Mechanical Properties of Boehmite Evaluated by Atomic Force Microscopy Experiments and Molecular Dynamic Finite Element Simulations

J Fankhänel,B Daum,A Kempe,H Sturm,M Ghasem Zadeh Khorasani,R Rolfes,D Silbernagl

doi:10.1155/2016/5017213

Abstract

Boehmite nanoparticles show great potential in improving mechanical properties of fiber reinforced polymers. In order to predict the properties of nanocomposites, knowledge about the material parameters of the constituent phases, including the boehmite particles, is crucial. In this study, the mechanical behavior of boehmite is investigated using Atomic Force Microscopy (AFM) experiments and Molecular Dynamic Finite Element Method (MDFEM) simulations. Young’s modulus of the perfect crystalline boehmite nanoparticles is derived from numerical AFM simulations. Results of AFM experiments on boehmite nanoparticles deviate significantly. Possible causes are identified by experiments on complementary types of boehmite, that is, geological and hydrothermally synthesized samples, and further simulations of imperfect crystals and combined boehmite/epoxy models. Under certain circumstances, the mechanical behavior of boehmite was found to be dominated by inelastic effects that are discussed in detail in the present work. The studies are substantiated with accompanying X-ray diffraction and Raman experiments.

Highlights

Aluminum oxides exhibit a wide range of commercial applications and are commonly used as a material for the reinforcement phase of nanocomposites (e.g., Chen et al [1], Horch et al [2], and Pradhan et al [3])
The results presented in the following are the outcome of computational studies simulating an Atomic Force Microscopy (AFM) force-distance curves (FDC) measurement on a pure boehmite crystal structure and combined boehmite-epoxy structures, respectively
Molecular Dynamic Finite Element Method (MDFEM) simulations on bulk boehmite presented in Section 4.3 yielded anisotropic Young’s moduli of 232 GPa, 136 GPa, and 267 GPa in the directions [100], [010], and [001], respectively

Summary

Introduction

Aluminum oxides exhibit a wide range of commercial applications and are commonly used as a material for the reinforcement phase of nanocomposites (e.g., Chen et al [1], Horch et al [2], and Pradhan et al [3]). Arlt [4] showed that unmodified and taurine modified boehmite nanoparticles are able to improve matrix-dominated properties of carbon fiber/epoxy composites, like shear strength, shear modulus, compressive strength, or compression after impact resistance by 10 to 25%. Shahid et al [7] investigated boehmite particles with different surface modifications (lysine and para-hydroxybenzoate) in a carbon fiber/epoxy composite and reported an increase of tensile and flexural properties for very small particle fractions (

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Conclusion