Thermal Analysis of Sustainable Polylactic Acid Foam Development

Polymer foams are an important class of materials, with applications in automotives, aerospace, leisure, insulation, and packaging. They are a more sustainable option compared to regular polymeric materials since they are less dense and use less material. These foams can be made more sustainable by using a bio-based polymer as the basis for the foam. The thermal characteristics of the necessary components for creating sustainable bio-based polymer foams were investigated. The base polymer that is used is polylactic acid (PLA). Different foaming formulations were made using exothermic, nitrogen-based chemical foaming agents (CFA). The CFA that were used were Axeleron and Tracel brand solid pellets, and Avient brand liquid CFA. Additionally, polymer crosslinking agents such as dicumyl peroxide (DCP) and tryallylisocyanurate (TAIC) were added to some of the formulations. These components were compounded with PLA via two solid-state processes: cryogenic milling and solid-state shear pulverization (SSSP). Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) were performed on pure, dried PLA pellets, each of the CFAs, and on TAIC and DCP to understand individual degradation temperatures and the foaming activation temperatures for each of the CFA. TGA and DSC were also conducted on the compounded formulations. Comparing the thermal properties of the foaming material formulations with individual material ultimately provides insight on the thermal tendencies of PLA foaming.