STTR Phase I: Advanced compatibilization for mixed plastic recycling

这个小企业创新研究第一阶段项目的更广泛影响是促进更多的回收，并使混合废流中最常见的两种聚合物：聚乙烯(PE)和等规聚丙烯(IPP)能够实现升级循环。虽然塑料回收可以帮助缓解巨大的、不断增长的塑料垃圾数量，但混合塑料流--特别是那些含有PE和IPP的塑料流--带来了许多挑战。这些聚合物不相容，但密度相似，不适合简单的熔融混合，但很难分离。虽然已经开发了添加剂来克服不混溶问题，但这些添加剂通常需要在高负荷下添加，并产生机械性能较差的树脂。该项目专注于开发先进的添加剂(相容剂)，可以在低浓度下引入，以生产具有优异的耐久性、延展性和工业实用性的PE/iPP树脂，可与均聚物相媲美或超过均聚物。这种技术有可能为混合回收过程带来更高的效率，推动该领域走向更循环的塑料经济。通过从废气中提供高价值的产品，这项技术的广泛采用将推动塑料废物收集、回收和再制造的改进，支持这些领域和邻近领域的工作。该项目涉及创造非反应性、多接枝共聚物，能够支持高质量的iPP/PE共混物，与目前的树脂相比，具有更好的拉伸强度、抗冲击性和刚性。该方法利用互锁的分子缠结和共结晶来提供对iPP和PE的更强的粘附性。这项技术寻求在PE中使用低至1wt%的添加剂来生产高价值混合材料的能力高达30%的iPP污染。第一阶段的开发将包括：1)优化聚乙烯-接枝-iPP共聚物增容添加剂，2)优化的聚乙烯-接枝-iPP共聚物的放大，3)更大规模的终端聚合物质量测试，以及4)使用不同等级的实际消费后塑料垃圾的组合测试相容剂。这项技术可能有助于更好地了解特定的共聚体系结构如何影响相容效率，同时还满足了支持PE和IPP在混合回收应用中相容的技术需求。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The broader impact of this Small Business Innovation Research Phase I project is to promote increased recycling and to enable the upcycling of two of the most common polymers found in mixed waste streams: polyethylene (PE) and isotactic polypropylene (iPP). While plastic recycling can assist in mitigating the vast and continuously growing volume of plastic waste, mixed plastic streams—notably those with PE and iPP—introduce many challenges. These polymers are immiscible but of similar density, making them unsuitable for simple melt-blending yet difficult to separate. Although additives have been developed to overcome the immiscibility issue, these additives typically need to be added at high loadings and produce resins with poor mechanical properties. This project focuses on the development of advanced additives (compatibilizers) that can be introduced in low concentrations to produce PE/iPP resins with superior durability, ductility, and industrial utility that rivals or outperforms homopolymers. Such a technology has the potential to bring superior efficiency to the mixed recycling process, advancing the field toward a more circular plastics economy. By delivering high-value products from waste streams, widespread adoption of this technology would drive improvements in plastic waste collection, recycling, and re-manufacturing, supporting jobs in these and adjacent fields.This project involves the creation of non-reactive, multi-graft copolymers capable of supporting high-quality iPP/PE blends with superior tensile strength characteristics, impact resistance, and rigidity compared to current resins. The proposed approach leverages interlocked molecular entanglements and co-crystallization to provide stronger adhesion to iPP and PE. This technology seeks capability of up to 30% iPP contamination in PE using as little as 1 wt% additive to generate high-value blended materials. Phase I development will involve: 1) optimization of polyethylene-graft-iPP copolymer compatibilization additives, 2) scale-up of optimized polyethylene-graft-iPP copolymers, 3) testing of larger scale batches for end polymer qualities, and 4) testing of compatibilizers with combinations of different grades of actual post-consumer plastic waste. The technology may contribute to an enhanced understanding of how specific copolymer architectures influence compatibilization efficiency, while also meeting the need for technologies to support compatibilization of PE and iPP for blended recycling applications.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.