All-lignin carbon fibre composites

Purpose and goal

Purpose: to make a high-performance material from a residual product from the forest industry. Goal 1- Produce a carbon fiber composite entirely from lignin: In principle achieved, apart from the target 30% volume fraction of fibers. Goal 2 - Evaluate the material´s mechanical performance and future potential: Achieved. Objective 3 - Use measured and estimated future properties to see possible future application areas for such a material: Only partially achieved. The mechanical properties are considerably lower than hoped for, mainly due to the low fiber volume fraction.

Expected results and effects

We have made a carbon fiber composite entirely from lignin. A new, completely lignin-based, thermosetting plastic system, currently only available in lab scale, has been used. There are great expectations that its properties can be improved. The mechanical properties are so far insufficient for a structural material. The results are, despite this, unique since a fully lignin-based carbon fiber composite has not been manufactured until now. There is plenty of room for improvement - there are several ideas for approaches - and we believe in this as a material concept for the future.

Planned approach and implementation

The implementation has largely followed plan. Carbon fiber mats were manufactured at RISE. Thermoplastic was manufactured at KTH - Inst. for fiber and polymer technology, and manufacture and tests were made at KTH - Inst. for craft and aircraft. Most work concerned finding a good method for manufacturing the composite; to obtain good wetting, reasonable fiber content and well-consolidated laminates. We have supplemented with rheology measurements. However, no "optimization" of the process has been performed. The mechanical testing was - according to plan - not extensive either.