Influence of graphene nanoplates and multiwall carbon nanotubes on rheology, structure, and properties relationship of poly (lactic acid)

In this study, rheology, structure, and mechanical properties are investigated in point of their enhancement by incorporation of graphene nanoplates (GNP) and multiwall carbon nanotubes (MWCNTs) in poly (lactic acid) matrix. PLA-based nanocomposites with 6% total amount of GNP and MWCNT in different combination, produced by melt extrusion method, are investigated. Incorporating of GNP to PLA at the binary nanocomposites and GNP and MWCNT (i.e. increasing of GNP concentration and an analogous decrease of MWCNT concentration) to PLA at the ternary nanocomposites leads to reduction of the linear viscoelastic range and critical strain. For pure molten polymer, a terminal-like behavior has been observed in low frequencies and the slope n is proportional to 2 (G0 ∼ ω n). From the results, we can observe that as the GNP concentration increases, n decreases gradually. All samples are characteristic as a “gel” type structure, which is usually associated with reaching the percolation threshold. We demonstrated that XRD can be used as a quick and unambiguous method to determine the homogeneity of the nanocomposites in terms of carbon filler dispersion in a polymer matrix. GNP and MWCNT addition improved the impact strength of PLA composites, which confirm the successful reinforced effect on polymer matrix of both fillers.