GOALI: To Understand Flow-Induced Crystallization Characteristics of Polyethylene

在这个赠款机会学术联络与工业（GOALI）项目，材料的协调研究将进行。 半结晶聚合物提供由结晶材料赋予的强度和由微晶中精细分散的非结晶区域提供的韧性的高度期望的组合。 这种纳米级复合结构的形态和取向分布决定了最终的材料性能。 这类聚合物能够生产高强度纤维、薄膜和注塑成型部件，广泛用于汽车和生物医学行业。 聚烯烃是占主导地位的半结晶聚合物（每年生产超过1250亿磅），在经济增长和提高生活水平方面发挥着至关重要的作用。 然而，对构成它们的加工-结构-性质关系基础的结构形成的基本理解在很大程度上仍然是一个谜。 加州理工学院和雪佛龙-菲利普斯公司的科学家正在合作，以发现加工历史对聚乙烯微观结构和材料性能的巨大影响的分子基础。 加州理工学院独特的实验能力使在等温条件下精确定义的剪切期间和之后的结构发展的实时观察成为可能。 雪佛龙-菲利普斯公司提供了一系列聚乙烯样品，这些样品涵盖了工业上最重要的分子变量。 这些材料的协调研究将在加州理工学院和雪佛龙-菲利普斯进行，以深入了解流动增强结晶过程中发生的级联事件，这些动力学如何取决于分子属性，以及这些动力学如何与由完全相同的聚乙烯样品制成的吹塑薄膜的结构和机械性能相关。 反过来，从这种大学-工业合作中产生的对加工-结构-性能关系的分子见解可以加速新聚乙烯树脂的开发，以提高生产率和/或上级产品性能。加州理工学院和雪佛龙菲利普斯之间的合作伙伴关系将为研究生和本科生提供共同的指导，将他们的学术培训与工业问题联系起来。

In this Grant Opportunity for Academic Liaison with Industry (GOALI) project, coordinated studies of materials will be conducted. Semicrystalline polymers offer the highly desirable combination of strength conferred by crystalline material and toughness provided by finely dispersed noncrystalline regions among the crystallites. The morphology and orientation distribution of this nano-scale composite structure dictates the ultimate material properties. This class of polymers enables production of high strength fibers, films and injection molded parts widely used from automotive to biomedical industries. Polyolefins are the dominant semicrystalline polymers (over 125 billion pounds produced annually) and play a vital role in economic growth and increased standard of living. Yet the fundamental understanding of structure formation that underlies their processing-structure-property relations remains largely a mystery. Scientists at Caltech and Chevron-Phillips Co. are teaming up to discover the molecular basis of the dramatic effects of processing history on the microstructure and material properties of polyethylene. Unique experimental capabilities at Caltech enable real-time observations of structure development during and after precisely-defined shearing under isothermal conditions. Chevron-Phillips is providing an array of polyethylene samples that span the molecular variables considered most important in industry. Coordinated studies of these materials will be conducted at Caltech and Chevron-Phillips to provide insight into the cascade of events that occur during flow-enhanced crystallization, how these dynamics depend on molecular attributes, and how these dynamics relate to the structure and mechanical properties of blown films made from precisely the same polyethylene samples. In turn, the molecular insights into processing-structure-property relations emerging from this university-industry collaboration can speed development of new polyethylene resins for improved production rates and/or superior product performance. The partnership between Caltech and Chevron-Phillips will provide shared mentorships for graduate and undergraduate students relating their academic training to the industrial issues.