In this study, for the first time, we developed microcellular PLA bead foams with double crystal melting peak structure followed by steam-chest molding of the foamed beads. The generated high melting temperature crystals during the saturation significantly affected the expansion ratio and cell density of the PLA bead foams by enhancing the PLA's melt strength and promoting heterogeneous cell nucleation around the crystals. The tensile mechanical properties of the molded EPLA bead foams showed that EPLA bead foams with double melting peak structure can be a promising substitute not only for EPS products but also for expanded polypropylene (EPP) products.
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