Sustainable Manufacturing Of Graphene-Reinforced Polypropylene Composites By Tailoring Compound Properties And Process Techniques

Official URL: https://risc01.sabanciuniv.edu/record=b3205839

Graphene, which attracts the attention of scientists, academia, and industry, is the subject of numerous scientific studies, and in light of graphene's remarkable properties, the field of polymer composites is one of its most highly anticipated applications. However, obstacles such as high cost, sustainability, processability, scaling, serial production, and interphase problems with graphene-based materials need to be optimized to adapt them into polymer compounding processes. Furthermore, according to the production type of graphene, a variety of graphene derivatives exist, such as single-layer graphene, graphene oxide (GO), multilayer GO, reduced graphene oxide (rGO), and graphene nanoplatelet (GNP), which lead to distinctive peculiarities in both graphene quality and the final product. Even though the studies of graphene/polymer composites are escalating in academia and industry, there are deficiencies in the literature on understanding their interactions through the composite constituents, which could be altered by tailoring synthesis routes, modification methods, production techniques, and formulations. Therefore, the main objective of this thesis is to facilitate the adaptation of graphene into commodity polymer composite applications in general and in Polypropylene (PP) composites in particular, based on the circular economy and sustainability issues, by exploring and developing their mechanical, rheological, thermal, and morphological properties. Within this framework, a variety of graphene-based materials, such as electrochemically synthesized GO, waste tire-derived and upcycled GNP, modified GNP, and GNP-coated glass fibers (GFs), were integrated into PP-based composites, blends, and hybrid composites to understand the interactions and compatibility of graphene as well as to tailor polymer processing conditions. This study demonstrated an efficient interface model to develop a scalable methodology of melt-processing of PP with the addition of 1 wt.% GO produced by an improved and eco-friendly electrochemical exfoliation, resulting in a significant enhancement in the mechanical performance of PP composites. In another part of the work, the compatibilizer effect of grafted and recycled GNP with a loading ratio of 0.1 wt.% led to the enhancement of the viscoelasticity performance of PP composites during injection molding. In addition, the interface effect was examined by adjusting the localized regions of GNP within the PP/HDPE blends using comprehensive microscopic techniques. In the last part of the work, a compounding study combined the conventional properties of glass fibers and talc with the superior properties of upcycled GNP to provide lightweight with a 10% weight reduction in the targeted compound formulations. To conclude, several routes were discussed and offered to design and produce stronger, lighter, and novel graphene-based polymer composite materials by enhancing the compatibility and dispersion of fillers in thermoplastic composite systems and integrating them into commercial products with sustainability in mind and environmentally friendly solutions.