Abstract: The purpose of the present invention is to provide a polyimide resin which exhibits higher heat resistance than that of a conventional polyimide resin by controlling the geometric configuration of the constituent units. Provided is a polyamic acid which comprises repeating units represented by general formula (1), wherein the 1,4-bismethylenecyclohexane skeleton units consist of both trans- and cis-form units, and the contents of the trans- and cis-form units are 60 to 100% and 0 to 40% respectively (with the sum total of the trans- and cis-form units being 100%).

Abstract: A polyamic acid solution includes a polyamic acid, a solvent (C) in which the polyamic acid (PAA1) is dissolved, and a substance (M) that can release at least one metal selected from groups 1 and 2 of the periodic table as a metal ion, or a substance (m) that contains the substance (M). A polyimide composite is produced from the polyamic acid solution. The polyimide composite can provide a greatly improved glass transition temperature without impairing the intrinsic physical properties of the polyimide.

Abstract: The invention provides a piezoelectric polymer material including a helical chiral polymer having a weight average molecular weight of from 50,000 to 1,000,000 and having optical activity, the piezoelectric polymer material having a piezoelectric constant d14 at 25° C. of 10 pC/N or more, a degree of crystallinity obtained by X-ray diffraction of from 40% to 80%, and a haze of from 0.5 to 30.

Abstract: The invention provides a piezoelectric polymer material including a helical chiral polymer having a weight average molecular weight of from 50,000 to 1,000,000 and having optical activity, the piezoelectric polymer material having a piezoelectric constant d14 at 25° C. of 10 pC/N or more, a degree of crystallinity obtained by X-ray diffraction of from 40% to 80%, and a haze of from 0.5 to 30.

Abstract: The purpose of the present invention is to provide a polyimide resin which exhibits higher heat resistance than that of a conventional polyimide resin by controlling the geometric configuration of the constituent units. Provided is a polyamic acid which comprises repeating units represented by general formula (1), wherein the 1,4-bismethylenecyclohexane skeleton units consist of both trans- and cis-form units, and the contents of the trans- and cis-form units are 60 to 100% and 0 to 40% respectively (with the sum total of the trans- and cis-form units being 100%).

Abstract: A polyamic acid solution according to the present invention includes a polyamic acid, a solvent (C) in which the polyamic acid (PAA1) is dissolved, and a substance (M) that can release at least one metal selected from groups 1 and 2 of the periodic table as a metal ion, or a substance (m) that contains the substance (M). A polyimide composite according to the present invention is produced from the polyamic acid solution. The present invention provides a polyimide composite having a greatly improved glass transition temperature without impairing the intrinsic physical properties of the polyimide.

Abstract: The present invention provides a syndiotactic polypropylene resin composition of excellent moldability comprising 100 parts by weight of a syndiotactic polypropylene and 0.001-10 parts by weight of a diamine/monocarboxylic acid condensate and/or a diamine/monocarboxylic acid/polybasic acid polycondensate. The composition has excellent moldability, particularly, excellent releasability from mold in injection molding; excellent transparency; and good balanced mechanical properties.

Abstract: Disclosed herein is a method for controlling the molecular weight of a propylene homo- or co-polymer at a constant level upon subjecting propylene alone or a mixture of propylene and another .alpha.-olefin copolymerizable with propylene as a monomer or monomer mixture to bulk polymerization in the presence of hydrogen as a molecular weight modifier in a reaction tank equipped with a reflux condenser.

Abstract: A block copolymer of propylene can be obtained with its quality controlled uniform by conducting at first continuous polymerization of propylene in a polymerization system, receiving a polymer slurry, which has been discharged continuously from the polymerization system, in a batchwise polymerization tank, feeding ethylene to the tank to conduct batchwise polymerization of ethylene and propylene. Upon discharge of a copolymer slurry formed by the preceding batchwise polymerization, at least a predetermined amount of unreacted ethylene is left over in the tank. Into the tank with the unreacted ethylene still left over therein, there are simultaneously charged the polymer slurry from the polymerization system and a deactivator. During this charging, ethylene is not supplied.

Abstract: A block copolymer of propylene is produced by using propylene itself as a liquid medium, conducting continuous polymerization (former-stage polymerization) of propylene alone or propylene and a small amount of ethylene at first and then conducting batchwise copolymerization (latter-stage polymerization) of ethylene and propylene. The amount of an activity improver to be added to a polymerization tank for the latter-stage polymerization and/or the polymerization time of the latter-stage polymerization are controlled in accordance with the amount of a slurry transferred from a polymerization tank for the former-stage polymerization to the polymerization tank for the latter-stage polymerization so as to maintain the ratio of the amount of the polymer polymerized by the former-stage polymerization to the amount of the polymer polymerized by the latter-stage polymerization constant in the block copolymer.

Abstract: A propylene-ethylene block copolymer is produced by continuous bulk polymerization in which propylene alone is polymerized or propylene and ethylene are copolymerized at the ethylene/propylene reaction ratio of 6/94 using propylene as a liquid medium, and subsequently by batch-wise copolymerization in which propylene and ethylene are copolymerized at the ethylene/propylene reaction ratio from 85/15 to 5/95.

Abstract: Method of adding water and a hydroxide of an alkali metal or alkaline earth metal to a washing solvent such as an alkylamide and/or alkylsulfoxide when washing and removing high molecular substances stuck on the interior of a production apparatus or molding machine for an aromatic vinyl-acrylonitrile copolymer. A method for regenerating and recovering the washing solvent used for the above-mentioned washing and removal by means of an evaporator and distillation tower.