Crystallization of Polymers and Copolymers at Very High Supercoolings

聚合物和共聚物在极高过冷度下的结晶

• 批准号: 0096505
• 负责人: Joseph Spruiell
• 金额: $ 30万
• 依托单位: University of Tennessee Knoxville
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-02-01 至 2005-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0096505&HistoricalAwards=false
• 关键词: Crystallization; Polymers; Copolymers; Very; Supercoolings

The solidification of polymers and copolymers under conditions relevant to industrial processing operations is of considerable importance to the design of polymers and to operation of the plastics industry in all its forms. One of the most sought after conditions is crystalline polymers cannot be studied at high supercoolings, or low temperatures as the polymers usually solidify before the desired isothermal condition can be achieved. Two of those polymers are linear polyethylene and nylon 66. The recently developed Ding-Sprueill method of rapid cooling which utilizes a micro-thermocouple embedded in the sample and direct continuous measurement of temperature has proved to over come the difficulties in an unexpected way. As the polymer film is cooled rapidly the heat of crystallization maintains the polymer at a constant temperature determined by the relative rates of cooling and heat liberation. The proposed research seeks to continue current successful studies of polyethylene and its copolymers, which have led to the discovery of new laws of polymer crystallization. These laws have not been observed previously experimentally, nor are they predicted by any available theories. It is proposed additionally to apply the method to nylon 66 and its copolymers. The P.I's group, under current NSF support, have shown that nylon 66 and its copolymers do not follow secondary nucleation as the mechanism of crystal growth, unlike other polymer systems. They therefore compose a unique group of polymers that follow surface roughening as the mechanism of growth. The proposed research is intended to shed considerable light on the mechanism of crystallization of these two generic forms of interest to basic physics, assist in resolving several current controversies on mechanisms of crystallization, and at the same to generate understanding of the crystallization behavior of two very important industrial polymers under conditions which are directly applicable to manufacturing operations. Experimentation will include studies of detailed morphologies developed over wide crystallization temperature ranges under conditions hitherto unattainable as well as studies of the crystallization kinetics and the melting behavior. Experimental methods to be used include transmission electron microscopy, atomic force microscopy, optical microscopy, small angle x-ray scattering and small angle neutron scattering.%%%This research is in the area of structure, crystallization and processing of industrially important polymeric materials.

聚合物和共聚物在与工业加工操作有关的条件下的固化对聚合物的设计和各种形式的塑料工业的操作具有相当重要的意义。最受追捧的条件之一是结晶聚合物不能在高过冷或低温下进行研究，因为聚合物通常在达到所需的等温条件之前凝固。其中两种聚合物是线性聚乙烯和尼龙66。最近发展的Ding-Sprueill快速冷却方法利用嵌入在样品中的微型热电偶和直接连续测量温度，以一种意想不到的方式克服了困难。当聚合物薄膜迅速冷却时，结晶热使聚合物保持在由冷却和热释放的相对速率决定的恒定温度。拟议的研究旨在继续目前成功的聚乙烯及其共聚物的研究，这些研究已经发现了聚合物结晶的新规律。这些定律以前没有在实验中被观察到，也没有任何现有的理论预测到。此外，还建议将该方法应用于尼龙66及其共聚物。在国家科学基金会的支持下，p.i.的小组已经证明尼龙66及其共聚物不像其他聚合物系统那样遵循二次成核的晶体生长机制。因此，它们组成了一组独特的聚合物，遵循表面粗糙作为生长机制。提出的研究旨在阐明这两种对基础物理学感兴趣的一般形式的结晶机制，协助解决当前关于结晶机制的几个争议，同时产生对两种非常重要的工业聚合物在直接适用于制造操作的条件下的结晶行为的理解。实验将包括在迄今为止无法达到的条件下在宽结晶温度范围内发展的详细形态研究，以及结晶动力学和熔化行为的研究。实验方法包括透射电子显微镜、原子力显微镜、光学显微镜、小角x射线散射和小角中子散射。这项研究是在结构，结晶和工业上重要的聚合物材料的加工领域。