Recycling and upgrading of glass fiber reinforced polypropylene composites

Examensarbete för masterexamen
Hansson, Charlie
Larsson, Oscar
With increased societal awareness, an emphasis has been created over the need for sustainable, circular solutions. The automotive industry has tried to address these concerns with an increased focus on the end-of-life of vehicles. Mechanical recycling of components has been one of the routes of interest that has been highlighted in this work where newly produced instrument panel carriers produced by Volvo Cars, made of 20 % glass fiber-reinforced polypropylene composites, were recycled three times to study the effect of the processing on mechanical properties. The instrument panels were mechanically recycled by milling, compounding and subsequently injection moulding into test bars. Fiber lengths were measured after each processing step, and the mechanical properties were evaluated. The length of the glass fibers reduced after each processing step, especially after compounding, along with a reduction in all mechanical properties. To restore some of the properties lost during recycling, an upgrading step was investigated. In this step, the recycled instrument panels were upgraded in separate batches by adding three types of additional glass fibers: virgin fibers, post-industrial residual glass fibers, and post-consumer residual glass fibers, respectively. Two different types of impact modifiers were also tested. In addition, an instrument panel carrier from an end-of-life vehicle was also recycled once to observe its mechanical properties and compare it to the newly produced instrument panel carrier processed in a similar manner. The results showed similar mechanical properties, except that the end-of-life panel had a lower strain at break. An oxidative-induction time (OIT) measurement also showed a lower level of antioxidants, and an oxidative-induction temperature measurement showed a higher degree of matrix degradation in the end-of-life panel. The study found that recycled glass fiber-reinforced polypropylene can be re-used and made into new useful products with small additions of new material, such as virgin glass fiber or impact modifiers. Further research into the subject should study the effects of the interface between recycled glass fibers and the polymer matrix, as these results were below expectations in this study
Glass fiber, Polypropylene, Recycling, Upgrading, Impact modifier
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