Analysis of the Reasons for the Gap in Carbon Fiber Technology Between China and Other Countries

The preparation process of carbon fiber is lengthy, mainly including dozens of technological processes such as raw material synthesis, fiber forming, preoxidation, and carbonization. It involves the complex and profound scientific connotations of polymer chemistry, polymer physics, and materials science, and it is indeed a technically challenging project in materials science. Only with the support of sufficient basic scientific theories, the guarantee of basic industrial technologies, and the three elements of fine operation and strict management can success be achieved. However, the current situation of China's carbon fiber industry shows that these three elements are all lacking, and the weakest is the research on basic scientific theories.

Over the past three decades of scientific research, Chinese researchers, after numerous successes and failures, have finally reached a consensus on the factors hindering carbon fiber development. They agree that the long-standing backwardness of precursor fiber production has been the primary bottleneck in improving carbon fiber quality. The critical role of precursor fiber in carbon fiber production underscores the principle that inherent deficiencies are difficult to overcome.

Due to the influx of second- and third-tier precursor fibers from abroad in recent years, it has become possible to make comparisons. Currently, it has been found that except for diameter, strength, and crystal orientation, the initial modulus, elongation at break, molecular weight and its distribution, thermal properties, and elemental analysis are basically similar. There are significant differences in fiber morphology and structure: in addition to the diameter being not as fine as foreign precursor fibers and having a large deviation, SEM photos also clearly show that domestic precursor fibers have more and larger defects and pores. The strength data is slightly lower, the uniformity is larger, and the crystal orientation is smaller. Whether these gaps are the key to the difference in quality between the two types of precursor fibers is still uncertain, but the lack of key indicators for measuring precursor fibers is indeed one of the serious problems in the current preparation of domestic precursor fibers.

Defects are the main factors leading to the decrease in material strength, and they are even more fatal to typical brittle materials such as carbon fiber. However, in-depth research on the causes of defect formation, especially on how defects are generated and how they can be avoided in the precursor fiber and during the conversion of precursor fiber to carbon fiber, is very limited. Therefore, the development of carbon fiber in China has stagnated for a period of time, and the gap with foreign countries has become increasingly wider.