Some Modern Aspects of Elastomer Science and Technology

提出的研究的一个实际目标是获得可用于优化弹性体材料的性能的结构-性能关系。例如，应力-应变结果的各种弹性体材料的伸长率，双轴拉伸，剪切和扭转将解释使用两个分析理论的基础上纠缠约束网络连接，和计算机模拟。弹性体将包括通过工业中使用的一些相对不受控制的技术交联的商业上重要的聚合物，但也包括制备成具有不寻常的双峰链长分布的一些弹性体，其通过末端连接官能封端的聚合物链来改善最终性能。另外的弹性体将在提供具有一些不寻常的优点的结构的条件下生产，例如通过在溶液中或在应变状态下交联。对这些材料的实验是特别感兴趣的，将是确定最大延伸率和韧性的应力-应变测量。弹性体凝胶将用于生产增强取向和改善机械性能的可生物降解薄膜。第二个主要的主题涉及弹性体中的应变诱导结晶，在伸长率，但也在几个重要的变形中，结果几乎完全缺乏。一些分析理论和计算机模拟将进行平行调查。新型增强填料如二氧化硅将通过前体如有机硅酸盐和简单金属盐如氯化铁的水解原位产生。特别重要的是确定最大化增强的颗粒尺寸，并表征颗粒形状和非球形颗粒取向的影响。新型材料将通过用一种类型的陶瓷涂覆另一种类型的颗粒来制备。还可以将弹性体链穿过增强沸石。所得填料增强弹性体的特征主要在于机械性能测量，电子显微镜，X射线和中子散射，和脉冲传播测量。还将进行模拟，以阐明一般填充弹性体的增强机制。作为最后一个主题，将进行实验，以利用弹性域的能力，以提高聚合物-陶瓷混杂复合材料的耐冲击性，其中陶瓷是连续相。这里特别令人感兴趣的是通过使用其中一个相中的网络结构的连通性来控制分散水平，以“挫败”不同的双组分系统中的通常类型的相分离。包括开发一个关于弹性体和橡胶类弹性的模块，用于在“移动的实验室”中部署，以便将科学和工程演示和实验带到K-辛辛那提的12个学生。三个大型的“温尼贝戈”大小的移动的教室正在配备，每个教室都将配备必要的设备，让学生有机会进行比通常在典型的K-12场地更先进的实验。

One practical goal of the research proposed is to obtain structure-property relationships that can be used to optimize the properties of elastomeric materials. For example, stress-strain results on a variety of elastomeric materials in elongation, biaxial extension, shear, and torsion will be interpreted using both analytical theories based on entanglement-constrained network junctions, and computer simulations. Elastomers will include both commercially important polymers cross linked by some of the relatively uncontrolled techniques used in the industry, but also some elastomers prepared to have unusual bimodal chain-length distributions that improve ultimate properties by end linking functionally-terminated polymer chains. Additional elastomers will be produced under conditions giving structures that have some unusual advantages, for example by cross linking in solution or in a state of strain. Experiments on these materials that are of particular interest will be stress-strain measurements for identifying maximum extensibilities and toughness. Elastomeric gels will be used to produce biodegradable films of enhanced orientation and improved mechanical properties. The second major topic involves strain-induced crystallization in elastomers, in elongation, but also in several important deformations in which results are almost entirely lacking. Some analytical theory and computer simulations will be carried out in parallel investigations. Novel reinforcing fillers such as silica will be generated in-situ by hydrolyses of precursors such as organosilicates, and simple metal salts such as ferric chloride. Of particular importance will be identifying the particle size that maximizes reinforcement, and characterizing the effects of particle shape and the orientations of non-spherical particles. Novel materials will be prepared by coating particles of one type with a ceramic of another type. It will also be possible to thread elastomeric chains through reinforcing zeolites. The resulting filler-reinforced elastomers will be characterized primarily by mechanical property measurements, electron microscopy, X-ray and neutron scattering, and pulse-propagation measurements. Simulations will also be carried out to elucidate reinforcing mechanisms in filled elastomers in general. As a final topic, experiments will be carried out to exploit the ability of elastomeric domains to improve the impact resistances of polymer-ceramic hybrid composites in which the ceramic is the continuous phase. Of particular interest here is control of the level of dispersion by using the connectivity of networks structures in one of the phases to "frustrate" the usual types of phase separation in disparate two-component systems.Broader impacts, described within the proposal, include developing a module on elastomers and rubberlike elasticity for deployment in a "Mobile Laboratory" to bring science and engineering demonstrations and experiments to K-12 students in Cincinnati. Three large "Winnebago" sized mobile classrooms are being outfitted, and each will be stocked with the equipment necessary to allow students the opportunity to carry out more advanced experiments than usually possible in typical K-12 venues.