Developing structure-property-performance relationships in recycled polymer thermoplastics to help enable the increased recycling of plastic waste

近年来，塑料污染问题越来越成为各政党、非政府组织、慈善机构和市场领先企业的议程。可持续性比以往任何时候都更加重要，所谓的“塑料污染之战”正处于历史最高水平，关于这一问题的监管立法机构越来越多，最引人注目的是英国政府于2022年4月开始征收塑料包装税。许多行业严重依赖聚合物热塑性塑料的使用，包括汽车、食品和饮料、建筑、农业和消费品行业。由于我们在日常生活中如此严重地依赖这些材料，期望在短期内完全、永久地摆脱塑料的使用是不现实的。因此，发展其他废物管理途径至关重要。目前，机械回收为解决消费塑料垃圾问题提供了最可行、最大规模的解决方案。随着人们在日常生活中选择更加环保的选择，循环塑料经济的要求比以往任何时候都更加适用。然而，这一进展需要深入了解再生塑料的掺入如何影响塑料产品质量，以及含有再生材料的产品在整个生命周期中的表现。这项研究对于确保循环塑料倡议的实现至关重要，同时也是塑料废物问题的长期解决方案。经过回收的塑料不仅包括消费后塑料包装，而且由于这是聚合物热塑性塑料的最大部门，因此该领域的研究具有最直接的重要性。实现由高重量百分比的再生塑料制成的产品的高质量和性能是说服世界改用再生材料的关键。工业需要一致性和高质量的原料，以确保高标准的最终产品-因此，目前对从化石燃料中提取的原生塑料的需求很高。为了满足这些需求，对再生聚合物热塑性塑料的研究是强调回收过程如何影响材料结构和性能的关键。目前，关于塑料材料在多次回收循环后如何变化和表现的深入信息有限，需要在该领域开展广泛的工作，以帮助实现循环经济。这项博士研究的目的是在广泛的机械回收之后，对聚合物热塑性塑料的结构、性能和性能之间的联系有一个强有力的理解。对这些结构-性能-性能关系的理解将有助于推动由完全回收原料制成的材料的明智设计。目前，增加材料中可回收成分的问题仅受到“低质量”产品的限制。通过研究如何提高回收材料的性能来改变这种看法，解决了严重依赖原生塑料聚合物的问题。通过提供知情的设计研究，工业供应商和制造商可以在产品设计期间参考这些信息，以确保包括高浓度的回收材料，促进更广泛地将回收塑料纳入消费市场。

In recent years, the issue of plastic pollution climbed further and further up the agendas of political parties, NGOs, charities and market leading businesses. Sustainability is more important than ever, and the so called 'war on plastic pollution' is at an all-time high, evidenced by the growing amount of governing legislature released on the issue, most notably the introduction of a plastic packaging tax in April 2022 by the UK government. A number of sectors rely heavily on the use of polymer thermoplastics including the automotive, food and beverage, construction, agriculture and consumer goods industries. With such a heavy reliance on these materials in day to day life, it is unrealistic to expect a complete, permanent shift away from the use of plastics in the short term. It is therefore vital to develop other waste management avenues. Currently, mechanical recycling offers the most viable and large scale solution to solve the issue of consumer plastic waste. With people choosing to make more environmentally minded choices in day to day life, the requirement of a circular plastics economy is more applicable than ever before. However, this progression requires in depth knowledge of how the incorporation of recycled plastic affects plastic product quality but also how products containing recycled material perform across their whole life-cycle. This research is critical in ensuring that the circular plastics initiative is achievable but also acts as a long term solution to the problem of plastic waste. The plastics which undergo recycling do not just include post-consumer plastic packaging but as this is the largest sector for polymer thermoplastics, research in this field holds the most immediate importance. Achieving high quality and performance of products made from high weight percentage recycled plastic is key in convincing the world to swap to recycled materials. Industry demands consistency and a high quality of material feedstock to ensure a high standard of final product - hence the current high demand on virgin plastics derived from fossil fuels. In order to meet these demands, the research carried out on recycled polymer thermoplastics is key in highlighting how the recycling process affects the structure and properties of materials. In depth information on how plastic materials change and perform following multiple recycling cycles is currently limited and extensive work in the field is required to help achieve a circular economy. This PhD research aims to develop a robust understanding of the link between structure, property and performance of polymer thermoplastics following extensive mechanical recycling. An understanding of these structure-property-performance relationships will help to drive the informed design of materials made from an entirely recycled feedstock. Currently, the issue of increasing recycled content in materials is only limited by the perceived 'lower quality' product that is presented. By changing this perception through research into how the performance of recycled material can be improved, the issue of heavy reliance on virgin plastic polymer is addressed. By providing informed design based research, industrial suppliers and manufacturers can consult this information during product design to ensure high concentrations of recycled material are included, facilitating a more widespread incorporation of recycled plastics into the consumer market.