Network defects in polyacrylamide gels

✍ Scribed by J. Baselga; M.A. Llorente; I. Hernández-Fuentes; I.F. Piérola

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 361 KB
• Volume: 25
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(89)90188-2

✦ Synopsis

The weight conversion at the gel point (~) was determined by the gas bubble method in two sets of polyacrylamide (PAA) gels crosslinked with N,N'-methylene-bisacrylamide (BA). ~t~ remained practically constant when the crosslinker ratio was C = 10% (w/w) and the total concentration of comonomers in the feed ranged from Cr = 5 to 10 g/100 ml. When CT was kept constant at 5 g/100 ml and C changed from 0 to 25% (w/w), ct~ showed a minimum at C = 7%. By comparing the experimental values of ct~ with those calculated for an ideal network, it was concluded that the crosslinking etiiciency of BA is very low. The dependence on C of ~t~ and other properties like the elastic phantom modulus, If~hl, and the polymer volume fraction at swelling equilibrium, v2~, was explained in terms of the formation of network defects: the formation of BA sequences longer than unity and that of intramolecular cycles both have an increasing contribution at C > 7% but can be neglected at lower values of C.