Open Cell Microcellular Foams of Polylactic Acid (PLA)-based Blends with Semi-Interpenetrating Polymer Networks

Microcellular biodegradable polymer foam with an open porous structure was prepared from amorphous poly-L, D-lactic acid (P L, D LA) blended with polystyrene (PS), or polymethyl methacrylate (PMMA). The blends were prepared by polymerizing either styrene or methyl methacrylate (MMA) in a P L, D LA matrix. The styrene and MMA monomers are good cell-opening agents and constituents for an IPN. Pressure-quench batch foaming was conducted using carbon dioxide as a foaming agent at 80 degrees C under 10 MPa. The effects of monomers and a cross-linking agent on the foamability and OCC were investigated. Manipulation of the monomer and the cross-linking agent concentrations was able to change the viscoelasticity and partial miscibility of the blend and control the cell size at the micron scale as well as open pore content in the range of 20-90%.