Abstract

Carbon fiber is trading between 14 and 20 euros per kilo. This price is still too high to find composite applications based on carbon fiber in mass market applications such as automotive and sports and leisure industry. This is why we work in a large French consortium called FORCE, with the target of creating a French economic carbon fiber sector.

We are now in the second phase of the project: carbon fiber production at laboratory and pilot scale. New precursors, as alternative to PAN, are evaluated: bio-sourced raw materials such as lignin and cellulose and polyethylene. The targeted mechanical properties are Young's Modulus of 250GPa and tensile strength of 2500MPa.

The 2 first years of this phase were marked by noticeable progress in the different workpackages of the project.

The work involved has made it possible to structure the overall planning of the FORCE program with the vision of setting up the industrial line and the marketing of low-cost fiber.

FORCE project phase II is now at the pilot line scale development.

A carbonization pilot line is now running in Lacq (SW of France). It has been co-funded by the Conseil Régional de Nouvelle-Aquitaine and IRT Jules Verne. It is a polyvalent continuous line able to produce enough carbon fibers for the realization of composite demonstrators, to carbonize different kinds of precursors, and to demonstrate the feasibility of further industrialization. This line is able to produce more than 1 t/year of carbon fibers.

Due to very good results with cellulose, work continues on this precursor only. This work is focused on the development of innovative formulations and processes with a number of actions such as: reducing the diameter of the filaments; investigating new technologies for heating; optimizing the carbonization step through the design of experiments, simulations, and hands-on experience.

The latest results obtained with a carbonized fiber at the laboratory scale are very close to the mechanical objective. These results have already been confirmed on the pilot line in Lacq during the 2nd part of 2019.

In our presentation we will detail:

• The work on the raw materials to obtain the best compromise between cost and performance with focus on raw materials from circular economy such as cellulose from recycled textiles containing cotton and papers.

• The different way to obtain good quality cellulose from recycled goods.

• The different chemical and mechanical treatments and processes developed for the spinning of the recycled cellulose and our future coagulation pilot line that will be installed close to the carbonization pilot line in Lacq. This new line will help us to improve the performance of the cellulose and to control all the economical aspect.

• The ongoing work to increase the carbonization yield of our precursor without decreasing the mechanical properties, using chemical and mechanical approaches with research on both commercial and new solutions.

• The ongoing computer modelling work to simulate the carbonization static oven and the thermal phenomena around and in the fiber. The main characteristics of the carbonization pilot line.

• Some highlights of industrial scale-up. The material balances and the process block diagrams for cellulose precursor are in the course of being established, through a combination of the laboratory results and the results on the carbonization pilot line and on the future coagulation pilot line.