Light and X-ray Scattering of Heat Treated Thermotropic Polymers

摘要

Thermotropic liquid crystalline polymers (LCPs) display remarkable physical properties including tolerance for high temperatures, resistance to chemicals and acids, and high tensile strength1-4. These properties make them ideal for applications into the electronics, medical, dental, automotive and aerospace industries5. Thermotropic LCPs are wholly aromatics, i.e., there are not flexible spacers in the backbone (for instance, methylene CH2 groups). Manipulating the orientation of the anisotropic macromolecules optimizes mechanical properties of LCP fibers1. Molecular alignment and microstructure are controlled through processing conditions during fiber spinning1 and heat treatment6-12. Mechanical modulus, molecular weight and thermal transition temperatures can be increased through prolonged thermal treatments (Calundann and Jaffe1, Romo-Uribe et al11, 12, Chung et al6; Kordestani et al8,9), and attempts have been made to correlate the mechanical properties with the molecular structure 8. In this work the influence of heat treatment on the texture, microstructure and tensile mechanical properties of extruded thin films of a series of high-performance thermotropic liquid crystal polymers (LCPs) was investigated.