Orientation Induced Crystallization in Multi-Component Melts Under Flow

流动下多组分熔体的定向诱导结晶

• 批准号: 0906512
• 负责人: Benjamin Hsiao
• 金额: $ 24.4万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0906512&HistoricalAwards=false
• 关键词: Orientation; Induced; Crystallization; Multi; Component

TECHNICAL SUMMARY:The proposed research aims to investigate several newly discovered phenomena of orientation-induced crystallization precursor structures in multi-component polymer melts under flow. The phenomena include (1) formation of precursor structures at both nanoscopic and macroscopic scales, which can act as multi-scaled scaffolds to guide the crystallization process, and (2) the relationships among the flow-induced precursor structures, rheological behavior, multi-component phase behavior and type of flow field. To tackle the proposed problems, following research plans have been composed. First, the chosen multi-component systems, all based on polyolefin will include polymer blends of model compounds (e.g. high molecular weight crystallizable species and low molecular weight non-crystallization species), segmental olefin block copolymers (with only one crystallizable block) and polyolefin nanocomposites with well dispersed surface-modified carbon nanofibers/nanotubes. Second, to understand the rheological behavior, experimental data in dynamic and transient modes will be described by a GEX-based model in order to yield relaxation mechanisms responsible for the formation of precursor structure. Third, the development of structure in real time will be following by the use of combined methods including rheology, in-situ synchrotron small-angle-X-ray scattering (SAXS), wide-angle X-ray diffraction (WAXD) and light scattering techniques. Finally, to understand the effect of different flow fields, results from simple shear (containing the rotational element) and extensional flow (without the rotational element) will be compared.NON-TECHNICAL SUMMARY:The subject of flow-induced crystallization, especially in multi-component systems such as polymer blends, block copolymers and nanocomposites, remains to be one of the most important problems in polymer science and engineering today. With the availability of synchrotron X-ray scattering and diffraction methods, and the coupling of rheology and light scattering techniques, many unanswered questions of fundamental importance can now be suitably addressed. It is known that molecular orientation induced by flow during polymer processing operations can deeply affect the crystallization kinetics as well as the final polymer morphology and properties. The knowledge obtained in the proposed study will significantly enhance our ability to understand the relationships between structure, phase behavior, process and property in multi-component systems containing crystalline components. The information will lead to developments of improved polymer processes and new polymer products, thus benefiting the polymer industry in specific and the society in general. The broader impacts of this proposal are several. The immediate benefit is that the proposed activities will produce tight links between academic and government institutions (i.e., Stony Brook University, National Synchrotron Light Source). Students and scientists will be trained in both institutions and receive interdisciplinary research experiences. They will be exposed to relevant industrial problems and will have a chance to tackle these problems with direct interactions from industrial scientists. They will also be involved in the Stony Brook and Brookhaven National Laboratory summer research programs, where they will supervise high school and undergraduate students as well as industrial scientists to carry out synchrotron X-ray experiments and related in-laboratory studies.

技术摘要：本研究旨在研究流动下多组分聚合物熔体中取向诱导结晶前体结构的几种新发现现象。 这些现象包括（1）在纳米和宏观尺度上形成前体结构，其可以充当多尺度支架来引导结晶过程，以及（2）流动诱导的前体结构、流变行为、多尺度之间的关系。组分相行为和流场类型。为了解决所提出的问题，制定了以下研究计划。 首先，所选择的多组分系统均基于聚烯烃，包括模型化合物（例如高分子量可结晶物质和低分子量非结晶物质）、链段烯烃嵌段共聚物（仅具有一个可结晶嵌段）和聚烯烃的聚合物共混物具有良好分散的表面改性碳纳米纤维/纳米管的纳米复合材料。其次，为了了解流变行为，动态和瞬态模式下的实验数据将通过基于 GEX 的模型进行描述，以便产生负责形成前体结构的弛豫机制。 第三，实时结构的开发将采用流变学、原位同步加速器小角度X射线散射（SAXS）、广角X射线衍射（WAXD）和光散射等组合方法技术。 最后，为了了解不同流场的影响，将比较简单剪切（包含旋转元件）和拉伸流动（不带旋转元件）的结果。非技术摘要：流诱导结晶的主题，特别是在多流场中聚合物共混物、嵌段共聚物和纳米复合材料等组分体系仍然是当今聚合物科学与工程中最重要的问题之一。随着同步加速器 X 射线散射和衍射方法的出现，以及流变学和光散射技术的结合，许多尚未解答的根本性重要问题现在可以得到适当的解决。众所周知，聚合物加工操作过程中流动引起的分子取向可以深刻影响结晶动力学以及最终聚合物的形态和性能。在拟议的研究中获得的知识将显着增强我们理解含有晶体成分的多成分系统的结构、相行为、过程和性能之间关系的能力。 这些信息将促进改进聚合物工艺和新聚合物产品的发展，从而使特定的聚合物行业和整个社会受益。 该提案的更广泛影响是多方面的。 直接的好处是，拟议的活动将在学术机构和政府机构（即石溪大学、国家同步加速器光源）之间建立紧密的联系。学生和科学家将在两个机构接受培训并获得跨学科研究经验。他们将接触到相关的工业问题，并将有机会通过与工业科学家的直接互动来解决这些问题。 他们还将参与石溪和布鲁克海文国家实验室的夏季研究项目，指导高中生和本科生以及工业科学家开展同步加速器 X 射线实验和相关的实验室内研究。