Highly-Porous Plasticized Polylactide Foams with Bi-modal Structure Prepared via a Combined Economical Process: Processing-Morphology-Performance Correlations

Abstract

In this work, highly porous biodegradable poly(lactic acid) (PLA) foams with bi-modal architecture were prepared by using the melt-compounding process in a twin-screw extruder and filler leaching technique. The highly-filled composites of PLA/salt porogen were extruded and then, subjected to distilled water to obtain lightweight inter-connected nano- and micro-cellular structure for foams with 100% open cell content. The density of PLA diminished from 1.14 g/cm³ to 0.3 g/cm³ by using these simple and economical preparation methods. In the presence of poly(ethylene glycol) (PEG) plasticizer, the void content of open-cell PLA foam reached 72%. The bi-modal cell size distribution of foams was created by the partial miscibility of PLA/PEG phase and salt. The cell density of prepared foams rose to 6 × 10⁷ cells/cm³ by adding 15 wt% PEG to the PLA melt. The presence of PEG in the PLA melt affected the microstructure and mechanical properties of foams by altering the melt viscosity and surface tension. These open-cell bi-modal porous foams, which are biocompatible and biodegradable, can be applied in biomedical and pollutant adsorption applications. The adsorption capacities of the open-cell foams were measured for different solvents and marine pollutants. The adsorption capacity of these foams reached 4 g/g for carbon tetrachloride.