Acrylamide ultrahigh molecular weight polymerization reaction initiator

Abstract

The invention an acrylamide ultrahigh molecular weight polymerization reaction initiator, which consists of 20-50 parts of methyl isobutyl ketone, 10-40 parts of 4-heptanone, 3-10 parts of dimethylfomamide, 10-30 parts of azobisvaleronitrile, 3-5 parts of azobisisobutyronitrile and 10-30 parts of dimethyl azobisisobutyrate. The invention relates to a composite initiator special for synthesizing ultrahigh molecular weight polyacrylamide, which is suitable for bulk kettle polymerization for industrially generating polyacrylamide. A plurality of initiators are compounded, a polymerization reaction is completed in a segmental initiating way, free radicals are released segmentally by different types of initiators with different activating energy at different reaction temperatures, certain concentration of the free radicals is kept, a polymerization reaction speed is controlled, and the molecular weight of a polymerized product can be increased effectively. Reaction activating energy differs, and segmental initiation is performed; the initiator is water-soluble, and a reaction is uniform; and the reaction is insensitive to acid and alkaline environments, and high adaptability is achieved.

Description

technical field [0001] The invention relates to a special composite initiator for synthesizing ultra-high molecular weight polyacrylamide, in particular to an acrylamide ultra-high molecular weight polymerization initiator, which is suitable for large-block still-type polymerization of polyacrylamide produced industrially. Background technique [0002] Acrylamide polymerization is a typical free radical polymerization. The chain length is inversely proportional to the square root of the initiator concentration, and the average degree of polymerization is directly proportional to the kinetic chain length. The amount of initiator has a significant impact on the average molecular weight of the polymer. The use of low-activity initiators can reduce the polymerization reaction speed. The polyacrylamide product has a large relative molecular mass, but the activity of the initiator is too low, too few free radicals are generated, and there are few active points for initiating monome...

AI Technical Summary

Problems solved by technology

Among traditional polymerization initiators, azo initiators have high reactivity, high decomposition temperature and fast decomposition speed, resulting in too fast polymerization

Especially in the later stage of the polymerization reaction, as the polymerization reaction releases a large amount of heat, the temperature of the reaction system rises sharply, which promotes the decomposition speed of the initiator, and the speed of the polymerization reaction is difficult to control.

In addition, some initiators are insoluble or slightly soluble in water, which makes them unable to be evenly distributed in the reaction system. During the polymerization reaction, the local initiator concentration will be too high and the reaction will be too fast.

At the same time, some initiators are greatly affected by the acid-base environment, resulting in unsatisfactory reactions or even no reaction.

At present, there is not much research on the synthesis initiator of ultra-high molecular weight polyacrylamide in China, and azobisisobutyronitrile is usually used, and the initiation temperature of azobisisobutyronitrile initiator is high and the reaction is difficult to control, which restricts the production of polyacrylamide. The improvement of molecular weight is mainly manifested in the high reaction activation energy of the traditional azobisisobutyronitrile initiator, which makes it difficult to initiate polymerization at low temperature. When the temperature rises, although it can be initiated normally, the reaction speed cannot be controlled, and the free radical concentration Increase rapidly, appearing in the middle and late stages of polymerization, but the speed should be too fast, which is not conducive to the formation of long molecular chains of polyacrylamide

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