Microrecycling solution for conversion of waste plastics into high quality products using available machinery

Plastic revolutionised the world, but meantime generates a substantial amount of waste plastics. However, plastics are generally non-biodegradable and hence remain in the environment for a very long time. Most plastics are not discarded properly, these wastes either end up in the landfills or left in the environment which can end up in water systems including oceans. Alternatively, plastics are burned to remove from premises or to recover energy. Today it is well established that if waste plastics are not deal properly, they can pose a great risk to both the people and the environment and at the same time a lot of valuable materials will be lost. However, only a small percentage of waste plastic is currently recycled due to the limitations of recycling and reprocessing technology, which requires massive infrastructure and normally is not economically feasible and environmentally sustainable. To overcome these challenges, several easy-to-operate and less cost incentive processes have been evaluated throughout this PhD project. This project first began by investigating the effect of reprocessing on polymer, which is important to develop efficient and effective recycling processes. At the next step a simple process that required fewer steps has been developed to utilise waste hard plastics as feedstock to produce new plastic products whilst retaining the original properties and colour of input waste plastics. Then, two novel processes have been demonstrated for another two types of problematic waste plastic (fishing net and flexible plastic packaging). In the final part of this research, three-dimensional (3D) printing, an advanced method of manufacturing, has been employed to transform waste plastics from toys into products. All produced plastics from the proposed methods showed good mechanical performances as virgin material. Life cycle assessment indicated that the processes could reduce greenhouse gas emission, fossil fuel depletion and ecotoxicity. Considering the conclusions of this project, different methods demonstrated in this thesis can manage and transform a wide range of waste plastics (from hard to soft) into high-quality plastics. They are not limited to the case studied waste plastics rather they have the potential to deal with other similar kinds of waste plastic. Overall, this research will create value for waste plastics, and in turn, speed up their collection and recycling