Microscopic observation and micromechanical modeling to predict the enhanced mechanical properties of multi-walled carbon nanotubes reinforced crosslinked high density polyethylene

摘要

In this work, the significantly improved mechanical performance of crosslinked high density polyethylene reinforced with multi-walled carbon nanotubes (MWCNTs) is examined. The combined results of tensile properties, scanning and transmission electron microscopy (SEM, TEM) and micro-Raman spectroscopy revealed a major turning point of the elastic and deformation behavior of these composites as a consequence of filler content. This experimentally detected behavioral turning point inspired the use of various micro-mechanical models for the prediction of the composites' elastic behavior. A modern three-phase approach accounting for the matrix, aggregated and finely dispersed filler states adequately describes the experimental data below the turning point, while for higher concentrations, a standard two-phase model is selected to describe the nanocomposites' elastic behavior. The selectedmodels successfully predicted the exact point of the behavioral transition while highlighting the necessity to use conventional along with modern experimentally-driven methods. Based on the combination of microscopic observations and micro-Raman analysis, it is suggested that the observed and modeled change in the mechanical behavior occurs as a consequence of two competitive mechanisms governing the incorporation of MWCNTs in PEX: a tendency to enhance its mechanical properties by successful load transfer and a drive to form bundles, reducing this positive effect.