Advantages of FRP
1. FRP is lightweight and high-strength
The relative density is between 1.5~2.0, only 1/4~1/5 of carbon steel, but the tensile strength is close to or even exceeds that of carbon steel, and the specific strength can be compared with advanced alloy steel. Therefore, it has excellent results in aviation, rockets, spacecraft, high-pressure vessels and other products that need to reduce their own weight. The tensile, bending and compressive strength of some epoxy FRP can reach more than 400Mpa.
2. Corrosion resistance
FRP is a good corrosion-resistant material, and it has good resistance to the atmosphere, water, and general concentrations of acids, alkalis, salts, and various oils and solvents. It has been applied to all aspects of chemical anticorrosion, and is replacing carbon steel, stainless steel, wood, non-ferrous metals, etc.
3. Good electrical performance
It is an excellent insulating material and is used to make insulators. It can still protect good dielectric properties at high frequencies. It has good microwave permeability and has been widely used in radar radomes.
4. Good thermal performance
FRP has low thermal conductivity, 1.25~1.67kJ/(m·h·K) at room temperature, only 1/100~1/1000 of that of metal, and is an excellent thermal insulation material. In the case of instantaneous ultra-high temperature, it is an ideal thermal protection and ablation-resistant material, which can protect the spacecraft from being scoured by high-speed airflow above 2000 °C.
5. Good designability
(1) According to the needs, various structural products can be flexibly designed to meet the requirements of use, which can make the product have a good integrity.
(2) Materials can be fully selected to meet the performance of the product, such as: corrosion-resistant, instantaneous high-temperature resistant, particularly high-strength in a certain direction of the product, good dielectric properties, etc. can be designed.
6. Excellent craftsmanship
(1) The molding process can be flexibly selected according to the shape, technical requirements, usage and quantity of the product.
(2) The process is simple, it can be formed at one time, and the economic effect is outstanding, especially for products with complex shapes and small quantities that are not easy to form, its process superiority is more prominent.
Disadvantages of FRP
1. The elastic modulus of FRP is low
The elastic modulus of FRP is twice as large as that of wood, but 10 times smaller than that of steel (E=2.1×105), so it often feels insufficient rigidity in the product structure and is easy to deform.
It can be made into a thin shell structure, a sandwich structure, or it can be made up by high modulus fibers or ribs.
2. Poor long-term temperature resistance
Generally, FRP cannot be used at high temperature for a long time. The strength of general-purpose polyester FRP drops significantly above 50°C, and is generally only used below 100°C; the strength of general-purpose epoxy FRP drops significantly above 60°C. However, high temperature resistant resin can be selected, so that the long-term working temperature is possible at 200~300°C.
3. Aging phenomenon
Aging phenomenon is a common defect of plastics, and FRP is no exception. It is easy to cause performance degradation under the action of ultraviolet rays, wind, sand, rain and snow, chemical media, and mechanical stress.
4. Low shear strength
The interlaminar shear strength is borne by the resin, so it is very low. The interlayer adhesion can be improved by selecting a process, using a coupling agent, etc. The most important thing is to avoid shearing between layers as much as possible during product design.