Acquisition of Tensile Rheometer for the Simultaneous Measurement of Viscoelastic and Optical Properties of Polymer Solids

获得拉伸流变仪以同时测量聚合物固体的粘弹性和光学性质

• 批准号: 9802776
• 负责人: Brian Grady
• 金额: $ 7.5万
• 依托单位: University of Oklahoma Norman Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-08-15 至 1999-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9802776&HistoricalAwards=false
• 关键词: Acquisition; Tensile; Rheometer; Simultaneous; Measurement

9802776GradyThis award provides partial support for the University of Oklahoma to acquire a tensile rheometer for the measurement of polymer viscoelastic properties. This instrument, termed a dynamic mechanical thermal analyzer (DMTA), measures storage and loss moduli for polymers ranging from stiff glasses to very flexible rubbers and viscous melts. Both the requency of oscillation and the measurement temperature can be varied, which enables the construction of master curves using time-temperature superposition. This instrument can also perform stress relaxation experiments permitting the determination of relaxation times. A special option will be purchased to measure the dichroic and birefringent properties simultaniously with the rheological properties. Birefringence measures segmental orientation, while dichroism measures orientation of microdomains, such as spherulites, in the specimen. Hence we will be able to directly correlate segmental orientation with relaxation times, WLF shift constants, or activation energies.This instrument will significantly improve the current research programs of four investigators in two different departments (Chemistry and Chemical Engineering) and will also be used to initiate research in a new area. Faculty in Chemical Engineering are interested in the effect of fillers on polymer morphology. Room temperature relaxation times have been correlated with crystallite orientation after stretching at elevated temperatures in reticulate doped composites. This instrument will accurately determine relaxation times and also allow the measurement of relaxation times at different temperatures. Studies are also underway on a unique coating method that improves polymer-filler adhesion in composites. This instrument will help identify the optimal coating for a given polymer. Faculty in Chemical Engineering are conducting studies of fundamental processes associated with producing both melt-spun and melt-blown fibers. With this instrument, they will be able to more fully characterize the fibers to better understand the relationship between processing and properties. The optical attachment will be used to correlate rheological properties with segmental orientation of polymer chains. Faculty in Chemistry are presently investigating mechanisms of ionic conduction in polymer/salt electrolytes. The most extensive studies have involved poly(ethylene oxide)/lithium systems. The DMTA will be used to measure changes in mechanical and relaxation behavior and these changes will be correlated with changes in salt speciation determined by various spectroscopies. Other faculty currently synthesize novel intrinsically electrically conducting polymer films. Physical properties are important to end use but samples are either only available as thin films (200 u) or the use of interest is as thin films and evaluation in that form would be desirable. Finally, it is planned to initiate studies to measure rheological properties using the DMTA while simultaneously measuring the orientation behavior of polymer crystallites using synchrotron radiation.%%%***

9802776该奖项为俄克拉荷马大学购买用于测量聚合物粘弹性性质的拉伸流变仪提供部分支持。该仪器被称为动态机械热分析仪(DMTA)，可测量从硬质玻璃到非常柔软的橡胶和粘性熔体等各种聚合物的存储和损耗模数。振荡频率和测量温度都可以改变，这使得可以使用时间-温度叠加来构建主曲线。该仪器还可以进行应力松弛实验，从而确定松弛时间。将购买一种特殊的选项，以同时测量二向色性和双折射性质以及流变性质。双折射测量的是节段取向，而二向色性测量的是样品中微区的取向，如球晶。因此，我们将能够直接将片段取向与弛豫时间、WLF位移常数或激活能相关联。该仪器将显著改善两个不同系(化学和化学工程)的四名研究人员目前的研究计划，并将用于启动一个新领域的研究。化学工程系对填料对聚合物形态的影响很感兴趣。在网状掺杂复合材料中，室温弛豫时间与高温拉伸后的微晶取向有关。该仪器将准确地确定松弛时间，并允许测量不同温度下的松弛时间。一种独特的涂层方法也在研究中，这种方法可以提高复合材料中聚合物-填料的附着力。该仪器将帮助确定特定聚合物的最佳涂层。化学工程系正在对与生产熔纺和熔喷纤维相关的基本工艺进行研究。有了这台仪器，他们将能够更全面地表征纤维，以更好地了解加工和性能之间的关系。光学附件将用于将流变特性与高分子链的链段取向相关联。化学系目前正在研究聚合物/盐电解液中的离子传导机制。最广泛的研究涉及聚环氧乙烷/锂体系。DMTA将被用来测量机械和松弛行为的变化，这些变化将与各种光谱确定的盐形态的变化相关联。其他学院目前正在合成新型本征导电聚合物薄膜。物理性能对最终用途很重要，但样品只能以薄膜(200u)的形式提供，或者感兴趣的用途以薄膜的形式存在，需要以这种形式进行评估。最后，计划启动使用DMTA测量流变性的研究，同时使用同步辐射测量聚合物微晶的取向行为。