T300 VS T700 carbon fiber

Carbon fiber (CF for short) is a new type of fiber material with high strength and high modulus fiber with a carbon content of more than 95%.

The T number of fibers refers to the grade of carbon materials. In the industry, it refers to a certain type of carbon materials produced by Toray Company in Japan. Outside the industry, it generally refers to ultra-high-precision carbon materials. How many T refers to the tonnage of tensile force that this type of carbon fiber can withstand with a cross-sectional area of 1 square centimeter. Therefore, in general, the higher the T number, the higher the carbon fiber grade and the better the quality.

Carbon fiber T300 was first invented by Japan’s Toray Company in the 1970s, and then three series of carbon fibers were developed, namely high-strength T-series, high-modulus M-series, and MJ-series carbon fibers with both high-strength and high-modulus. In recent years, T700 has replaced it. T300 has become a new generation of general-purpose carbon fiber. In fact, T800 and T1000 have been mass-produced in Japan and some countries in Europe and America.


Both T300 and T700 have the same tensile modulus of 230Gpa and diameter of 7μm, but in terms of tensile strength, the difference between the two is very large. T300 is 3.53Gpa, while T700 has reached 4.90Gpa, which is much higher than the former. 38.8%, and the elongation at break of T700 increased by 40%, and the bulk density increased by 2.27%.

Elemental composition

It has been confirmed by scientific experiments that the chemical composition of T300 and T700 is mainly carbon, the mass fraction of the former is 92.5%, the latter is 95.58%; followed by nitrogen, the former is 6.96%, the latter is 4.24%, compared with T700 carbon The content is significantly higher than that of T300, and the carbonization temperature is higher than that of T300, which makes its carbon content brighter and nitrogen content lower.


Due to the different spinning processes, the surfaces of T300 and T700 show significantly different characteristics. The surface of T300 is bark-like and has obvious grooves of different depths, which are the characteristics of wet spinning process. The T700, on the other hand, exhibits a smooth surface that is characteristic of the dry jet wet spinning process.

The shape of the cross section

Both T300 and T700 carbon fibers have granular features, the fibril bundle structure is clearly visible, there are axial micropores between each other, and the fiber density is relatively uniform. Moreover, it can also be judged from the surface morphology of the SEM image that the process used for T300 is wet spinning of raw yarn, while the process of T700 is to use dry-jet wet spinning of raw yarn.

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