Mixed Crystal Formation and Glassy Solidification in the System Gelatin-Water

Paper presented at a Symposium on “Photographic Gelatin”, organized by the Scientific and Technical Group of the Royal Photographic Society, held in Wadham College, Oxford on 2-6 September 1985.

Abstract

Calorimetric investigations of the system gelatin-water lead to the conclusion that the state diagram is of the eutectic type. At the invariant eutectic temperature ice, nearly pure water, and mixed crystal with an over-all concentration of 67% by wt gelatin coexist. The liquidus and the solidus curves have been determined up to temperatures very close to the melting point of pure gelatin at 510 K. The glassy solidification curve, which has been measured between a solution of 40% by wt and pure gelatin, is situated below but very close to the solidus. From the change of the cooling rate different non-equilibrium states can be verified leading to a second, morphologically caused glass transition, which does not correspond to the initial over¬all composition of the homogeneous phase. The phase behaviour is discussed with respect to the model proposed for collagen fibrils by Hosemann et al.

Notes

Paper presented at a Symposium on “Photographic Gelatin”, organized by the Scientific and Technical Group of the Royal Photographic Society, held in Wadham College, Oxford on 2-6 September 1985.