Abstract
The effect of selected plasticizers (triethyl citrate, ethyl pyruvate, methyl and ethyl salicylate, triacetin, tributyrin) on thermal and rheological properties of the oligoesters of DL-lactic and glycolic acids crosslinked with mannitol was studied. Plasticization of the oligoesters was performed by their fusion at 80 degrees C and subsequent mixing with a plasticizer in the concentration 20 %.
All plasticizers in this concentration were miscible with the oligoesters and the blends did not tend to phase separation. The efficiency of plasticizers was evaluated by lowering the glass transition temperature of the non-plasticized oligoester.
All the tested plasticizers proved to be effective. The plasticizers also induced a decrease in dynamic viscosity of the oligoester, which is necessary for the manufacture of oligoesters as drug delivery carriers applied by injection or topically as sprays.
Ethyl pyruvate was the most effective plasticizer of the DL-lactic and glycolic oligoesters crosslinked with mannitol.