Advantages and disadvantages of fiberglass-1

Fiberglass is a composite material that has developed rapidly in the past fifty years. 70% of the output of glass fiber is used to make fiberglass. Fiberglass has high hardness and is much lighter than steel. It can be used as fuel tank and pipeline on jet aircraft to reduce the weight of the aircraft. Astronauts on the moon, the miniature oxygen cylinders on their backs are also made of glass fiber reinforced plastic material. Fiberglass is easy to process, not rusty and not rotten, and no paint is needed. Our country has widely adopted fiberglass to manufacture various small motorboats, lifeboats, yachts, and automobile manufacturing industries, saving a lot of steel. Since fiberglass is a composite material, its performance adaptability is very wide, so its market development prospects are very broad. According to relevant statistics, the types of FRP products developed by countries around the world have reached about 40,000. Although all countries have their own development directions based on their own economic development, they have basically involved various industrial sectors. After more than 40 years of development, my country's FRP industry has also achieved successful applications in various fields of the national economy and has played an important role in economic construction.

The main advantages of FRP are as follows:

1) Lightweight and high strength. The relative density is between 1.5 and 2.0, which is only 1/4 to 1/5 of that of carbon steel, but the tensile strength is close to or even higher than that of carbon steel, and the specific strength is comparable to that of high-grade alloy steel. Therefore, it has excellent results in aviation, rockets, space vehicles, high-pressure vessels, and other products that need to reduce their own weight. The tensile, flexural and compressive strengths of some epoxy FRP can reach more than 400Mpa.

2) Corrosion resistance. FRP is a good corrosion-resistant material, and has good resistance to atmosphere, water and general concentrations of acids, alkalis, salts, and a variety of oils and solvents. It has been applied to all aspects of chemical corrosion protection and is replacing carbon steel, stainless steel, wood, non-ferrous metals, etc.

3) Good electrical performance. It is an excellent insulating material, used to make insulators. It can still protect good dielectric properties under high frequency. It has good microwave permeability and has been widely used in randomness.

4) Good thermal performance. FRP has low thermal conductivity, 1.25~1.67kJ / (m•h•K) at room temperature, which is only 1/100~1/1000 of that of metal. It is an excellent thermal insulation material. It is an ideal thermal protection and ablation resistant material in the instantaneous ultra-high temperature situation, and can protect the spacecraft from the erosion of high-speed airflow above 2000 ℃.

5) Good design ability. Various structural products can be flexibly designed according to needs to meet the requirements of use, which can make the product have a good integrity; materials can be fully selected to meet the performance of the product, such as: corrosion resistance and instantaneous high temperature resistance can be designed, The product has particularly high strength and good dielectric properties in a certain direction, and so on.

6) Excellent manufacturability. The molding process can be flexibly selected according to the shape, technical requirements, use and quantity of the product; the process is simple, it can be molded at one time, and the economic effect is outstanding, especially for products with complex shapes and small quantities that are not easy to form, and its process superiority is more prominent.

The main disadvantages of FRP are as follows:

1) Low modulus of elasticity. The elastic modulus of FRP is two times larger than that of wood, but 10 times smaller than that of steel (E=2.1×105). Therefore, the product structure often feels insufficient rigidity and is easy to deform. It can be made into a thin shell structure, a sandwich structure, or made up of high modulus fibers or reinforcement ribs.

2) Poor long-term temperature resistance. Generally, FRP cannot be used for a long time at high temperature. The strength of general-purpose polyester FRP decreases significantly above 50°C, and generally only used below 100°C; general-purpose epoxy FRP has a significant decrease in strength above 60°C. But it is possible to choose high temperature resistant resin, so that the long-term working temperature is 200~300℃.

3) Aging phenomenon. Aging phenomenon is a common defect of plastics, and FRP is no exception. Under the action of ultraviolet rays, wind, sand, rain, snow, chemical media, and mechanical stress, it is easy to cause performance degradation.

4) Low shear strength. The interlinear shear strength is borne by the resin, so it is very low. The bonding force between layers can be improved by selecting processes and using coupling agents. The most important thing is to avoid shearing between layers as much as possible during product design.