Polymer-layered silicate nanocomposites have become an important area studied
more widely in academic, government and industrial laboratories. These types of
materials were first reported as early as 1950 (Dennis et al., 2001). However, it was not
widespread until the period of investigation on this type of structures by Toyota researchers
(Kojima et al., 1993a and 1993b; Yano et
al., 1993; and Messersmith and Giannelis, 1995).
This early work of Toyota group was based on the formation of nanocomposites
where montmorillonite was intercalated with e-caprolactam in situ. Polymeric materials can
be filled with several inorganic and/or natural compounds in order to get a wide array
of property enhancements, e.g., increased stiffness and strength, improved solvent and
UV resistance, greater dimensional stability, decreased electrical conductivity and
enhanced gas barrier properties. The property improvements of clay-based nanocomposites
are due to the nanoscale nature of the formed system resulting in very high surface
areas. From an industrial approach, owing to high costs of development, synthesis
and commercialization of new polymers, most researchers look for new materials by
reinforcing or blending existing polymers so that tailor-made properties of the materials can be
achieved (Guozhen et al., 2002).
Poly (Ethylene Terephthalate) (PET) is a low-cost, high
performance thermoplastic that finds use in a variety of applications, such as fabrics and soft
drink bottles, reinforcement of tyres and rubbery goods, and food and beverage packaging.
PET has excellent surface characteristics and high heat deflection temperature. PET
regrinds from post consumer soft drink bottles have slightly reduced molecular weight and
structure related properties as compared to the pure polymer. In this study, the aim is to
produce nanocomposite materials from recycled PET (rPET) regrinds as the matrix with the
addition of organically Modified Montmorillonite (MMT) clays as fillers and observe the effects
of clay content and clay type on sample resistivity and dielectric properties.
Experiments were carried out with three different types of montmorillonites, namely,
Cloisite 30B, 15A and 25A. These organoclay structures show variations in selection according
to their degree of polarity. There is an increase in relative product hydrophobicity and a
decrease in product polarity in the order of 30B, 25A and 15A. Thus, the hydrophobicity resulted
from different natures of organic modifiers affects the
chemical compatibility between the polymer and the filler. Table
1 describes the product properties of these clay types. |
