Polylactic acid (PLA) - Nano alumina composite polymer foams via combined solid state foaming and additive manufacturing

Abstract

Polylactic acid (PLA) is one of the most widely used thermoplastic. The goal of this study is to fabricate PLA-alumina nanocomposite foams via solid state foaming of additively manufactured structures for applications that require light weight material with higher strength. PLA - nano alumina suspensions with varying compositions were prepared by ultrasonic stirring followed by solvent extraction to obtain thin films. The thin films were subsequently fed into an extruder to obtain filament for 3D printing. The filament was used to print specimens with desired architectures which were subjected to solid state foaming to generate the porous structure. The foamed and un-foamed specimens were subjected to a tensile test using the ASTM D638 and ASTM D882 standard to study the effect of solvent (DCM, DMF), alumina percentage (0, 5, 10) and porosity on strength of the samples. Scanning electron microscopy was used to measure the average pore size of the foamed samples. The results showed that the addition of alumina improves the strength of foamed samples, however the percentage increase depends on the solvent. The maximum tensile strength of foamed 10 wt% alumina nano composites prepared using DCM was measured to be around 75% higher than pure PLA foams.