Evidence for phase transitions of aqueous gelatin gels in a centrifugal field
2002, Borchard, W., Cölfen, Helmut, Kisters, D., Straatmann, A.
Experimental findings of turbid zones in the schlieren patterns of gels in a centrifugal field are explained by a demixing of gels into a highly swollen gel coexisting with a collapsed gel. The thermodynamic analysis of a slightly cross-linked aqueous gel at relatively low centrifugal field, which remains clear, leads to the conclusion that the system is close to its stability limit. A procedure is proposed to show how the stability limits may be extrapo lated by means of ultracentrifugal measurements. The phenomena are separated into a transient and a permanent demixing. The permanent demixing has been qualitatively explained by use of state diagrams predicted recently by Khokhlov and coworkers, Ilavsky and also by Moerkerke et al.