MODIFIED ACRYLIC-BASED SUPERABSORBENT POLYMERS - EFFECT OF TEMPERATURE AND INITIATOR CONCENTRATION

A solution polymerization process was used industrially to produce sup erabsorbent polymers based on acrylic monomers. Using a simple, small scale laboratory version of the polymerization part of this process wh ich permits contact with air and evaporative losses, the effects of va rying the heat input and the initiator concentration were explored. Th e presence of oxygen resulted in an inhibition period which lengthened the time for completing polymerization and consequently increased eva porative losses of water. The absorbency of the reaction products was highest under conditions which gave short reaction times. Long reactio n times resulted in long inhibition periods, runaway polymerization an d low absorbency. These effects were accounted for in terms of oxygen participation in the polymerization and extensive losses of water as t he solvent. (C) 1998 Elsevier Science Ltd. All rights reserved.