Injection molding of post-industrial recycled glass fiber reinforced polyphenylene sulfide (PPS GF40): industrial feasibility and material analysis

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Polymer recycling has become increasingly important in recent decades due to economic and environmental benefits. Recycling provides a cost-saving material supply as well as avoids environmental spillage and enables resource conservation. Quantifying the changes in material properties due to recycling is a key aspect in establishing a circular economy, as it allows understanding the impact of using recycled materials on manufacturing and products. To date, research and industry have investigated the use of recycled materials for commodity and engineering polymers. For high performance plastics, this knowledge exists only at the laboratory scale. The present study comprehensively characterizes the properties of virgin and recycled glass fiber reinforced polyphenylene sulfide (PPS GF40) materials. The materials considered are commercially available to industry, and the recyclates have been reclaimed from post-industrial wastes by the material manufacturers. The results show that as the recycled content increases, the tensile strength of PPS GF40 revealed a similar value for a 50 % recyclate or decreases by 21 % for a regranulate due to both macromolecular shortening and fiber scission. In addition, the shrinkage of each material is quantified. Here, shrinkage increases with increasing result of recycled content. Increasing the amount of recycled material in the compound results in lower process forces in injection molding due to higher melt flow indices. With the help of these results, industrial products may be tailored to meet the properties of recyclate-based materials in order to conserve virgin material resources. In addition, material cost saving potentials are identified by economic calculations based on presently available industrial offers. In the light of the presented results, the introduction of recyclate-based PPS GF40 materials into industrial mass production can be assessed on the basis of mechanical and rheological properties as well as material costs. The overall objective of this study is to provide the aforementioned insights to exploit the economic and environmental benefits of polymer recycling on an industrial scale.