摘要:
A novel reverse osmosis membrane comprising a hydroxyalkyl methacrylate film cross-linked with a vinylaralkyl dialkylsulfonium salt is described. This film, when cast on a compatible substrate, results in a membrane of exceptional chlorine resistance.
摘要:
Water-soluble sulfonium salts are converted, without the elimination of odorous volatile by-products, to water-insoluble products useful as binders in coating formulations by heating a water-soluble cyclic sulfonium salt in which the sulfonium sulfur is bonded only to aliphatic carbons.
摘要:
Microporous, asymmetric membranes comprising syndiotactic vinylaromatic polymers having utility as membranes for ultrafiltration or reverse osmosis and a process for their production.
摘要:
Reverse osmosis membranes treated with polymers bearing carboxylic acid groups and optionally pendant hydroxyl or amide moieties display enhanced salt rejection and/or increased water flux. This treatment is particularly useful for improving the membrane characteristics of cellulose acetate and polyamide membranes.
摘要:
An improved composite polyamide membrane and methods of making the membrane are described. This improved membrane is prepared using a cationic polymeric wetting agent in an aqueous solution containing a polyfunctional amine reactant which is interfacially polymerized with an acyl halide to form a thin film polyamide discriminating layer on a microporous support. Alternatively, the wetting agent can be applied directly to the substrate and the interfacial polymerization can occur on said treated substrate. The resulting membrane exhibits an unexpected combination of high water flux, high rejection of divalent anion salts, variable sodium chloride rejection and good caustic resistance at low operating pressures. In one embodiment of this invention, a porous substrate is first treated with an aqueous piperazine solution containing a copolymer of vinylbenzyl dimethyl sulfonium chloride and methacrylic acid and then the coated microporous support is contacted with trimesoyl chloride in an organic solvent.
摘要:
Structured particle latexes contain organic polymer particles in aqueous media having a nonionic core encapsulated by a thin layer of a water-insoluble copolymer containing pH independent stabilizing anionic groups such as sulfonate groups chemically bound at or near the particle surface.
摘要:
Substantially linear, synthetic, water-soluble or water-dispersible cationic interpolymeric surfactants which are particularly useful for reducing the surface tension of an aqueous medium; such surfactants having a critical micelle concentration of from 0.01 to about 10 percent in water at 25.degree. C., a charge density of from about 1 to 5 meq/g and a number average molecular weight of from about 500 to about 40,000 and being composed of a plurality of nonionic hydrophobic units and pH independent hydrophilic cationic units randomly distributed in the backbone of such interpolymeric surfactants and wherein an average molecule of such surfactant contains from 1 to about 5 hydrophilic cationic units substituted with a pendant hydrophobic group, such hydrophobic group being an alkyl or aralkyl group of from about 8 to about 20 carbon atoms are prepared by (1) aqueous, emulsion polymerization of a mixture of ethylenically unsaturated nonionic monomers at least one of which contains an ion-forming group in the presence of a copolymerizable monomeric surfactant to form a latex, (2) reacting the resulting latex with a coreactant to form a water-soluble cationic interpolymer.
摘要:
A fibrous product containing (a) a papermaking grade of pulp, (b) a structured particle latex having pH independent cationic groups bound at or near the particle surface and (c) a co-additive. The pulp is represented by unbleached softwood kraft. The latex is represented by a structured-particle latex having (a) a core of a copolymer of styrene and butadiene (b) an encapsulating layer of styrene, butadiene and vinylbenzyl chloride which is reacted with 2-(dimethylamino) ethanol to form quaternary ammonium groups. The co-additive is represented by a hydrolyzed polyacrylamide having a degree of polymerization of 5500. To an aqueous slurry of the pulp are added the latex and an aqueous solution of the co-additive, the resulting suspension is dewatered and dried by heating.
摘要:
An improvement in the process of forming plastic articles wherein such articles are forged from a compression formed briquette of resinous powder, such improvement comprising (1) compressing a resinous powder having lamellar crystalline nonspherulitic morphology into a substantially unoriented briquette having green strength, (2) removing the briquette from the compressing device and placing the briquette in a forging press wherein lubrication is provided between the contacting surfaces of the briquette and the forging press to permit plug flow, and (3) forging the briquette into a shaped article while maintaining the briquette at a temperature between the alpha-transition temperature and the melt temperature of the resinous powder.
摘要:
Structured-particle latexes are prepared from nonionic or slightly cationic latexes, either preformed or polymerized in situ, by emulsion polymerizing monomeric materials which include an ethylenically unsaturated, activated-halogen monomer such as vinylbenzyl chloride in the absence of a sufficient amount of a surfactant to initiate new particles whereby the activated-halogen monomer is copolymerized on the surface of the existing particles which are dispersed in aqueous media. To the resulting structured particle latex may then be added conventional cationic surfactants to provide greater stability. The cationic latexes are suitable for coatings.