Modeling of the acoustic absorption of bi-modal polylactide foams

Abstract

In this study, highly porous bi-modal structures were designed and fabricated from polylactide (PLA) as the main structure and utilizing polyethylene glycol (PEG) to form micro pores by compression molding combined with particulate leaching technique. The pore size of the foam structure was controlled by salt particulates and higher interconnectivity was achieved by the co-continuous blending morphology of PLA matrix with water-soluble PEG. This fabrication method makes it possible to control pore geometry and interconnectivity closely and therefore is an ideal approach to study the relation between microstructure and acoustic properties of the foams. PLA is a bio-based thermoplastic polymer derived from renewable resources. Therefore, the resulting acoustic foams are benign and environmentally friendly. Fabricated foams were characterized based on cellular, acoustic, and mechanical properties. The acoustic performance of the foams was studied by measuring the normal incident absorption coefficient in accordance with the ASTM E1050 standard. An analytical model based on Johnson–Champoux–Allard model was used to numerically simulate the acoustic performance of foams under study. Numerical results predict the absorption behavior of PLA foams with high accuracy. Through this research, open porosities close to 90% were achieved, and the effect of water soluble polymer on cellular properties, acoustic and mechanical performance of polylactide foams was studied.