2001 TSE: NSF/EPA Partnership for Environmental Research: Source-Based Pollution Prevention through Depolymerization of Poly(ethylene terephthalate) with Carbon Dioxide

2001 TSE：NSF/EPA 环境研究伙伴关系：通过聚对苯二甲酸乙二醇酯与二氧化碳的解聚预防源头污染

• 批准号: 0124618
• 负责人: George Roberts
• 金额: --
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-12-15 至 2007-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0124618&HistoricalAwards=false
• 关键词: 2001; TSE; NSF; EPA; Partnership

Source-Based Pollution Prevention through Depolymerization of Poly (ethylene terephthalate) with Supercritical Carbon DioxideTechnical Description: This research represents a new approach to pollution prevention through elimination of waste polymer that is generated during the manufacture of poly (ethylene terephthalate) (PET). A one-step process will be investigated to depolymerize PET and recover purified monomeric and oligimeric units for repolymerization. The key features of the process are:1) use of a twin-screw extruder to continuously create the fresh surface that is required for a depolymerizing agent (methanol or ethylene glycol) to penetrate into polymer;2) use of supercritical carbon dioxide (scCO2) as a processing aid.Molten polymer is contacted with a mixture of scCO2 and either methanol or ethylene glycol in a twin-screw extruder. The methanol or ethylene glycol causes the PET to depolymerize as it passes through the extruder. The scCO2 plasticizes the PET, facilitating penetration of the methanol/ethylene glycol into the polymer. The scCO2 also reduces the viscosity of the melt and enhances chain mobility, improving the overall reaction rate. Finally, the scCO2 extracts organic contaminants from the polymer. The scCO2 containing dissolved contaminants,unreacted ethylene glycol or methanol, and some of the monomers produced is removed in a vent on the extruder.The potential advantages of this process are:(1) elimination of the solvents and processing steps that otherwise are required for separation of monomers and oligomers from contaminants;(2) much higher depolymerization rates;(3) integration of multiple processes, i.e., depolymerization and extraction, into a single step.The process parameters will be studied include the depolymerizing gent, the depolymerizing agent/polymer ratio, pressure, temperature, CO2/polymer ratio, and average residence time in the extruder.Broader Significance: Approximately 100 million pounds of waste PET is generated annually in U.S. manufacturing facilities. While some of this waste is used in low-value products such as fillers, a large portion remains unusable. Successful development of this new technology could help to solve a serious waste disposal problem and increase the competitiveness of U.S. PET manufacturers. A fundamental understanding of the depolymerization of PET could provide a basis for several technology extensions. First is the application to post-consumer waste PET, the annual volume of which is about 30 times the volume of in-plant waste. Second, this new process should be applicable to other step-growth polymers such as poly (bisphenol A carbonate) and various nylons.

通过超临界二氧化碳解聚聚对苯二甲酸乙二醇酯的源头污染防治技术说明：这项研究代表了一种通过消除聚对苯二甲酸乙二醇酯（PET）生产过程中产生的废弃聚合物来防治污染的新方法。 一个一步的过程将被调查，以脱附PET和回收纯化的单体和低聚物单元的再聚合。 该工艺的主要特点是：1）使用双螺杆挤出机连续产生解聚剂（甲醇或乙二醇）渗透到聚合物中所需的新鲜表面;2）使用超临界二氧化碳（scCO 2）作为加工助剂。熔融聚合物在双螺杆挤出机中与scCO 2和甲醇或乙二醇的混合物接触。 甲醇或乙二醇使PET在通过挤出机时脱附。 scCO 2使PET增塑，促进甲醇/乙二醇渗透到聚合物中。 scCO 2还降低了熔体的粘度并增强了链的流动性，从而提高了总体反应速率。 最后，scCO 2从聚合物中提取有机污染物。 该方法的潜在优点是：（1）消除了溶剂和处理步骤，否则需要从污染物中分离单体和低聚物;（2）高得多的解聚速率;（3）集成多个过程，即，解聚和萃取，成为一个单一的步骤。工艺参数将被研究，包括解聚剂，解聚剂/聚合物的比例，压力，温度，CO2/聚合物的比例，和平均停留时间在挤出机。更广泛的意义：大约1亿磅的废PET每年产生在美国的制造设施。 虽然其中一些废物用于低价值产品，如填料，但很大一部分仍然无法使用。 这项新技术的成功开发将有助于解决严重的废物处理问题，并提高美国PET制造商的竞争力。对PET解聚的基本理解可以为几种技术扩展提供基础。 首先是应用于消费后的PET废料，其每年的体积约为工厂废物体积的30倍。 第二，这种新的工艺应该适用于其他逐步增长的聚合物，如聚（双酚A碳酸酯）和各种尼龙。