Characterization of crosslinked guar by thermal analysis

Guar gum (GG) was crosslinked with increasing amounts of glutaraldehyde (GA). The resulting crosslinked products were analyzed by differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and wide-angle X-ray diffraction (WAXD) to determine the influence of crosslinking on the polysaccharide structure. Each crosslinked product thermogram was characterized by two or three sharp endothermic peaks and a wide exothermic peak, with the latter indicating that a decomposition chain reaction occurred. It was observed that: (a) crosslinking altered the structure of GG; (b) the thermal stability of crosslinked GG depended on the amount of GA used with excess amount of the crosslinker reducing the stability of crosslinked GG; (c) the reaction of GG with GA occurred either by inter- or intra-crosslinking, depending on the amount of GA used; (d) crosslinking of GG with GA resulted in the formation of new regions in the polysaccharide, characterized by modified structures, whose abundance and density were crosslinker concentration dependent.