Enzymatic degradation of bacteriostatic polylactide composites

The work describes the effect of three types of polyhexamethylene guanidine (PHMG) derivatives on the enzymatic degradation of polylactide (PLA) based composites. In order to evaluate the degradation process caused by proteinase K, analyses of mass loss, of changes in the geometric structure of the surface and in thermal properties were determined. It has been established that the most significant mass loss was observed in the case of a composite film containing PHMG stearate (S), while the lowest was in relation to the sample containing PHMG granular polyethylene wax. The surface images of the individual samples, obtained by means of a scanning electron microscopy (SEM), clearly show changes in the surface of the studied materials after proteinase K treatment. Moreover the differential scanning calorimetry indicates that the type of PHMG derivatives strongly influences the degradation process. Results obtained from the performed analyses have shown that the presence of PHMG derivatives can affect the decomposition process of PLA.