?The liquid crystallinity of the dimer of 4-benzoyloxybenzoic acid (BBA), with ex-cellent melt flow property was observed. The axial ratio (l/d) of (BBA), was calcu1ated tobe 5- 8 whlch is large en0ugh to exhlbit Iiquid crystalline phase. The nematic phase was sta-ble at 230 C. At higher temperature(270C ), the transesterification reaction occurred. Theeutectic temperature of BBA and 4-acetoxybenzoic acid is l75 C。
The polymerzation of tetrahydrofuran (THF) initiated by heteropolyacid—H\-3PW\-\{12\}O\-\{40\} in low concentration could be promoted by oxetane (OX), but the polymerization stopped at lower conversion than that promoted by oxiranes. The chain structure analysis by NMR spectra showed that OX was more reactive toward polymerization than oxiranes and more than 80% of OX were consumed through copolymerization, but not initiation. By stepwise addition of OX the conversion of THF polymerization could be increased higher than 50%. The percentage of the hydroxyl group attached to OX moieties at the polymer chain\|ends was higher than 50% of the total hydroxyl end\|groups, inferring that polymerization proceeded quite similar to that promoted by ethylene oxide and each chain was started with the OX moiety.
The polymerization of tetrahydrofuran(THF) initiated by heteropolyacid—H 3PW 12 O 40 (PW 12 ) in low concentrations could be effectively promoted by epichlorohydrin(ECH).However, the promotion activity of ECH is lower than that of EO or PO, especially when water was introduced. The polymerization started upon addition of epichlorohydrin.When the polymerization has stopped, it could be re\|initiated with the addition of a new portion of ECH. The products were found to be copolyether glycols with hydroxyl groups at both ends.The percentage of the hydroxyl group attached to ECH moieties at the polymer chain\|ends was higher than 50% of the total hydroxyl end\|groups. Most of the ECH moieties in chains attached to hydroxyl end groups, and no primary hydroxyl groups derived from ECH could be detected.
The liquid crystalline copolyester (LCP)/montmorillonite nanocomposites were prepared by polycondensation of terephthalic acid, p \|acetoxy benzoic acid and 1,2\|diacetoxy benzene,in the presence of an organically modified montmorillonite(OMt) with p \|aminobenzoic acid hydrochloride.The cleavage effect of OMt and the liquid\|crystalline behavior of the composites were described.\;The cleavage effect of OMt was examined by X\|ray diffraction (XRD) and transmission electron microscopy (TEM).Room\|temperature XRD spectra were collected from 2θ=2° to 2θ=10°. The eventual disappearance of any distinct X\|ray diffraction peaks for the hybrid containing 2,3,or 5wt% OMt indicated the well dispersion of its original layer structure.The TEM micrograph showed that the silicate layer spacings were greater than 3nm,even some layers dispersed in polymer matrix individually.\;The glass transition temperature T \-g of the LCP/OMt nanocomposites increased slightly as compared with the pure polymer,but the isotropic temperatues T i decreased more significantly as the content of OMt increased.As the clay content increased up to 3%,the decrease of T i reached 25℃.LCP chains separated in certain degree by inorganic phase decreased the ordering ability of mesogenic units.This may be the principal reason for the descent of T i.\;The nematic texture of nanocomposites was observed by POM,and the schlieren texture became indistinct as the clay content increased.Although the schlieren texture in POM for the hybrid with clay content up to 5% still could be observed,the evident location of disinclination point already cant be found.Thus,the mechanism of disinclination in nematic phase for LCP hybrid with OMt is more complicated than that for pure polymer.
