CAREER: Bridging the Gaps Among Commodity Thermoplastics, Engineering Polymers and Thermosets via Thermally Reversible Crosslinking

职业：通过热可逆交联弥合商品热塑性塑料、工程聚合物和热固性材料之间的差距

• 批准号: 2044877
• 负责人: Muhammad Rabnawaz
• 金额: $ 50.62万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2044877&HistoricalAwards=false
• 关键词: CAREER; Bridging; Gaps; Among; Commodity

Over 70 billion pounds of plastic materials are used each year in the US, but less than 9% of them are recycled. This plastic waste is typically directed to landfills where it poses a threat to the health of the environment. A major reason for this low recycling rate is that these plastic materials are comprised of a variety of chemically distinct polymers that are used for different applications (e.g., commodity, thermosets, and engineering). These polymers are challenging to separate and cost-effectively recycle. For example, 20% of these plastic materials are thermosets, which cannot be recycled by melt-(re)processing methods. This CAREER project aims to investigate a new class of plastic materials (thermally reversible crosslinked polymers) that combines the best qualities of commodity thermoplastics, engineering polymers, and thermosets, while still maintaining their recyclability/melt-(re)processability. The feedstocks for these thermally reversible crosslinked polymers will be polyolefins. Polyolefins account for two-thirds of waste plastics, making them the most abundant and inexpensive plastic found in landfills. This new class of materials will divert discarded plastics from landfills into value-added products (e.g., automotive, aerospace, buildings and infrastructure, utility products, and transportation), thus reducing burdens on landfills and diminishing the leakage of plastics into the environment. The outcome of this proposal will strengthen the domestic (eco)-manufacturing, which will generate a multitude of societal and economic benefits. The research components of this project are integrated with several education and outreach activities that the investigator has developed to prepare a skilled workforce for the US manufacturing sector with a focus on enhancing the participation of women and minority groups in STEM programs. Polyolefins (e.g., polyethylene (PE), polypropylene (PP)) are the least-expensive plastics and account for two-thirds of all polymers produced. However, they also account for more than two-thirds of all plastic waste in landfills. This CAREER proposal aims to investigate and develop novel chemical modification methodologies that will transform discarded PE, PP, and their blends into thermally reversible crosslinked (TRC) polymers. These TRC-polymers will exhibit the desirable qualities of conventional thermosets (solvent resistance, dimensional stability) and engineering polymers (mechanical properties and creep resistance), while still offering comparable processability and recyclability to thermoplastics. Industry-relevant reactive extrusion processes will be used to create TRC-polyethylene (Objective 1), TRC-polypropylene (Objective 2), and TRC-polyolefins (Objective 3) from PE and PP feedstocks. The effects of numerous variables (e.g., melt-processing parameters, nature and amount of reversible crosslinkers, additives, catalysts) on the chemistry and performance of TRC-polymers will be investigated. Advanced spectroscopic, microscopic, and analytical methods will be used to characterize the molecular level chemistry of the TRC-polymers. The physico-mechanical properties such as thermal, solvent resistance, creep resistance, and tensile properties will be validated by standard testing protocols and are expected to be comparable or superior to those of commercial thermosets and engineering polymers. The outcome of this proposed work has the potential to transform the landscape of polymer science and eco-manufacturing by pioneering innovative methods for TRC-polymers. The new knowledge generated through this work will create novel avenues for research in advanced materials and will transform the fields of additive manufacturing, sustainable manufacturing, and offer unique feedstock materials for high-performance composites, foams, and melt-(re)processable interpenetrating networks. In addition, the development of a highly skilled future workforce is an integral part of this research which will be accomplished via training opportunities for undergraduate and graduate students, industry-academia collaboration, and creating an advanced curriculum. Outreach programs for K-12 students as well as training opportunities for high school teachers are planned to inspire young students towards STEM careers. A focus will be on the inclusion of programs that foster the participation of women and minorities in STEM programs. During this project, the future workforce will be educated and equipped to understand and appreciate emerging technological advances, thus strengthening the US sustainable manufacturing sector.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.

美国每年使用超过700亿磅的塑料材料，但其中只有不到9%被回收利用。这些塑料垃圾通常被送往垃圾填埋场，对环境健康构成威胁。回收率这么低的一个主要原因是这些塑料材料是由各种化学上不同的聚合物组成的，这些聚合物用于不同的应用（例如，商品、热固性塑料和工程）。这些聚合物的分离和回收具有成本效益。例如，这些塑料材料中有20%是热固性的，不能通过熔融（再）处理方法回收。这个CAREER项目旨在研究一种新型塑料材料（热可逆交联聚合物），它结合了商品热塑性塑料、工程聚合物和热固性的最佳品质，同时仍保持其可回收性/熔融（再）加工性。这些热可逆交联聚合物的原料将是聚烯烃。聚烯烃占废塑料的三分之二，使它们成为垃圾填埋场中数量最多、价格最便宜的塑料。这种新型材料将把废弃塑料从垃圾填埋场转移到增值产品（例如，汽车、航空航天、建筑和基础设施、公用事业产品和运输），从而减轻垃圾填埋场的负担，减少塑料泄漏到环境中。该提案的结果将加强国内（生态）制造业，这将产生大量的社会和经济效益。该项目的研究部分与研究者开发的几项教育和外展活动相结合，旨在为美国制造业准备一支熟练的劳动力队伍，重点是提高妇女和少数群体在STEM项目中的参与度。聚烯烃（如聚乙烯（PE）、聚丙烯（PP））是最便宜的塑料，占所有聚合物产量的三分之二。然而，它们也占了垃圾填埋场所有塑料垃圾的三分之二以上。本CAREER提案旨在研究和开发新的化学改性方法，将废弃的PE， PP及其共混物转化为热可逆交联（TRC）聚合物。这些trc聚合物将表现出传统热固性（耐溶剂性，尺寸稳定性）和工程聚合物（机械性能和抗蠕变性）的理想品质，同时仍然提供与热塑性塑料相当的可加工性和可回收性。工业相关的反应挤出工艺将用于从PE和PP原料中生产trc -聚乙烯（目标1）、trc -聚丙烯（目标2）和trc -聚烯烃（目标3）。将研究许多变量（如熔融加工参数、可逆交联剂的性质和数量、添加剂、催化剂）对trc聚合物的化学和性能的影响。先进的光谱、显微镜和分析方法将用于表征trc聚合物的分子水平化学。物理机械性能，如耐热性、耐溶剂性、抗蠕变性和拉伸性能将通过标准测试方案进行验证，预计将与商业热固性和工程聚合物相当或更好。这项工作的结果有可能通过开拓trc聚合物的创新方法来改变聚合物科学和生态制造的格局。通过这项工作产生的新知识将为先进材料的研究创造新的途径，并将改变增材制造、可持续制造领域，并为高性能复合材料、泡沫和可熔融（再）加工互穿网络提供独特的原料材料。此外，培养高技能的未来劳动力是这项研究的一个组成部分，这将通过为本科生和研究生提供培训机会、产学研合作和创建高级课程来实现。针对K-12学生的拓展项目以及为高中教师提供的培训机会，计划激励年轻学生从事STEM职业。重点将是纳入促进妇女和少数民族参与STEM项目的项目。在这个项目中，未来的劳动力将接受教育和装备，以理解和欣赏新兴的技术进步，从而加强美国的可持续制造业。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。