23-03-2012, 11:45 AM
CHARACTERIZATION OF POLY-BASED NANOCOMPOSITES ENHANCED WITH CARBON NANOTUBES
CHARACTERIZATION OF POLY(METHYL METHACRYLATE BASED NANOCOMPOSITES.pdf (Size: 2.33 MB / Downloads: 38)
Introduction
In order to predict the ultimate properties of nanotube-loaded polymer composites
it is necessary to understand the nature of the polymer-nanotube interaction, and the
extent to which the presence of the nanotubes perturbs the properties of the polymer
matrix. The addition of nanoscale filler into polymer composites has been shown to
create impressive enhancements in the electrical, mechanical and thermal properties of
the resulting matrix.[7] The focus of this study is to gain an understanding of the
influence that carbon nanotube surface chemistry has on polymer-filler interactions and
the corresponding enhancement of the macroscopic properties. Insight into the relations
between preparation method, nanotube dispersion and interfacial interactions, and their
effect on bulk performance, is vital for formulating nanocomposites with the most
advantageous properties. Poly(methyl methacrylate) [PMMA] was selected as the matrix
polymer for this study due to its amorphous character (thereby avoiding potential
complications related to crystallization), and its suitability for a wide range of production
and processing techniques.
Polymer Matrix
Polymers are comprised of repeating structural segments and are found in a wide
variety of everyday products. PMMA is a glassy amorphous polymer, with a glass
transition temperature of ~100oC. Due to its diverse range of applications and potential
end-use environments, PMMA has been the subject of numerous nanocomposite studies
focusing on the improvement of strength and durability.[3, 5-6, 8]
Fillers for Polymer Nanocomposites
For a substantial number of applications, polymers are improved with additives or
fillers. Fillers are incorporated into the polymer matrix for many uses including
enhancement of processing and physical properties, and to add color. The addition of
these fillers allows a single polymer to be adapted for many diverse purposes based solely
on the material added to the matrix. For example, PMMA, since it is used in many
applications that demand high optical quality, requires a filler to increase strength and
toughness without masking its optical properties. In one such study, MgCl2 was used as
the filler creating a PMMA composite that would be suitable for use as an optical
sensor[9].
Polymer Nanocomposites
Polymer nanocomposites are defined as materials whose major component is a
polymer and the minor component must have a single dimension below 100 nm. Polymer
nanocomposites have become an active field of study in recent years because there have
been accounts of large property changes with very small additions of nanofiller (less than
5 wt%). As with traditional composites, the most important element of the system is the
interface. The interface is defined as the region in the vicinity of the filler surface where
polymer properties are altered in comparison with the bulk.[12] The goal of
understanding the interface between the nanofiller and the polymer is crucial for being
able to optimize the properties for a particular function.