ISSN:
1435-1528
Keywords:
Gel point
;
gelation
;
physical gels
;
gelatin
;
guar/borate
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Abstract Three biopolymer systems which are commonly believed to yield physical gels are compared and contrasted in light of Winter's criterion for chemical gelation (tan (loss angle) becomes frequency independent). Biopolymer concentration is taken as the natural variable in the gelation process. The Xanthan gum system is found to yield a sol state up to a concentration of 3% with the gel-like symptoms arising as a result of separation of an anisotropic phase. Gelatin at 20 °C shows a gel point at 0.75% by the above criterion and otherwise behaves analogously to a chemically crosslinked network. Guar gum gelled with borate fails the gel criterion on our instrumental time scale because of the finite lifetime of the guar/borate linkage, here estimated to be in the range 10–100 s. On shorter time scales, however, this system appears to behave as a rubbery network.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00701120
Permalink
