عنوان مقاله [English]
Poly lactic acid polymers are, biodegradable, with long strands of polymer and strong. Achieve water to high polymers bound, causes the band brake to acids are exist in the human body. These types of polymer in are used as holding medical science instead of platinum for broken bones. After the bone repair, the polymer decomposes and water and carbon dioxide which excreted from the body and does not need surgery again. The main goal was investigation of degradation mechanism, decomposition time and its effective factors. In this paper decomposition kinetic of biodegradable polymers in human body was studied, that is complicated due to its autocatalytic nature. Then the governing equations with boundary and initial conditions were solved numerically. Variation of product concentration, concentration of polymer bands and water were presented against exposure time. The time needed for complete decomposition was calculated equal to 11 months. That diffusion coefficient, water concentration and geometry affect the degradation. Finally recommendations for optimum use of these materials were presented.