Showing papers on "Polytetrahydrofuran published in 1987"

Narrowing the molecular weight distribution of poly-tetrahydrofuran and of copolymers of tetrahydrofuran and alkylene oxides

Abstract: The molecular weight distribution of polytetrahydrofuran and of copolymers of tetrahydrofuran and alkylene oxides is narrowed by a process in which the polymers are mixed with a solvent mixture consisting of (a) an alkanol, (b) a hydrocarbon and (c) water, the content of the individual components a, b and c in the mixture being from 8 to 60% by weight, after which the three phases formed are separated from one another and the polymer having the narrower molecular weight distribution is isolated from the two lower phases.

Process for the limitation of the molecular weight distribution of polytetrahydrofuran and of copolymerisates of tetrahydrofuran and alkylene oxides

Abstract: Verfahren zur Einengung der Molekulargewichtsverteilung von Polytetrahydrofuran und von Copolymerisaten aus Tetrahydrofuran und Alkylenoxiden, wobei man die Polymerisate mit einem Losungsmittelgemisch aus (a) einem Alkanol, (b) einem Kohlenwasserstoff und (c) Wasser, wobei der Gehalt der Einzelkomponenten a, b und c im Gemisch zwischen den Grenzen 8 bis 60 Gew.% liegt, vermischt, danach die drei sich bildenden Phasen voneinander trennt, und das Polymerisat mit engerer Molekulargewichtsverteilung aus den beiden unteren Phasen isoliert. A process for narrowing the molecular weight distribution of polytetrahydrofuran and copolymers of tetrahydrofuran and alkylene oxides to give the polymers with a solvent mixture of (a) an alkanol, (b) a hydrocarbon and (c) water, wherein the content of the individual components a, b and c by weight in the mixture between the boundaries 8 to 60.% is mixed, after which the three phases forming separates, and the polymer having a narrower molecular weight distribution from the two lower phases isolated.

Living Polymerization of Isobutylene

Abstract: Truly living polymerizations, i.e., polymerizations that proceed in the absence of termination and chain transfer, are a most desirable objective of the synthetic polymer chemist. Living polymerizations are not only of great scientific interest but also of considerable commercial consequence and several modern industrial processes are based on living systems, e.g., cis-1,4-polybutadiene,1 triblock polymers of styrene/butadiene/styrene,2 polytetrahydrofuran;3 however these processes are not carbocationic in nature.

Synthesis of carboxyl terminated vinyl liquid polymers

Abstract: This invention provides a method for copolymerizing saturated hydroxyl-terminated liquid polyethers and the reaction of this copolymerized ether with dibasic anhydride in presence of various acids or alkalis as catalysts. When the reaction temperature is raised to 100-180 deg.C, and after 2-10 hrs., conversion of terminal groups reaches 100%. The said hydroxyl-terminated polyethers refer mainly to hydroxyterminated polytetrahydrofuran, liquid copolymerized ethers of hydroxyterminated tetrahydrofuran-propylene oxide, hydroxyterminated tetrabydrafuran-propylent oxide, hydroxyterminated propylene oxide liquid polyethers, especially the hydroxyterminated epichlorohydrin liquid polyethes. The diacidic anhydride mainly refers to maleic anhydride.

Synthesis and characterization of high performance polytetrahydrofuran based polyurethane-urea and ionene elastomers

Abstract: ii produce good physical properties. Photochromic as well as thermochromic phenomena were also noticed in these systems.

Resin composition having high specific gravity

Abstract: PURPOSE:To provide a resin compsn. having a high specific gravity and excellent moldability, impact resistance, etc., by mixing a copolymer comprising a high-molecular component composed of a 10C or higher omega-aminocarboxylic acid, etc., and a polytetrahydrofuran component as essential components with metallic powder. CONSTITUTION:A high-molecular component (A) composed of a 10C or higher aminocarboxylic acid or lactam (e.g., a omega-aminoundecanoic acid polymer, a laurolactam polymer) is bonded to a polytetrahydrofuran component (B) by using a dicarboxylic acid (C) (e.g., terephthalic acid) to produce a copolymer. 5-50wt% copolymer is mixed with 95-50wt% metallic powder (e.g., iron powder) to obtain the desired resin compsn. having a high specific gravity. In this way, the resin compsn. contg. metallic powder uniformly dispersed therein can be obtd. and moldings of uniform quality can be easily obtd. therefrom. The resin compsn. is suitable for use in the production of a flywheel, etc.