Synthesis and eutectic behavior of liquid crystalline copolyesters

Abstract

A series of liquid crystalline copolyesters, derived from 1,4‐hydroxy‐benzoic acid (HBA), 6‐hydroxy‐2‐naphthoic acid (HNA), terephthalic acid (TA), and hydroquinone (HQ), were prepared; crystallization, melting and solid‐state structure of the copolyesters were studied by using differential scanning calorimetry (DSC) and wide‐angle x‐ray diffraction (WAXD). It was found that the variation of melting point of the copolyesters with increasing HBA mol % exhibits eutectic melting behavior at a constant mole ratio of HNA, and the extrapolated eutectic temperature decreases linearly with increasing HNA mol %. WAXD analysis of the copolyesters indicates that the d‐spacing related to three‐dimensional order increases first and then decreases with increasing HBA mol %. The increase of the d‐spacing, consistent with looser packing of chains, leads to the reduction of melting point and most likely accounts for the eutectic behavior observed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2171–2177, 2009

Dependence of the Physical Properties and Molecular Dynamics of Thermotropic Liquid Crystalline Copolyesters on p-Hydroxybenzoic Acid Content

“…These values then gradually increased as the HBA molar ratio increased up to 5. The shape of the eutectic curve, which depends on the amount of HBA monomer content in the TLCP copolymer, has been described in detail previously, and similar results have been published by several researchers [11,19,32,33]. The temperature change of our study according to the HBA molar ratio is small compared to other research results, which is probably due to the alkoxy side groups in the main chain.…”

Annealing effect of thermotropic liquid crystalline copolyester fibers on thermo- mechanical properties and morphology

“…Figure 1 shows the effect of the HBA monomer concentration on the overall thermal properties (T g , T m , T i , and T D i ) of Co-TLCP. T g and T D i showed the lowest values at 3 mol HBA, and the polymer exhibited eutectic behavior, in which the thermal properties improved when the HBA content was decreased or increased past 3 mol HBA, i.e., 3 mol HBA was the eutectic point [25][26][27] (see Supplementary Information S2).…”

Influence of hydroquinone content on thermotropic liquid crystalline copolymers and nanocomposites: thermo-mechanical properties and morphology

“…The structure of the synthesized Co-TLCP was conrmed using Fourier-transform infrared (FT-IR) spectroscopy (Bruker VERTEX 80v, Berlin, Germany) and carbon-13 nuclear magnetic resonance ( 13 C-NMR) spectroscopy (Bruker 400 DSX NMR, Berlin, Germany). 13 C cross-polarization (CP)/magic angle spinning (MAS) NMR experiments were performed at a Larmor frequency of 100.61 MHz, and an MAS rate of 12 kHz to minimize the rotating sidebands. Tetramethylsilane (TMS) was used to standardize the NMR spectra.…”

“…Solid 13 C CP/MAS at room temperature was used for a more accurate Co-TLCP structure analysis. 30 The 13 C chemical shi of the Co-TLCP prepared with a 1 : 4 ¼ ETA : HQ molar ratio was obtained for the carbons of the alkoxy groups and aromatic rings.…”

“…11,12 By the introduction of a exible alkyl group into the rigid main chain, the melting point can be lowered, the solubility of the polymer can be increased, and the compatibility between the matrix polymer and the additive can be increased when used as a composite material. [13][14][15] Therefore, despite the slightly inferior physicochemical properties, improvements in the applicability in several areas may be achieved by increasing the compatibility by using the intermolecular attraction of the chain by employing the alkyl group. Fillers such as elastomers, clays, or glass bers have long been added as reinforcing bers for improving the physical properties of TLCP.…”