Characterization and Thermal Properties of Polygenipin-crosslinked Hide Powders

Abstract

Genipin is a naturally occurring iridoid compound, it is widelyused as an ideal biological protein crosslinking agent due to itslow toxicity compared to glutaraldehyde and formaldehyde.Under alkaline condition, genipin could undergo ring-openingpolymerization via nucleophilic attack of hydroxyl ions followedby an aldol condensation. Because of the fact that polygenipincould create long-range intermolecular crosslinking betweenprotein chains, preliminary investigations have been carried outto study effect of polygenipin crosslinking on color and thermalstability of hide powder by using colorimetry, differentialscanning calorimetry (DSC) and thermogravimetric analysis(TGA). The results show that the peak denaturation temperature(Tp) for hide powders obtained from DSC increased to amaximum and then decreased with increasing of the molecularweight of polygenipin. Degree of crosslinking was evaluated,and the results suggest that thermal stability of hide powder isinfluenced not only by degree of crosslinking, but also by thetype of crosslinking. Thermogravimetric analysis also confirmsthat long-range intermolecular crosslink bridges formedbetween collagen molecules results in more thermally stable hidepowders. This study suggests that polygenipin can be potentiallyuseful in producing eco-friendly leather.