Analysis And Optimization Of Water-bath Drafting Processes On PAN Precursor Used In Carbon Fiber

Carbon fiber is a kind of fiber material with more than 90% of carbon content, and because of its high strength and high modulus, increasingly widely being used. Production process of polyacrylonitrile-based carbon fiber is currently the most simple and the performance of carbon fiber also is best. The quality of the carbon fiber to a large extent depends on the quality of PAN. The structure of primary fiber loose, the intensity is low, so it cannot be directly applied. Through the drafting process the fiber structure could be improved, as well as its performance could be enhanced, making it a high quality yarn. Water bath stretching is an important part of the drafting process, therefore, the studies on the process of drafting is of very important significance on improving the quality of PAN.This paper consists of the following research:(1) As be explored in the drafting process of the primary fiber, the degree of influence of different draw conditions (stretch ratio, temperature, etc) on the orientation, found that effect of bath stretch ratio on the orientation of higher degree is very strong.(2) In the drafting process of PAN, to ensure other conditions constant, by observing structures and properties of fiber under different stretch ratio, the effect of drafting ratio on strand orientation could be explored, found that in the drafting process, if the total stretch ratio keep in the 6-8 and in water-bath draft the stretch ratio is below 1.8 times, the quality of the fiber is the best.(3) By changing the conditions of drawing, watching change of stress-strain curves in the drafting process could further help to understand mechanical properties and structural changes of the fiber in the process of the water-bath drafting.(4) By studying on the relation between deformation behavior and mechanical, mathematical models based single fiber drawing process of stretch rate and tension could be derived. Simulation by MATLAB could verify the accuracy of the model.(5) Through adjusting MATLAB model(add some auxiliary modules), the mode of fracture stress with the maximum stretch ratio can be determined. Under the optimal conditions of drawing this model can get the fiber’s best stretch ratio without having to break.Through the above experimental analysis and simulation, the produce of industrial carbon fiber precursor production carry out exploratory research, with providing a reference for future production.