NER: Process for Increasing the Exfoliation and Dispersion of Nano-particles into Polymeric Matrices Using Supercritical Carbon Dioxide

NER：使用超临界二氧化碳增加纳米粒子剥离和分散到聚合物基质中的过程

• 批准号: 0507995
• 负责人: Donald Baird
• 金额: $ 10万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-01 至 2006-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0507995&HistoricalAwards=false
• 关键词: NER; Process; Increasing; Exfoliation; Dispersion

ABSTRACT - 0507995VA Polytechnic Institute & State University NER: Process for Increasing the Exfoliation and Dispersion of Nano-particles into Polymeric Matrices Using Supercritical Carbon Dioxide Background: All the promises and claims that the addition of nano-particles to polymer matrices will miraculously lead to exceptional mechanical, barrier, electrical, and thermal stability properties have not been completely fulfilled because the improvements in properties seem to plateau when reaching levels of about 4 wt%. Only for nylon 6 have levels of 7-wt% been reached before the properties plateau because of hydrogen bonding between the amide groups and the nano-clay particles. The plateau of properties is attributed to the inability to keep the nano-particles exfoliated as the concentration is increased. The three most common methods used to synthesize nano-clay composites, i.e. intercalation of a suitable monomer and subsequent in situ polymerization, intercalation of polymer from solution, and polymer melt intercalation, have not been successful in leading to loading levels greater than about 4 wt%. However, reaching nano-clay particle levels of the order of 10 wt% could lead to a modulus increase of the order of a factor of 5 or more rather than a factor of 1.5 to 2.0(at 4 wt %). Goal: The Goal of this research is to explore the possibility of using supercritical carbon dioxide (sc CO2 ) to increase the level of nano-clay particles which remain exfoliated at levels greater than 5 wt% and preferably as high as 10 wt%. Several previous studies provide evidence that sc CO2 can swell the layered silicates, which thereby may enhance the ease of polymer intercalation into the galleries of the clay. A continuous method is proposed for swelling nano-clays and exfoliating them with sc CO2 and then subsequently injecting the mixture into a molten polymer stream. Furthermore, it is expected that because sc CO2 is highly soluble in a number of polymers it will aid dispersion of the exfoliated clay particles and at same time lower the viscosity of the melt. Once mixing is complete sc CO2 can be extracted from the system leaving the particles dispersed within the thermoplastic. In addition to using microscopy and rheological techniques to identify the degree of exfoliation, mechanical properties of thermoplastic composites will be determined. Intellectual Merit: The concept of a novel, high risk, environmentally benign process for exfoliating and dispersing nano-particles into polymer melts will evolve from this work which should be applicable to a range of nano-particle systems beyond nano-clays and toother polymer matrices. Broader Impact: The approach proposed here is novel and should lead to the filing of a patent application. It has the potential to lead to a signficant increase in the level of nano-partilces and, hence, a significant increase in properties. The increase in properties will extend the range of use of nano-composites especially in the automotive industry and rapid prototyping. The project will initially be one-year duration and, hence, the education of students will have to be planned carefully. However, at least one undergraduate (from an underrepresented group) and a graduate student, who are part of our polymer program, will be exposed to the field of nano-composites and the use of environmentally benign methods for generating improved materials. Furthermore, as part of an interdisciplinary research team, they will learn the importance of a cooperative team effort in solving technical problems. Research Theme (Manufacturing Process): A novel environmentally clean manufacturing process is proposed for generating thermoplastic nano-composite materials with signficantly improved properties.

摘要 - 0507995VA 理工学院和州立大学 NER：使用超临界二氧化碳增加纳米颗粒在聚合物基质中的剥离和分散的过程 背景：所有关于将纳米颗粒添加到聚合物基质中将奇迹般地带来优异的机械、阻隔、电和热稳定性能的承诺和主张尚未完全实现，因为 当达到约 4 wt% 的水平时，性能的改善似乎趋于稳定。 由于酰胺基团和纳米粘土颗粒之间存在氢键，只有尼龙 6 在性能达到稳定水平之前达到了 7 wt% 的水平。性能稳定的原因是随着浓度的增加，纳米颗粒无法保持剥落。 用于合成纳米粘土复合材料的三种最常见的方法，即合适单体的插层和随后的原位聚合、从溶液中插层聚合物以及聚合物熔体插层，尚未成功地导致负载水平大于约4wt%。 然而，达到 10 wt% 左右的纳米粘土颗粒水平可能会导致模量增加 5 倍或更多，而不是 1.5 至 2.0 倍（4 wt% 时）。 目标：本研究的目标是探索使用超临界二氧化碳 (sc CO2 ) 提高纳米粘土颗粒水平的可能性，纳米粘土颗粒保持剥离状态，水平大于 5 wt%，优选高达 10 wt%。 先前的几项研究提供的证据表明，超临界二氧化碳可以使层状硅酸盐膨胀，从而可以提高聚合物嵌入粘土孔道的容易程度。 提出了一种连续方法，用于溶胀纳米粘土并用 sc CO2 剥离它们，然后将混合物注入熔融聚合物流中。 此外，预计由于sc CO2 在许多聚合物中高度可溶，因此它将有助于剥落粘土颗粒的分散，同时降低熔体的粘度。混合完成后，可以从系统中提取 sc CO2，使颗粒分散在热塑性塑料中。除了使用显微镜和流变技术来确定剥落程度外，还将确定热塑性复合材料的机械性能。 智力优点：将纳米颗粒剥落并分散到聚合物熔体中的新颖、高风险、环境友好的工艺概念将从这项工作中发展出来，该工艺应适用于纳米粘土和其他聚合物基质之外的一系列纳米颗粒系统。 更广泛的影响：这里提出的方法很新颖，应该会导致提交专利申请。 它有可能显着提高纳米颗粒的水平，从而显着提高性能。 性能的提高将扩大纳米复合材料的使用范围，特别是在汽车工业和快速成型领域。 该项目最初为期一年，因此必须仔细规划学生的教育。 然而，作为我们聚合物项目的一部分，至少一名本科生（来自代表性不足的群体）和一名研究生将接触纳米复合材料领域以及使用环境友好的方法来生产改进的材料。 此外，作为跨学科研究团队的一部分，他们将了解团队合作在解决技术问题方面的重要性。 研究主题（制造工艺）：提出了一种新颖的环保制造工艺，用于生产性能显着改善的热塑性纳米复合材料。