Hydrolytic degradation behavior of poly(l-lactide)/SiO2 composites

In this work, different contents of nano-silica (SiO2) particles were introduced into poly(l-lactide) (PLLA) to prepare PLLA/SiO2 composites though a two-step compounding method, i.e. solution compounding (preparing master batch) and subsequent melt compounding (master batch dilution). The dispersion of SiO2 was characterized using scanning electron microscope (SEM). The hydrophilicity of the material was evaluated by measuring the contact angle of water on the sample surface. The hydrolytic degradation measurements of the nanocomposites were carried out in alkaline solution at two different temperatures, i.e. 37 and 55 °C. Subsequently, microstructure evolution of PLLA matrix during the hydrolytic degradation process was systematically investigated using wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). The results showed that SiO2 had good dispersion in the PLLA matrix. Largely enhanced hydrolytic degradation ability was achieved for PLLA/SiO2 composites. Increasing the content of SiO2 or enhancing the hydrolytic degradation temperature accelerated the hydrolytic degradation of PLLA matrix. Further results showed that SiO2 promoted the reorganization of microstructure of PLLLA matrix during the hydrolytic degradation process.