Structure-Rheology-Domain Texture Relationships in Thermotropic Liquid-Crystalline Polymers

热致液晶聚合物中的结构-流变-域织构关系

• 批准号: 9320351
• 负责人: Chang Han
• 金额: $ 16.49万
• 依托单位: University of Akron
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-10-01 至 1997-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9320351&HistoricalAwards=false
• 关键词: Structure; Rheology; Domain; Texture; Relationships

ABSTRACT CTS-9320351 University of Akron P.I.: Chang D. Han It is proposed to investigate structure-rheology-domain texture relationships in thermotropic liquid-crystalline polymers (TLCPs). For the investigation, a homologous series of aromatic homopolyester, poly (phenylsulfonyl)-p-phenylene bis(4-oxybenzoate) with methylene units (CH2)n as flexible spacers (PSHQ), will be synthesized via solution polymerization. On the basis of the preliminary study performed by the principal investigator who used decamethylene (CH2)10 as flexible spacers, PSHQ can be used as a model compound to study structure-rheology-domain texture relationships in TLCP because, owing to its relatively low clearing temperature, PSHQ allows one to control the initial condition (i.e., initial domain texture) by first heating to an isotropic state and then cooling slowly down to an anisotropic state. In the synthesis of PSHQ the number of methylene units (i.e., n=7-16) will be varied, in order to investigate the effect of flexible spacer, especially the so-called 'odd-even' effect, on the resulting rheological behavior and domain texture in the specimen. The major thrust of the proposed research project is to enhance our understanding as to how the domain texture of TLCP, which depends on both thermal and shear histories, influences its rheological behavior, which in turn is affected by the orientational order of the polymer. Therefore we propose to conduct, with emphasis on the 'odd-even' effect, the following investigations: (1) A rheo-optical study will be conducted to understand the relationship between the rheological behavior and the flow-induced textures of PSHQ; (2) The domain size and its distribution in PSHQ specimen will be determined, via image analysis, under well-controlled annealing conditions; (3) The orientational order parameter of PSHQ specimens will be determined, via solid-state nuclear magnetic resonance spectroscopy, as a function of temperature; (4) The persistence length of PSHQ will be determined using dynamic light scattering; (5) An expression for the excluded volume (intermolecular) potential will be developed for PSHQ; and (6) The rheological behavior of PSHQ will be predicted by numerically solving the Doi Kinetic equation, by using the expression for the excluded volume potentia, which is to be developed in the proposed study.

摘要CTS-9320351阿克伦大学P.I.： 张D韩 研究了热致液晶聚合物（TLCPs）的结构-流变-畴织构关系。 为了研究，将通过溶液聚合合成具有亚甲基单元（CH 2）n作为柔性间隔基的芳香族均聚酯，聚（苯磺酰基）-对苯撑双（4-羟基苯甲酸酯）（PSHQ）。 在使用癸亚甲基（CH 2）10作为柔性间隔基的主要研究者进行的初步研究的基础上，PSHQ可以用作模型化合物来研究TLCP中的结构-流变学-结构域织构关系，因为PSHQ由于其相对低的澄清温度，允许人们控制初始条件（即，初始畴结构），然后缓慢冷却到各向异性状态。 在PSHQ的合成中，亚甲基单元的数目（即，n=7-16），以研究柔性间隔物的影响，特别是所谓的“奇-偶”效应，对样品中所得的流变行为和域织构的影响。 建议的研究项目的主要推力是提高我们的理解，TLCP的域纹理，这取决于热和剪切历史，影响其流变行为，这反过来又是由聚合物的取向顺序的影响。 因此，我们提出了以“奇-偶”效应为重点，进行以下研究：（1）进行流变-光学研究，以了解PSHQ的流变行为与流动诱导织构之间的关系：（2）通过图像分析，在良好控制的退火条件下，确定PSHQ试样中的畴尺寸及其分布;（3）通过固态核磁共振谱确定PSHQ样品的取向有序参数作为温度的函数;（4）使用动态光散射确定PSHQ的持久长度;（5）排除体积的表达式（6）通过数值求解Doi动力学方程，使用在拟议研究中开发的排除体积势的表达式，预测PSHQ的流变行为。