CHARACTERIZATION OF CROSS-LINKS INTRODUCED IN GELATIN

A method for the determination of the effectiveness of gelatin hardene rs was proposed. Formaldehyde(FA) and 1,3-bis (vinylsulfonyl)-2-propan ol (BVSP) were used as cross-linking agents for the hardening of gelat in. The cross-linked gelatin showed a typical rubber elasticity in a s wollen state with a mixed solution composed of concentrated aqueous Li Br and diethylene glycol monoalkyl ether. The energy components to tot al retractive forces were below 0.3. The amount of intermolecular cros slinks was estimated by applying an usual rubber elasticity theory for the swollen samples. The number of cross-linking sites was also deter mined by the amino acid analysis of BVSP cross-linked gelatin. The cro ss-linking efficiency for the reaction of BVSP occurring in a casting film with less swelling conditions was about four times higher than in a swollen gel. Approximately 92% or more of BVSP used was reacted wit h the free amino groups of lysine and arginine residues. There was a s ignificant difference between the reactivities of these amino groups. The amino groups of lysine residues were more reactive than those of a rginine in a gel state; the reactivities, however, reversed in a thin layer of wet film. The effectiveness of FA was extremely low. (C) 1997 John Wiley & Sons, Inc.