Mechanical and dielectrical properties of epoxy-Al2O3 nanoparticle composites

Other Title(s)

الخصائص الميكانيكية و العزلية لمتراكب Al2O3-EP جسيمات نانوية

Dissertant

Kazim, Muhammad Jawad Hadi

Thesis advisor

Abd Allah, Ahmad Qasim

University

University of Baghdad

Faculty

College of Science

Department

Department of Physics

University Country

Iraq

Degree

Master

Degree Date

2014

English Abstract

EP/Al2O3 nanoparticles composites were prepared using magnetic stirrer, ultrasonic homogenizer and vacuum system with different weight percentages (0.1, 0.2, 0.3, 0.4, 0.5, 1, 2, 3, 4, 5 and 7) % of Al2O3 nanoparticles, with an average particle size for nano Al2O3 is 46.73 nm measured by AFM techniques.

The Al2O3 nanoparticles identified crystal structure by using X-ray diffraction (XRD) and found it is ɣ-Al2O3 nanoparticles with cubic crystal structure.

The samples prepared by two methods; one without nitrogen flow included and second with nitrogen flow included in gloves box (handmade by researcher).

The second preparation method is preferred because it's not contain on air bubbles, dust, moisture and other unintended matter in polymer matrix can act as defects, which in turn can significantly influence on the mechanical and dielectrical properties of epoxy/Al2O3 nanocomposites So, we used the final preparation method for preparation the specimens and then tested it.

These samples are subjected to different techniques, Fourier Transform Infrared Spectroscopy (FTIR), Three Point Bending, Field Emission Scanning Electron Microscope (FE-SEM), Differential Scanning Calorimeter (DSC), and Dielectric Spectroscopy.

Fourier Transform infrared Spectroscopy (FTIR) of EP and EP/Al2O3 nanocomposites Shows that the addition of nanoparticles to epoxy does not result formation of new bonds, but interface theory predict that there is a strong bonding between nanoparticles and epoxy chains.

In order to get further insights, the surface chemistry of Al2O3 nanoparticles is also examined through FTIR spectroscopy and the spectrum showed that there is OH group on the nanoparticle surface this OH group can form hydrogen bond with polar molecules and this explain interface theory.

Three Point Bending test shows that flexural strength and young of EP/ Al2O3 nanocomposites were increased with increasing the weight percentage of Al2O3 nanoparticles.

Flexural strength maximum value was found for EP/Al2O3 nanocomposites at 4wt% of Al2O3 nanoparticle 89.73 MPa which was increased 42% comparing with epoxy.

Young modulus maximum value was found at 7wt% of Al2O3 nanoparticle 5.12 GPa which was increased 187% comparing with epoxy.

Field Emission Scanning Electron Microscope (FE-SEM) images for structured surface and fractured surface shows that morphology of structured of EP/ Al2O3 nanocomposites with minimum defect for EP/Al2O3 nanoparticles composites at 4wt% of Al2O3 nanoparticles.

While the morphologies of fractured surface showed that the smooth of the surface decreasing with the appeared tortuous crack and increased respectively with the increasing weight percentage of nanoparticle that resists the deformation.

Differential Scanning Calorimeter (DSC) shows that glass transitions temperature (Tg) for EP/Al2O3 nanocomposites were found maximum value at 4wt% of Al2O3 nanoparticles for concentration 3,٤ and 5wt% of Al2O3 nanoparticles.

Dielectric properties EP/Al2O3 nanocomposite showed that the relative permittivity of EP/Al2O3 nanocomposites at 1wt% is lowered than that of epoxy were decreased 1% comparing with epoxy.

The relative permittivity at 2, 3, and 4wt% of Al2O3 nanoparticle increased with increasing weight percentage of Al2O3 nanoparticles, respectively reached maximum at 4wt% which was 4.39 increased 14% comparing with epoxy at 1000Hz.

At 5 and 7wt% the relative permittivity decreased again.

Also, it was found the tan delta and conductivity decreased with increasing the nanoparticle contains reached minimum value for tan delta at 4wt% which was 0.0009 and its decreased 47% comparing with epoxy at 1000Hz.

Conductivity reached minimum value at 4wt% which was 0.000006(ohm.cm)-1 at 100000 Hz and its decreased 82% comparing with epoxy.

At 5 and 7wt% of Al2O3 nanoparticles tan delta and conductivity begin to increase again.

Main Subjects

Physics

Topics

• Mechanical properties

No. of Pages

94

Table of Contents

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-607103