| 摘要 |
A process is described for making highly crosslinked polyvinylpyrrolidone (PVP) polymer by popcorn polymerization having a swell volume of less than about 65 ml/10 g, preferably 40-65 ml/10 g, in the absence of added crosslinking agent, and with substantially no induction period. The process comprises (a) providing a reaction mixture of vinylpyrrolidone (VP) monomer at a concentration of about 75-85 % in an aqueous basic solution, containing about 0.4-0.8 % base, under agitation, in an inert gas atmosphere, and at an initial gas pressure of at least 2 bars, (b) heating said mixture at a predetermined temperature and time sufficient to generate an active crosslinker in situ, and (c) reducing the temperature of the mixture to a temperature whereupon popcorn polymerization of said VP monomer commences substantially immediately to form the desired crosslinked PVP. |
