Nowadays, the use of fiber reinforced polymers increases continuously. Endless carbon fiber reinforced polymers are used primarily for products, which require high stiffness and strength while having a minimum weight. The increasing use of these materials results in the issue of production and after lifetime waste recycling. Due to the high costs for carbon fibers the recycling is reasonable from the economic point of view. Currently there are different strategies to reuse carbon fibers. One of them is processing carbon fiber waste in twin screw compounders for the production of short fiber reinforced polymers. One of the main issue during this process is the distributive mixing of the fibers and the fiber degradation of carbon fiber waste which is mostly available as cutted fabric.
In order to achive higher fiber lengths while having evenly distributed fibers in the polymer matrix, a new type of compounding machine typically used for recycling of domestic plastic waste is investigated. In a first step the flow region of the machine is calculated numerically. With a particle tracking method that is based on the numerical flow calculation the distributive mixing behavior is determined. In the experimental part the compounding of glass fibers (chopped strands) in a Polypropylene matrix is investigated. Different pre-mixtures of granulate and fibers with fiber proportions of 20%, 30% and 40% are prepared and processed using different parameter settings. For every processing point the fiber length distribution and the fiber mass proportion in the produced granulate is measured. By analyzing the different results the homogeneity and the fiber breakage is determined. Finally there is a comparison between the material properties of the conventionally produced material in the twin screw process and the material produced with the aforementioned machine.