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Title:Characteristics and modeling of the fracture properties of polymer-silica microparticulate composites via macroscopic scratch tests
Author(s):Bouche, Gregory Alexander
Department / Program:Civil & Environmental Eng
Discipline:Civil Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):multi-phase composite
scratch test
fracture toughness
linear homogenization
Mori Tanaka
compressive strength
scratch hardness
macro scratch test device
SUNLab Macroscopic Scratch Test Device
micromechanics model
spherical inclusions
fracture energy
Young's modulus
linear elastic fracture mechanics
glass bead
paraffin wax
coupling agent
inclusion content
Abstract:The advantages of multi-phase materials are exploited in many industries, such as reinforced concrete in bridge construction, heterogeneous geological materials in petroleum engineering, advanced carbon fiber composites in aerospace engineering, and novel corrosion resistant coatings in the automotive industry. Although it is well known that the addition of inclusions can lead to improved multi-phase material properties, the characterization and prediction of these material properties is of current research interest. In this thesis, we evaluate the effect of spherical inclusion content on the material properties of polymer-silica microcomposites, both experimentally and theoretically. A wax mixture with spherical glass bead inclusions is developed as a model material. The hardness and fracture toughness of composites containing 0%, 5%, 10%, and 20% spherical glass bead inclusions by volume are analyzed using a built-in- house macroscopic scratch test device. The elastic modulus and compressive strength are obtained from a series of compression tests. Scanning electron microscopy is employed as an independent means to corroborate the morphology of the specimens. Several types of spherical glass beads with mean inclusion sizes of 20 μm and 200 μm are used in this study, and the effect of using a coating agent is investigated. We find that the compressive strength, elastic modulus, fracture toughness, and scratch hardness tend to increase with inclusion content. The composites containing coated glass beads exhibit superior properties in certain cases. Next, a rigorous linear elastic homogenization technique is derived to account for the observed change in elastic modulus and fracture toughness with inclusion content. The predictions developed are in strong agreement with the experimental data, creating a powerful tool for estimating the material properties of polymer-silica microcomposites. The generality of our theoretical framework makes it applicable to the study and prediction of elastic properties and fracture resistance in advanced composites.
Issue Date:2015-04-28
Rights Information:Copyright 2015 Gregory Bouche
Date Available in IDEALS:2015-11-17
Date Deposited:2015-05

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