Blends of thermotropic polyester with poly(phenylene oxide)

Abstract

SYNOPSISA thermotropic liquid crystalline polymer ( LCP) based on wholly aromatic copolyesters based on hydroxynaphthoic and hydroxybenzoic acid was melt-blended with a thermoplastic poly (phenylene oxide) by corotating twin screw extruder. Rheological properties, temperature transitions, dynamic and mechanical properties, and electron microscopy study have been performed. Rheological study indicated significant viscosity reductions with increasing LCP content leading to ease of processing. From the differential scanning calorimeter ( DSC ) and dynamic mechanical thermal analyzer results, these blends showed incompatibility for the whole range of concentrations. Mechanical properties were found to be slightly improved a t low LCP and dramatically improved a t above 50% LCP contents. In addition, impact strength was significantly increased up to two times after adding 10% LCP into the matrix. The morphology of blends was affected by composition. Droplets and stubby fibrils structures caused lower tensile strength, whereas fibrillar structure improved this property.

Characterization of thermotropic liquid crystalline polyester/polysulfone blends

“…The increase in impact strength at low LCP concentration may be due to the small domain size, which can bring about branching of the propagating crack. Similar trends in tensile and impact strengths were also seen by Limtasiri and Isayev in LCP/PPO blends (20).…”

“…It appears from the literature that the influence of LCP on the mechanical properties of injection molded blends depends on the polymers used, the processing conditions, and LCP concentration (2,(8)(9)(10)(11)(12)(13)(14)(20)(21)(22)(23)(24)(25)(26). The addition of LCP to a polymer may increase (12, 15).…”

Rheological behavior comparison between PET/HDPE and PC/HDPE microfibrillar blends

“…It is well known that fibrillar morphology can greatly improve the mechanical properties of the fiber/polymer composite when the mechanical properties of the fibers are superior to the polymer matrix, and the interfacing interaction between the fibers and the matrix is strong enough. Therefore, some measures have been taken to make the dispersed phase (typically of a liquid crystalline polymer [7,8] or a thermoplastic plastic) deform in situ into fibers. In previous works [9,10] we used a two-step strategy to prepare the in situ microfibrillar blending materials based on the concept that two immiscible thermoplastic plastics have distinctly different processing temperatures.…”

Compatibilizing effect of styrene-maleic anhydride copolymer on the properties of polyamide-6/liquid crystalline copolyester composites

“…[1][2][3][4][5][6][7][8] This is because LCPs can be deformed into fine and elongated fibrils within an isotropic matrix under appropriate processing conditions, leading to so-called in situ polymer composites. However, immiscibility and poor interfacial adhesion between the LCP dispersed phase and the thermoplastic matrix generally result in the LCP/thermoplastic blends having low tensile strength and impact toughness, so the development of in situ composites is restricted.…”