| 摘要 |
The process for increasing the molecular weight of poly-N-vinylpyrrolidone over that normally obtained by suspension polymerization of N-vinylpyrrolidone in a saturated hydrocarbon suspension medium, by adding to the suspension medium a controlled amount of water, specifically an amount between about 1% and 35% by weight based on the total weight of N-vinylpyrrolidone monomer. The significantly higher molecular weight of the resulting polymeric product can be still further increased by additionally incorporating in the suspension medium between about 0.001 mol % and about 1 mol % of a difunctional vinyl cross-linking agent per mol of N-vinylpyrrolidone monomer. The polymeric products of the present invention are preferably water soluble granules having a porous structure; although the present invention also concerns the poly-N-vinylpyrrolidone having a number average molecular weight of between 400,000 and 2,000,000, preferably between 450,000 and 1,500,000 in any physical form.
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