U.S.-Italy Cooperative Research: Rheology of Liquid Crystalline Polymers

这项美国-意大利奖将支持弗吉尼亚理工学院和州立大学的Donald G. Baird教授和那不勒斯大学的Giuseppe Marrucci教授之间的研究合作。研究人员计划评估现有的描述液晶聚合物（LCP’s）流动行为的分子理论，并在必要时开发替代方法。更具体地说，研究人员计划：(1)评估和测试Doi首先提出的理论，将理论预测与热致性和热致性系统的实验结果进行比较；(2)同时进行流变实验和结构测量，建立应力（变形）与流体结构之间的关系；(3)确定发展反映LCP结构的本构理论的可能方向。具有液晶秩序的高芳族聚酯和聚酰胺引起了相当大的兴趣。高模量纤维和薄膜，在某些情况下注塑件，可以用这些聚合物生产。在这些聚合物的加工过程中，在流动过程中产生的结构和取向在一定程度上是柔性链聚合物所没有的。因此，为了设计液晶聚合物的工艺，有必要建立应力与流动产生的结构之间的关系。通过将美国方面在LCP流变学方面的实验专业知识与那不勒斯大学团队的理论优势相结合，研究人员应该能够更深入地了解LCP的变形与结构之间的关系。

This U.S.-Italy award will support a research collaboration between Professor Donald G. Baird of the Virginia Polytechnic Institute and State University and Professor Giuseppe Marrucci of the University of Naples. The investigators plan to evaluate an existing molecular theory for describing the flow behavior of liquid crystalline polymers (LCP's) and to develop an alternative approach, if necessary. More specifically, the investigators plan to: (1) evaluate and test a theory first proposed by Doi, comparing theoretical predictions with experimental results for both lyotropic and thermo-tropic systems; (2) carry out simultaneous rheological experiments and structural measurements in order to develop relations between stress (deformation) and fluid structure; and (3) determine possible directions for developing constitutive theories reflecting the structure found in LCP's. There is considerable interest in the high aromatic polyestesters and polyamides that exhibit liquid crystalline order. High modulus fibers and films, and in some cases injection-molded parts, can be produced with these polymers. During the processing of these polymers, structure and orientation are generated during flow to a degree not found in flexible chain polymers. Consequently, in order to design processes for liquid crystalline polymers, it is necessary to establish the relation between stress and flow generated structure. By combining the experimental expertise of the U.S. side in understanding the rheology of LCP's with the theoretical strengths of the University of Naples group, the researchers should be able to provide deeper insights into the relation between deformation and structure for LCP's.