摘要:
A process for reducing the residual monomer content of a copolymer prepared by copolymerizing vinyl esters and N-vinyl-lactams in a solvent in the presence of a free radical polymerization initiator. Following the main polymerization, from 0.05 to 0.5% by weight, based on the monomers employed, of di-tert.-butyl peroxide, di-tert.-amyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-bis-(tert.-butylperoxy)-hexane, 2,2-bis-(tert.-butylperoxy)-butane, 1,1-bis-(tert.-butylperoxy)-3,3,5-trimethylcyclohexane, 4,4-di-(tert.-butylperoxy)-butyl valerate, or a mixture of these, is added to the reaction mixture and the after-polymerization is carried out at a higher temperature than the main polymerization.
摘要:
High molecular weight products based on N-vinylpyrrolidone, in which blocks of vinylpyrrolidone polymers or vinylpyrrolidone copolymers are linked by connecting units carrying ester, amide, urethane or urea groups, as a result of which these high molecular weight products are biodegradable and may be used as plasma substitutes, and the plasma substitutes thus obtained.
摘要:
A process for the preparation of modified poly-N-vinylpyrrolid-2-one containing two identical reactive groups, wherein polyvinylpyrrolidone is treated with complex hydrides, with or without further reaction of the modified polyvinylpyrrolidone with a reactive bifunctional compound, to give a polymer which has a molecular weight at least 2.5 times as great as that of the starting polymer.
摘要:
A process for the preparation of modified poly-N-vinylpyrrolid-2-one containing two identical reactive groups, wherein polyvinylpyrrolidone is treated with complex hydrides, with or without further reaction of the modified polyvinylpyrrolidone with a reactive bifunctional compound, to give a polymer which has a molecular weight at least 2.5 times as great as that of the starting polymer.
摘要:
Processes suitable for purifying aromatic-containing feed streams, and processes using such purified streams are described, wherein the purification processes comprise: (a) providing a process feedstream comprising an aromatic component; and (b) bringing the process feedstream into contact with a first zeolite and a second zeolite; wherein the first zeolite has a mean pore size of 0.3 to 0.5 nm, and wherein the second zeolite has a mean pore size of 0.6 to 0.8 nm.
摘要:
Processes suitable for purifying aromatic-containing feed streams, and processes using such purified streams are described, wherein the purification processes comprise: (a) providing a process feedstream comprising an aromatic component; and (b) bringing the process feedstream into contact with a first zeolite and a second zeolite; wherein the first zeolite has a mean pore size of 0.3 to 0.5 nm, and wherein the second zeolite has a mean pore size of 0.6 to 0.8 nm.
摘要:
Polymers which due to their physiological compatibility may be used in plasma substitutes and which essentially contain vinylpyrrolidone and .alpha.,.omega.-diisocyanato-alkanecarboxylic acid esters as structural units, their preparation, and plasma substitutes containing such polymers.
摘要:
A process for the preparation of high-viscosity polyvinylpyrrolidone, wherein an aqueous polyvinylpyrrolidone solution is subjected to a heat treatment in the presence of a water-insoluble peroxide and in the absence of oxygen, and thickeners containing the polyvinylpyrrolidone thus prepared.
摘要:
Readily water-soluble, slightly hygroscopic terpolymers which consist of(a) from 10 to 40% by weight of vinylpyrrolidone,(b) from 20 to 50% by weight of vinyl acetate (VAc) or vinyl propionate and(c) from 10 to 40% by weight of hydroxyethyl acrylate, hydroxypropyl acrylate or hydroxyethyl methacrylate, which terpolymers are used as auxiliaries in the cosmetics and pharmaceuticals sectors.
摘要:
A process for the preparation of polyvinylpyrrolidone-iodine, wherein a polyvinylpyrrolidone which has been subjected to hydrogenation is reacted with iodine in a conventional manner. The novel process is particularly suitable for use with low molecular weight polyvinylpyrrolidone, having a K value of from 10 to 20.