Rheological and Architectural Control of Flow-Induced Crystallization

流动诱导结晶的流变学和结构控制

• 批准号: 1067554
• 负责人: Scott Milner
• 金额: $ 36万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-06-01 至 2016-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1067554&HistoricalAwards=false
• 关键词: Rheological; Architectural; Control; Flow; Induced

1067554MilnerPolypropylene (PP), the second-most prevalent synthetic polymer in the world, is used in a vast array of products that are commonplace in daily modern life. In nearly all applications, PP and other semicrystalline polymers are transformed from pellets to a final product in a process that involves melting, flow, and crystallization. Flow-induced crystallization (FIC) makes the processing practical. Imposing a large and sudden shear flow on a cooling melt greatly speeds up crystallization, and profoundly changes the material properties of the final product.This commercially important phenomenon is not well understood. Previous studies have been hampered by the lack of three essential ingredients: the right model polymers, rheology to confirm how flows orient and stretch the polymer chains, and a physics-based theory of crystallization in polymers and how flow affects it. Our proposal combines:1) a unique capability to synthesize PP model combs with controlled architecture; 2) experimental and theoretical expertise in rheology of polymer melts; and 3) a successful theory for nucleation of polymer crystals, which can be extended to address the effects of flow.Graduate students trained in design of PP additives will be in high demand in the US plastics industry in the coming decade. Students supported by this proposal will benefit from collaboration with industrial scientists from ExxonMobil Corporate Research, and international experts at the University of Sheffield. All three PIs worked in industry before coming to Penn State, enabling them to provide their students a strong industrial perspective. As well, this research area offers many opportunities for undergraduate research in synthesis, rheology, and simulations.Leading polyolefin manufacturers are working to develop long chain branched PP (LCBPP) for improved melt processability. Similar architectures are hypothesized to be effective in controlling FIC. Discoveries we make regarding control of FIC can likely be translated to industrial practice.Understanding FIC may be important as well for effective processing of semiconducting and conducting polymers in electronic and photocell applications, where device performance is strongly affected by crystallite size and orientation.

1067554 MilnerPP(PP)是世界上第二流行的合成聚合物，用于日常现代生活中司空见惯的各种产品。在几乎所有的应用中，PP和其他半结晶聚合物在一个涉及熔融、流动和结晶的过程中从颗粒转变为最终产品。流动诱导结晶(FIC)使该工艺实用化。在冷却熔体上施加巨大而突然的剪切流，大大加快了结晶速度，并深刻地改变了最终产品的材料特性。这一重要的商业现象还没有被很好地理解。以前的研究由于缺乏三个基本成分而受到阻碍：正确的聚合物模型，确认流动如何定向和拉伸聚合物链的流变学，以及基于物理的聚合物结晶理论和流动如何影响聚合物结晶。我们的建议结合了：1)独特的合成PP模型梳子的能力和受控结构；2)聚合物熔体流变学的实验和理论专业知识；3)聚合物晶体成核的成功理论，该理论可以扩展到解决流动的影响。受过PP添加剂设计培训的研究生将在未来十年对美国塑料行业的需求很大。这项提议支持的学生将受益于与埃克森美孚企业研究公司的工业科学家和谢菲尔德大学的国际专家的合作。在来到宾夕法尼亚州立大学之前，这三位PI都曾在工业领域工作，这使他们能够为学生提供强大的工业视角。此外，这一研究领域为本科生提供了许多研究合成、流变学和模拟的机会。领先的聚烯烃制造商正在努力开发长链支化PP(LCBPP)，以改善熔体加工性能。假设类似的架构在控制FIC方面是有效的。我们在FIC控制方面的发现很可能转化为工业实践。了解FIC对于电子和光电池应用中半导体和导电聚合物的有效加工也可能是重要的，在这些应用中，器件性能受到微晶尺寸和取向的强烈影响。