Abstract:
A continuous process for preparing polybenzazole staple fibers which comprises supplying polybenzazole polymer through an extruder (1) to a spinning head (2) for spinning, passing the filaments through a quench chamber (3), around rollers (4) and through a cutting device (5) which cuts the filaments into staple fibers.
Abstract:
A process for preparing a polymer or copolymer from polymerizable monomers by suspension polymerization whereby foam formation during the removal of residual monomers is inhibited, which process comprises adding at least one salt of an inorganic acid having an anionic valency of at least 2 to the polymer slurry prior to the removal of the residual monomer.
Abstract:
Vinylidene chloride polymer compositions comprising a vinylidene chloride polymer and from 2 to 12 weight percent of a glycerin ester provide films which exhibit oxygen transmission rates sufficiently low to protect gassy cheeses from spoilage but sufficiently high to let any excess CO2 produced during the cheese curing process escape from the packaged gassy cheeses.
Abstract:
A process of preparing diaryl carbonates, such as diphenyl carbonate, and aryl haloformates, such as phenyl chloroformate. The process involves contacting phenol or a substituted phenol with a carbonyl halide, such as phosgene, in the presence of a phosphorus- containing catalyst. The catalyst is selected from alkyl phosphates, aryl phosphites, aryl phosphates, organic phosphinites and phophinates, organic pyrophosphates, inorganic phosphorous and phosphoric acids, and phosphorus oxides.
Abstract:
An improved polymer devolatilization apparatus comprising a flat plate heater (22) comprising a polymer solution supply means (20), and a liquid/vapor collection and separation means, said flat plate heater further comprising a multiplicity of flat plates defining a plurality of channels (10), each channel having a substantially uniform height, but varying width over the total channel length, each channel comprising three zones: a first zone (12), having a beginning (18) and a terminus, said beginning in operative communication with the polymer solution supply means, characterized by decreasing width as a function of distance from its beginning, a second zone (14) having a beginning at the terminus of the first zone and a terminus, characterized by at least one occurrence of a restrictive cross-sectional area, and a third zone (16) having a beginning at the terminus of the second zone and terminating at a liquid/vapor collection and separation region operating at reduced pressure, said third zone characterized by increasing width as a function of distance from its beginning, and provided further that the ratio of maximum width of the third zone to the maximum width of the second zone is from 2:1 to 20:1.
Abstract:
Rubber-modified monovinylidene aromatic copolymers having an enhanced combination of gloss, toughness and melt flow characteristics are provided by a process wherein a rubber latex having a specified particle size is partially agglomerated, emulsion graft polymerized to a specified graft copolymer to rubber (G:R) ratio and a specified graft copolymer molecular weight and further agglomerated during subsequent dewatering and/or melt-compounding operations.
Abstract:
A method of making metallic carbide powders includes heating a non-static solid reactant mixture of a metal oxide and a source of carbon to a first elevated temperature which is sufficient to cause at least partial carburization of the mixture. The heating is performed in a non-reducing atmosphere having a total pressure of at least one atmosphere for a sufficient time to form a partially-carburized mixture. The source of carbon is employed at a level which is less than the stoichiometric amount needed to produce the metallic carbide. The method may further include admixing a sufficient level of a source of carbon to the partially-carburized mixture to form an adjusted mixture having a total carbon content of the stoichiometric amount needed to make the metallic carbide and carburizing the adjusted mixture in a hydrogen-containing atmosphere at a second elevated temperature which is sufficient to cause the adjusted mixture to form the metallic carbide having a particle size of less than 0.2 micrometers in diameter.
Abstract:
The oligomers of the present invention are polythioureas having 3 to 50 recurring units derived from aromatic diamines substituted with anionic groups, and having a number average molecular weight of less than 10,000. These oligomers are water-soluble, preferably have a rigid backbone, and are pharmaceutically acceptable. The oligomers are useful for the treatment and/or diagnosis of AIDS.
Abstract:
A reaction between: (1) a compound that contains one or more epoxide moieties per molecule, and (2) a compound that contains one or more primary aliphatic hydroxyl groups per molecule; is catalyzed by: (3) trifluoromethanesulfonic acid or a derivative therof and run at a temperature of no more than 130 DEG C. The catalyst preferably catalyzes reaction at the primary aliphatic hydroxyl group, so that the resulting resin does not gel. It can be optionally used at relatively moderate temperatures without solvents.