Carbon nanomaterial/polymer composites with enhanced electrical and mechanical properties
Carbon nanomaterial is a class of materials built by a cluster of sp2- hybridized carbon atoms in different geometries, including zero-dimensional (0D) fullerenes, 1D carbon nanotubes (CNTs), and 2D graphene. A unique combination of large aspect ratio, high specific surface area, low densit...
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sg-ntu-dr.10356-512472023-03-11T17:26:56Z Carbon nanomaterial/polymer composites with enhanced electrical and mechanical properties Pan, Yongzheng Li Lin School of Mechanical and Aerospace Engineering DRNTU::Engineering::Materials::Composite materials Carbon nanomaterial is a class of materials built by a cluster of sp2- hybridized carbon atoms in different geometries, including zero-dimensional (0D) fullerenes, 1D carbon nanotubes (CNTs), and 2D graphene. A unique combination of large aspect ratio, high specific surface area, low density, and excellent mechanical, electrical and thermal properties makes them multi-functional nanofillers for light-weight and high-performance polymer composites. The main objective of this research is two-fold: i) development of effective routes for fabrication of polymer composites containing carbon nanomaterials with enhanced electrical and mechanical properties and ii) comprehension of the relationships among processing, structure and property of the carbon nanomateiral/polymer composites. First, the influence of dispersion of multi-walled carbon nanotube (MWCNT) on the electrical properties of MWCNT/polypropylene (PP) composite is studied. To improve the dispersion of MWCNTs, MWCNTs are chemically oxidized and a polymeric compatibilizer, maleic anhydride-grafted polypropylene (PP-g-MA), is added into the composites. It is revealed that oxidation of MWCNTs marginally improves the dispersion but largely enhances the interfacial adhesion between MWCNTs and the PP matrix in the presence of PP-g-MA. Because the improved MWCNT dispersion reduces the number of electrical contacts between MWCNTs, the composites containing both oxidized MWCNTs and PP-g-MA have the best dispersion and distribution of MWCNTs but exhibit lower electrical conductivity compared with the pristine MWCNT/PP composites. Therefore, it is crucial to balance between the MWCNT dispersion and their connections into conductive networks. Afterwards, the influence of the aspect ratio of MWCNTs is investigated. The MWCNT/PP composites display a synchronous increase in electrical conductivity with increasing aspect ratio of MWCNTs at a fixed MWCNT loading. MWCNTs with a larger aspect ratio also lead to a lower percolation threshold of the composites. By adding MWCNTs with an aspect ratio of 167, the composites exhibit an electrical percolation threshold of only 0.74 wt.% and reach an electrical conductivity of 1.2 S/cm at 10 wt.% loading of MWCNTs, which is higher than the conductivities reported in the previous literature for MWCNT/PP systems. Meanwhile, dynamic rheological properties of the composites are measured for investigating their percolation and gel-like behavior. The difference between rheological and electrical percolation thresholds is discussed and explained by the different stages of MWCNT network formation. Doctor of Philosophy (MAE) 2013-03-13T09:08:11Z 2013-03-13T09:08:11Z 2013 2013 Thesis http://hdl.handle.net/10356/51247 en 227 p. application/pdf |
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DRNTU::Engineering::Materials::Composite materials Pan, Yongzheng Carbon nanomaterial/polymer composites with enhanced electrical and mechanical properties |
description |
Carbon nanomaterial is a class of materials built by a cluster of sp2-
hybridized carbon atoms in different geometries, including zero-dimensional (0D)
fullerenes, 1D carbon nanotubes (CNTs), and 2D graphene. A unique combination
of large aspect ratio, high specific surface area, low density, and excellent
mechanical, electrical and thermal properties makes them multi-functional
nanofillers for light-weight and high-performance polymer composites. The main
objective of this research is two-fold: i) development of effective routes for
fabrication of polymer composites containing carbon nanomaterials with enhanced
electrical and mechanical properties and ii) comprehension of the relationships
among processing, structure and property of the carbon nanomateiral/polymer
composites.
First, the influence of dispersion of multi-walled carbon nanotube
(MWCNT) on the electrical properties of MWCNT/polypropylene (PP) composite
is studied. To improve the dispersion of MWCNTs, MWCNTs are chemically
oxidized and a polymeric compatibilizer, maleic anhydride-grafted polypropylene
(PP-g-MA), is added into the composites. It is revealed that oxidation of MWCNTs
marginally improves the dispersion but largely enhances the interfacial adhesion
between MWCNTs and the PP matrix in the presence of PP-g-MA. Because the
improved MWCNT dispersion reduces the number of electrical contacts between
MWCNTs, the composites containing both oxidized MWCNTs and PP-g-MA have
the best dispersion and distribution of MWCNTs but exhibit lower electrical conductivity compared with the pristine MWCNT/PP composites. Therefore, it is
crucial to balance between the MWCNT dispersion and their connections into
conductive networks. Afterwards, the influence of the aspect ratio of MWCNTs is
investigated. The MWCNT/PP composites display a synchronous increase in
electrical conductivity with increasing aspect ratio of MWCNTs at a fixed
MWCNT loading. MWCNTs with a larger aspect ratio also lead to a lower
percolation threshold of the composites. By adding MWCNTs with an aspect ratio
of 167, the composites exhibit an electrical percolation threshold of only 0.74 wt.%
and reach an electrical conductivity of 1.2 S/cm at 10 wt.% loading of MWCNTs,
which is higher than the conductivities reported in the previous literature for
MWCNT/PP systems. Meanwhile, dynamic rheological properties of the
composites are measured for investigating their percolation and gel-like behavior.
The difference between rheological and electrical percolation thresholds is
discussed and explained by the different stages of MWCNT network formation. |
author2 |
Li Lin |
author_facet |
Li Lin Pan, Yongzheng |
format |
Theses and Dissertations |
author |
Pan, Yongzheng |
author_sort |
Pan, Yongzheng |
title |
Carbon nanomaterial/polymer composites with enhanced electrical and mechanical properties |
title_short |
Carbon nanomaterial/polymer composites with enhanced electrical and mechanical properties |
title_full |
Carbon nanomaterial/polymer composites with enhanced electrical and mechanical properties |
title_fullStr |
Carbon nanomaterial/polymer composites with enhanced electrical and mechanical properties |
title_full_unstemmed |
Carbon nanomaterial/polymer composites with enhanced electrical and mechanical properties |
title_sort |
carbon nanomaterial/polymer composites with enhanced electrical and mechanical properties |
publishDate |
2013 |
url |
http://hdl.handle.net/10356/51247 |
_version_ |
1761781514221125632 |