Fabrication of Poly(lactic acid)/Graphene Oxide Foams with Highly Oriented and Elongated Cell Structure via Unidirectional Foaming Using Supercritical Carbon Dioxide

Abstract

The significant influence of graphene oxide (GO) on the unidirectional foaming of poly(lactic acid) (PLA) using supercritical CO 2 as blowing agent was investigated in this study for the first time. Highly oriented and elongated cell structures were obtained from the PLA/GO nanocomposites foams. The thermal, rheological, and CO 2 absorption properties of the PLA/ GO nanocomposites were studied to investigate the effect of GO on PLA unidirectional foaming. It was found that the incorporation of GO improved the storage modulus, loss modulus, and complex viscosity of the PLA/GO nanocomposites significantly. The addition of GO improved the CO 2 absorption ability of the nanocomposites, which caused high expansion ratio and increased average cell size during foaming process. The high expansion force by enhanced CO 2 absorption, high matrix viscosity of PLA/GO nanocomposites, and restriction of the mold in three directions together caused the formation of the highly elongated cell structure during foaming.

Investigation of poly(l-lactic acid)/graphene oxide composites crystallization and nanopore foaming behaviors via supercritical carbon dioxide low temperature foaming

“…8(e)], the size of the pores was larger compared with that of PLA-0.1 and PLA-0.5. Kuang 30 reported that the CO 2 To understand the crystallization mechanism in PLA/ GO nanocomposites in detail, the interactions between PLA and GO and the mobility of PLA chains were investigated by Raman spectroscopy. As seen in Fig.…”

“…Microcellular foaming, using environmentally friendly supercritical carbon dioxide (SC-CO 2 ) as a physical foaming agent, was a promising method to prepare porous materials. [30][31][32][33] As a semicrystalline polymer, PLA possessed crystalline and amorphous regions. The crystallinity can be improved by the addition of GO.…”

Supercritical processing of CO 2 -philic polyhedral oligomeric silsesquioxane (POSS)-poly( l -lactic acid) composites

“…Additionally, PLA is widely used in biomedical applications, such as matrix for controlled release drug delivery systems, scaffolds for bone tissue engineering, and artificial vasculature due to its biocompatible and biodegradable nature [8][9][10][11][12][13]. PLA is a racemic mixture of L-and D-isomers and the final properties depend on the ratio of these isomers present in the structure.…”

Improved crystallizability and processability of ultra high molecular weight polyethylene modified by poly(amido amine) dendrimers

“…The degree of crystallinity ( ) of blends were determined by Eq . as follows : where, is the heat of fusion of the UHMWPE sample obtained by the DSC curves. is the enthalpy of 100% crystalline UHMWPE sample, which is 291 J/g for the UHMWPE sample used in this study.…”