overall design of composite materials and should not be ignored. Establishing the most necessary characteristics of composite materials, combining them with suitable resins to enhance this characteristic, while balancing the balance between fibers and resins, is essential to create the best solution.