Carbon fiber is called "the king of new advanced materials" in building engineering.Mechanical properties and chemical properties are perfect.

Perfect Mechanical Properties of Carbon Fiber 

Carbon fiber is a new material with excellent mechanical properties, has two characteristics, strong resistance to tensile strength and soft processability of fiber. 

The tensile strength of carbon fiber is about 2 to 7GPa, and the tensile modulus is about 200 to 700GPa. The density is about 1.5 to 2 grams per cubic centimeter, which is mainly determined by the temperature of carbonization, except with the structure of the precursor. Generally, the density can reach 2 g per cubic meter after high temperature graphitization treatment at 3000 C. The weight is light, and its weight is lighter than the aluminum, and it is less than the steel 1/4, 20 times more than the strength of the iron. The thermal expansion coefficient of carbon fiber is different from other fibers, and it has the characteristic of anisotropy. The specific heat capacity of carbon fiber is generally 7.12. The thermal conductivity decreases as the temperature rises and the direction of the fiber parallel to the fiber is negative (0.72 to 0.90), while the direction perpendicular to the fiber is positive . The specific resistance of carbon fiber is related to the type of fiber. At 25 C, the high modulus is 775, and the high strength carbon fiber is 1500 per centimeter. This makes the carbon fiber with the highest specific strength and specific modulus in all high performance fibers. Compared with titanium, steel, aluminum and other metal materials, carbon fiber has the characteristics of high strength, high modulus, low density and low coefficient of linear expansion, which can be called "the king of new advanced materials".

Carbon fiber have it's general characteristics, its appearance has obvious anisotropy and soft, can be processed into a variety of fabrics, very small, along the fiber axis show a very high strength .Carbon fiber with the carbon fiber epoxy form carbon fiber reinforced polymer(CFRP),the strength and modulus of composite indicator in the existing structural materials is the highest. The tensile strength of carbon fiber composite materials are generally in more than 3500 MPa, is 7 to 9 times that of steel, the tensile modulus of 230 to 430G were also higher than that of steel; therefore the specific strength of CFRP material intensity and density can be achieved above 2000 MPa, the specific strength of A3 steel is only 59 MPa about the specific modulus than steel. Compared with the traditional glass fiber, the young's modulus (refers to the physical characterization at the elastic limit of material tensile or compressive) is more than 3 times ; Compared with Kevlar fiber, the young's modulus is about 2 times. 

Carbon fibers also have excellent fineness (one of the sizes of the representation of 9000 meters long fibers), generally only about 19 grams, and the tensile force is up to 300kg per micron. Almost no other materials have such a series of excellent properties, so they have strict requirements in terms of degree, stiffness, severe fatigue and so on. When it is not exposed to air and oxidants, carbon fiber can withstand high temperatures above 3000 degrees, and has outstanding heat resistance. Compared with other materials, when carbon fiber temperature is higher than 1500 degrees, carbon fiber will begin to decline, and the higher the temperature is, the stronger the fiber will be. The radial strength of carbon fiber is not as good as that of axial strength. Therefore, carbon fiber should avoid radial strength. In addition, carbon fibers also have good low temperature resistance, such as non embrittlement at liquid nitrogen temperature. 

Perfect Chemical Properties of Carbon Fiber 

The chemical properties of carbon fiber is like carbon, it can be oxidized by strong oxidizing agent and inert to general alkalinity. When the temperature in the air is higher than 400 C, there is obvious oxidation, CO and CO2 are generated. Carbon fiber has good corrosion resistance to general organic solvents, acids and alkalis. It is excellent in corrosion resistance. It doesn't exist rust. Researchers has been soaked in the PAN based carbon fiber in the alkali sodium hydroxide solution in 1981. It has been over 30 years, and it still maintains the fiber form.