Abstract: The invention relates to a process for preparing high temperature-resistant dense or cellular polyurethane elastomers by reacting the following, preferably using low-pressure processing techniques:(a) organic polyisocyanates, preferably in the form of isocyanate group-containing prepolymers and/or modified urethane group-containing organic polyisocyanates, with(b) relatively high molecular weight compounds having at least 2 reactive hydrogen atoms,(c) urea derivatives and, optionally,(d) chain extenders and/or cross-linking agents in the presence of(e) catalysts and, optionally,(f) blowing agents(g) auxiliaries and/or additiveswherein amino and/or hydroxyl group-substituted ureas and/or polyureas having molecular weights from 200 to 4000 are also used as the urea derivatives. Said ureas and/or polyureas are prepared by reacting organic diisocyanates with primary aliphatic and/or cycloaliphatic diamines and/or alkanolamines in molar ratios of from 1:1.

Abstract: The invention relates to a process for the preparation of cellular or noncellular plastics, preferably polyurethane coatings, by reacting at least two components with one another, preferably organic polyisocyanates and polyhydroxyl compounds, by feeding the components into a mixing zone separately, and mixing them together and then discharging the reaction mixture from the mixing zone, while adding air heated to a temperature of 100.degree. to 1200.degree. C. to the reaction mixture as it emerges from the mixing zone.

Abstract: This invention relates to a process for improving the ultraviolet light transmittance of ethylene glycol by treating industrial grade ethylene glycol with an aluminum-nickel alloy in the presence of an alkali compound.

Abstract: The invention relates to urea group-containing polyisocyanate mixtures which are liquid at room temperature and have an isocyanate group content of from 15 to 30 weight percent and a diphenylmethane diisocyanate content of from 55 to 90 weight percent, obtained through the reaction of(A) polyoxyalkylene polyamines having a functionality of from 2 to 5 and an amine number from 20 to 250 with a polyisocyanate (B) selected from the group consisting of(B1) a mixture of diphenylmethane diisocyanates and polyphenyl polymethylene polyisocyanates having a diphenylmethane diisocyanate content of from 55 to 90 weight percent or(B2) at least one diphenylmethane diisocyanate isomer.The polyisocyanate mixtures claimed in the invention are used to prepare dense or cellular polyurethane and/or polyisocyanurate plastics, in particular, flexible polyurethane foams.

Abstract: Reinforced cellular or noncellular molded polyurethane parts are prepared by heating a mixture of reinforcing materials and a heat-curable composition of polyisocyanates and polyols in an open or closed mold, said composition being storage-stable at room temperature and containing, optionally, auxiliaries and additives. In said composition, the polyisocyanate is dispersed in the form of discreet particles having particle diameters from 0.1 to 150 .mu.m in the polyol and the polyisocyanate particles are deactivated on their surfaces such that from 0.01 to 20 equivalent percent of the total available isocyanate groups are deactivated and such that the ratio of free isocyanate groups to hydroxyl groups is from 0.7:1 to 2.5:1.The polyurethane molded parts are suitable for use as self-supporting trim parts, reinforcement parts, or molded parts for various applications.

Abstract: The present invention is directed to the fabrication of ceramic composites which possess improved mechanical properties especially increased fracture toughness. In the formation of these ceramic composites, the single crystal SiC whiskers are mixed with fine ceramic powders of a ceramic material such as Al.sub.2 O.sub.3, mullite, or B.sub.4 C. The mixtures which contain a homogeneous disperson of the SiC whiskers are hot pressed at pressures in a range of about 28 to 70 MPa and temperatures in the range of about 1600.degree. to 1950.degree. C. with pressing times varying from about 0.75 to 2.5 hours. The resulting ceramic composites show an increase in fracture toughness of up to about 9 MP.am.sup.1/2 which represents as much as a two-fold increase over that of the matrix material.