Rheological, Dynamic Mechanical and Thermal Properties of Thermotropic Liquid Crystalline Polymer/Unsaturated Polyester/Glass Fiber Hybrid Composites

Abstract

Unsaturated polyester (UP) reinforced with self-synthesized reactive thermotropic liquid crystalline polymer (TLCP)-methacryloyl copolymer (LCMC) and glass fiber (GF), the hybrid composites of UP/GF/LCMC are prepared by molding technology. The dynamic mechanical analysis (DMA) indicate that storage modulus and glass transition temperature (T g ) of hybrid composites increase significantly because of the addition of LCMC. The thermal expansion coefficient of composites containing 5% LCMC decrease by about 30% than that of composites without LCMC. Rheological performance analysis show that the composites under melting stage are non-Newton liquid of shear thinning, and the processability of composites with 5% LCMC can be improved effectively. The crystal behavior analysis of LCMC/UP blend is investigated by X-ray diffraction (XRD) and polarizing optical microscope (POM). The results show that the crystal phase and texture structure of LCMC still exist in the blends after blending with UP.

Functionalization of Multiwalled Carbon Nanotubes with Thermotropic Liquid-Crystalline Polymer and Thermal Properties of Composites

“…To meet the rising demands of applications, hybrids of CNTs and high-performance polymeric materials are being continuously developed to combine their constituents’ beneficial properties or to induce new ones. Main-chain thermotropic liquid-crystalline polymers (TLCPs), which are a well-known class of high-performance polymers, offer a unique combination of desirable properties such as outstanding mechanical properties, thermal endurance, chemical resistance, good dimensional stability, and low coefficient of thermal expansion , and have been used extensively as resins for high-modulus fibers, coatings, and molded articles. − Fusing the two components into one molecular system, that is, attaching thermotropic liquid-crystalline polymers to the surface of CNTs, is particularly intriguing because the resulting material might be both liquid-crystalline and nanocharacteristic, which could offer an array of exciting opportunities for high-tech innovations. To reach more practical conditions for industrial processing, controlling mesophase transition temperatures and broadening mesophase temperature ranges of liquid-crystalline materials to improve the processability have always been important issues, , and several researchers have devoted considerable efforts to modify the structures and properties of liquid-crystalline polymers. − One research interest in our group is to create new easily processable and ultra-high-strength TLCP/CNT materials with combined advantages of the two components and with the mesophase temperature range of the TLCP enlarged in the presence of CNTs.…”