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

该奖项为俄克拉何马大学获得用于测量聚合物粘弹性的拉伸流变仪提供了部分支持。该仪器，称为动态机械热分析仪（DMTA），测量存储和损失模量的聚合物范围从刚性玻璃非常灵活的橡胶和粘性熔体。振荡频率和测量温度都可以改变，这使得利用时间-温度叠加构造主曲线成为可能。该仪器还可以进行应力松弛实验，从而确定松弛时间。将购买一个特殊的选项来测量二向色性和双折射性同时与流变性。双折射测量的是片段取向，而二色性测量的是试样中微畴（如球晶）的取向。因此，我们将能够直接将节段取向与弛豫时间、WLF位移常数或活化能联系起来。该仪器将显著改善目前两个不同部门（化学和化学工程）的四名研究人员的研究计划，并将用于启动一个新领域的研究。化学工程学院对填料对聚合物形态的影响很感兴趣。室温弛豫时间与网状掺杂复合材料高温拉伸后的晶体取向有关。该仪器将准确地确定弛豫时间，并允许在不同温度下测量弛豫时间。研究还在进行一种独特的涂层方法，以提高聚合物-填料在复合材料中的附着力。该仪器将有助于确定给定聚合物的最佳涂层。化学工程学院正在研究与生产熔纺和熔喷纤维有关的基本工艺。有了这个仪器，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。光学附着物将用于将流变性能与聚合物链的节段取向相关联。化学系目前正在研究聚合物/盐电解质中的离子传导机制。最广泛的研究涉及聚环氧乙烷/锂系统。DMTA将用于测量机械和弛豫行为的变化，这些变化将与各种光谱确定的盐形态变化相关。其他教员目前正在合成新的本质导电聚合物薄膜。物理性质对最终用途很重要，但样品要么只能作为薄膜（200u）提供，要么作为薄膜使用，并以这种形式进行评估是可取的。最后，计划开展DMTA测量流变特性的研究，同时使用同步辐射测量聚合物晶体的取向行为。%%%***

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.%%%***