Abstract: A method for producing a liquid crystalline polyester, which comprises reacting compounds of the following formulas: ##STR1## and a dicarboxylic acid of the following formula ##STR2## wherein R.sup.1 is a bivalent aromatic hydrocarbon group having from 6 to 18 C atoms as starting material, for polycondensation in a molten state.

Abstract: A liquid crystalline polyester comprising dicarboxylic acid units of the following formula (1): ##STR1## wherein R.sup.1 is a bivalent aromatic hydrocarbon group having from 6 to 18 carbon atoms, diol units of the following formula (2):--OCH.sub.2 CH.sub.

Abstract: A hollow article or sheet of a copolyester which comprises, as main components, terephthalic acid as a dicarboxylic acid component and ethylene glycol as a diol component and which is characterized by:(1) isophthalic acid as a dicarboxylic acid component being from 0.5 to 3.0 mol %,(2) diethylene glycol as a diol component being from 1.0 to 2.5 mol %,(3) the intrinsic viscosity being from 0.60 to 1.50 dl/g,(4) the concentration of terminal carboxyl groups being at most 18 eq/ton, and(5) the content of a cyclic trimer being at most 0.40% by weight.

Abstract: A copolyester which comprises, as main components, terephthalic acid as a dicarboxylic acid component and ethylene glycol as a diol component and which is characterized by:(1) isophthalic acid as a dicarboxylic acid component being from 0.5 to 3.0 mol %,(2) diethylene glycol as a diol component being from 1.0 to 2.5 mol %,(3) the intrinsic viscosity being from 0.60 to 1.50 dl/g,(4) the concentration of terminal carboxyl groups being at most 18 eq/ton, and(5) the content of a cyclic trimer being at most 0.40% by weight.

Abstract: The aromatic polyester and aromatic polyester-amide of the present invention have an excellent heat resistance (soldering resistance) and are excellent in fluidity, and therefore, excellent in moldability, because they show liquid crystallinity in a molten state. In view of mechanical characteristics, the aromatic polyester and aromatic polyester-amide of the present invention have a high modulus of elasticity and are excellent in mechanical strength. In addition, the aromatic polyester and aromatic polyester-amide of the present invention have an advantage that they can be molded at a temperature of 350.degree. C. or below, especially, 320.degree. C. or below.The aromatic polyester and aromatic polyester-amide of the present invention have utility in injection molded articles, films, fibers, etc., due to the above properties thereof.In addition, the aromatic polyester and aromatic polyester-amide of the present invention become molten state at a temperature of 320.degree. C.

Abstract: A wholly aromatic polyester consisting essentially of:(a) from 2 to 50 equivalent % of a 3,3'-biphenyldicarboxylic acid residue;(b) from 10 to 40 equivalent % of a dicarboxylic acid residue excluding the residue of 3,3'-bisphenyldicarboxylic acid;(c) from 10 to 52 equivalent % of a dioxy compound residue of the formula: ##STR1## wherein R.sup.2 is a group of the formula ##STR2## wherein R.sup.6 is a C.sub.1 -C.sub.4 alkyl group or a phenyl group and n is 0 or an integer up to 4, ##STR3## wherein X is as defined above, ##STR4## wherein X is as defined above, and/or ##STR5## and (d) from 0 to 80 equivalent % of an oxycarboxylic acid residue of the formula: ##STR6## wherein R.sup.3 is a bivalent aromatic hydrocarbon group or R.sup.4 --X--R.sup.5, wherein R.sup.4, R.sup.5 and X are as defined above, said polyester having a melt viscosity of at least 50 poise as measured at 275.degree. C. at 100 sec.sup.-1.

Abstract: A process for producing a copolymeric polyester, which comprises a first step of preparing a copolymeric oligomer by reacting a starting material oligoester or polyester having repeating units of the formula: ##STR1## wherein R.sub.1 is a divalent aromatic hydrocarbon group having from 6 to 10 carbon atoms, a divalent alicyclic hydrocarbon group having from 4 to 20 carbon atoms or/and a divalent aliphatic hydrocarbon group having from 1 to 40 carbon atoms (provided a hydrogen atom in the aromatic ring of the aromatic hydrocarbon group may be substituted by a halogen atom or an alkyl or alkoxy group having from 1 to 4 carbon atoms), and R.sup.

Abstract: A selective gas separator composed essentially of a reaction product of copper compound with an imidazole, a pyrazole, a triazole and/or a tetrazole.

Abstract: A polyolefin is producing by polymerizing ethylene or copolymerizing ethylene and the other .alpha.-olefin at 50.degree. to 100.degree. C. in a hydrocarbon solvent in the presence of a catalyst system of an organoaluminum compound and a transition metal compound component which is a solid catalytic component containing a magnesium compound and a titanium compound under the condition (a) two step polymerizations of a first polymerization step and a second polymerization step in the presence of a reaction mixture obtained by said first polymerization step; (b) a polymerization in the presence of hydrogen at a molar ratio of H.sub.2 to C.sub.2 H.sub.4 (vapor phase) of 0.01-0.8 to produce a polymer A having a viscosity average molecular weight of 2.times.10.sup.5 -7.times.10.sup.5 at a ratio of 30 to 70 wt. % based on the total polymer in one of said first or second polymerization step and a polymerization in the presence of hydrogen at a molar ratio of H.sub.2 to C.sub.2 H.sub.4 (vapor phase) of 1.