What is the difference between carbon fiber T300 and T700?

What is the difference between carbon fiber T300 and T700?

Carbon fiber T300 was first invented by Japanese company Toray in the 1970s, and then three major 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 T300 as a new generation of general-purpose carbon fiber. In fact, T800 and T1000 have been mass-produced in Japan and some European and American countries.

Due to the monopoly position of Dongli Company in the carbon fiber industry, its high-strength series carbon fibers have become the industry benchmark. When it comes to technical parameters, they must be referred to as T300 level, T700 level, T1000 level, and so on. Here we will talk about the difference between carbon fiber T300 and carbon fiber T700.

From a performance perspective

T300 and T700 both have the same tensile modulus of 230Gpa and a diameter of 7 μ m. However, there is a significant difference in tensile strength between the two, with T300 reaching 3.53GPa and T700 reaching 4.90GPa, which is 38.8% higher than the former. Additionally, the fracture elongation of T700 has increased by 40% and the bulk density has increased by 2.27%.

From the perspective of element composition

After scientific experiments, it has been confirmed that the chemical composition of T300 and T700 is mainly carbon, with a mass fraction of 92.5% for the former and 95.58% for the latter; Next is nitrogen, with the former accounting for 6.96% and the latter accounting for 4.24%. In contrast, the carbon content of T700 is significantly higher than that of T300, and the carbonization temperature is higher than that of T300, resulting in higher carbon and lower nitrogen content.

From the appearance

Due to different spinning processes, the surfaces of T300 and T700 exhibit significantly different characteristics. Among them, the surface of T300 is bark like and has distinct grooves of varying depths, which is a characteristic of wet spinning processes. The T700 exhibits a smooth surface, which is a characteristic of the dry spray wet spinning process.

From the morphology of the cross-section

Both T300 and T700 carbon fibers exhibit granular characteristics inside, with clear and visible original fiber bundle structures and axial micropores between them. The density of the fibers is relatively uniform. Moreover, the surface morphology of SEM images can also determine that T300 uses wet spinning precursor, while T700 uses dry spray wet spinning precursor. Wet spinning and dry jet wet spinning, although only a short air layer, do have a significant impact on the performance of carbon fibers. So in the entire production process, there are many small differences that can affect the final performance of carbon fibers.

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