INFLUENCE OF THE BINDER ON COMPACTION, SHEAR AND FRICTION FOR CARBON FIBER PREFORMS IN THE RTM-PROCESS

Resin Transfer Molding (RTM) technology has been adapted to various applications to produce high-performance and lightweight carbon fiber reinforced polymers (CFRP) on an industrial scale. Nevertheless, defects due to compaction, such as wrinkles, resin-rich edges, and dry spots, can occur when the mold is closed. This study aims to investigate the binders' influence on friction coefficients, out-of-plane shear stiffness and compressibility to avoid friction-induced compaction defects for carbon fiber preforms using corresponding test rigs in universal testing machines. The results indicate significant differences in compaction and shear behavior for the two different epoxy binders, Epikote and CeTePox, at different levels from 5 % to 8 %. Based on the compaction tests, a dependence of the scatter on the binder content became visible. Interestingly, the binders do not differ much on the bindered 0° layer, but on the unbindered 90° layer. This allows conclusions to be drawn about the degree of binder diffusion through the laminate layers during temperature activation in the preforming process. Based on the compaction tests, a correlation of the scattering with the binder content became visible, which is relevant for ensuring stable performance of the process. The findings from the tests will be further implemented in a compaction simulation for dimensioning the preform and thus the RTM mold.