The improved foaming behavior of PLA caused by the enhanced rheology properties and crystallization behavior via synergistic effect of carbon nanotubes and graphene

Abstract Hybrid fillers are expected to improve the foaming behavior of polymer while little research concern about the synergetic effect of hybrid fillers on the foaming behavior of polylactide (PLA). In current work, rheological properties and crystallization behavior of PLA modified by hybrid fillers (carbon nanotubes [CNTs] and graphene [GP]) was studied, and the foaming morphologies and properties of composite foams were investigated. Results showed that the PLA/CNTs/GP composites exhibited better filler connection, which resulted in higher melt strength and increasing crystals nucleation sites. The increased melt strength and crystals in PLA/CNTs/GP helped the matrix to withstand the bubble growth, and the collapse and coalescence of bubbles was prevented. The better cell morphology of PLA/CNTs/GP presented better filler connection and resisted the external force, thus enhanced the electrical conductivity to 1.28 × 10 −1 S/m and compressive strength to 7.46 MPa for composite foams, which widened the application of PLA foams.