Quantitative TEM tomography of Poly lactic acid/clay nanocomposites for a better comprehension of processing-microstructure-properties relationship

Abstract

The physicochemical properties of polymer nanocomposites (such as polymer/clay systems) are dependent on the properties of the polymer and filler, the reinforcement dimensionality, dispersion and orientation, and the nature of the interface between filler and matrix. Hence, thoroughly characterizing the morphology of those materials can lead to a better understanding of the behaviour of the final product and to improved design tools. The objective of performing TEM tomoghraphy (TEMT) on Poly lactic acid(PLA)/clay samples is to characterize their 3D microstructure, by obtaining the dispersion, distribution and orientation of the dimensions of the clays. This information cannot be elucidated from a qualitative TEM analysis or from conventional characterization techniques such as X-Ray diffraction. To carry out this work, nanocomposites obtained by extruding a PLA matrix and Cloisite 30B clays are used. The nanocomposites are obtained by using different extrusion shear rates. Shear rate favours the exfoliation of the clay particles and their dispersion, leading to nanocomposites with different microstructures and properties. Then, quantitative TEMT is performed to all the nanocomposites and the resulting 3D quantitative characterization is used for the comprehension of the mechanical behaviour of the nanocomposites.

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