Crystallization and enzymatic hydrolysis of PLA grade for orthopedics

Abstract

AbstractPoly(lactic acid) (PLA) absorbable reinforcement ligaments that are used in orthopedics for the repair and reinforcement of articulation instabilities as well as PLA samples synthesized in the laboratory were studied with respect to their thermal properties, crystallization kinetics, mechanical properties, and enzymatic hydrolysis. For these purposes, thermogravimetric analysis, differential scanning calorimetry (DSC), step‐scan modulated temperature DSC, hot stage polarized light microscopy (PLM), scanning electron microscopy, tensile testing, and enzymatic hydrolysis experiments were performed on both cases of samples and findings were compared. The PLA ligament showed higher tensile properties and higher crystallization rates under both isothermal and nonisothermal conditions. Isothermal crystallization and cold crystallization kinetics were studied using various models. The effective energy barrier of nonisothermal crystallization was also evaluated using the isoconversional method of Friedman. The generated morphology in the case of isothermal crystallization was observed with the use of PLM, and the spherulite growth rates were calculated. Finally, both materials showed very slow enzymatic degradation rates, although in the case of the reinforcement ligament they were substantially higher compared to the laboratory PLA sample. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 29:280–299, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.20194