Study On Preparation And Properties Of Liquid Crystal Polymer/Carbon Nanotube Composites

Liquid crystal polymers include thermotropic liquid crystal polymer (TLCP) and lyotropic liquid crystal (LLCP). They have highly molecule alignment, high modulus and very fillers, so they have been extensively applied. But they have many defects, such as, not easily process, too high use temperature, response time too slow, and so on, so we must modify them. In recently, Liquid crystal polymer/carbon nanotubes composites are one of the most hotspots for modifying them. In this paper, we prepared two types of liquid crystal polymer/carbon nanotubes, and characterized them.The thesis consists of three chapters:Chapter 1 served as an overview of the study. And detailed reviews of the Liquid crystal polymer/carbon nanotubes composites were introduced. In the end, the objectives of this study have been described.In the chapter two, we synthesized a TLCP via low-temperature solution polycondensation and prepared various concentrations of TLCP / MWNTs by in situ polymerization. Differential scanning calorimetry, thermogravimetric analyzer, X-ray diffraction and polarized optical microscopy were used to investigate the thermal behavior, crystalline structure and liquid crystalline properties of the pure TLCP and TLCP/MWNTs nanocomposites. Scanning electron microscopy images showed that a small quantity of MWNTs was well separated in the TLCP matrix. The X-ray diffraction results suggested that the addition of MWNTs to TLCP did not significantly change the crystal structure of TLCP. The thermogravimetric analyses indicated that a small quantity of MWNTs could improve the thermal stability of TLCP matrix.In the chapter three, we prepared lyotropic liquid crystal/carbon nanotube composites, and characterized them with FTIR, transmission electron microscopy and polarized optical microscopy. Polarized optical microscopy demonstrated that modified carbon nanotubes were dispersed well than nonnmodifed carbon nanotubes. Conductivity measurement suggested that carbon nanotubes were reoriented under external field, which demonstrated that the response time of lyotropic liquid crystal was quicker.Chapter 4 includes conclusion and prospects.