Tensile properties
Effect of nanoclay types on tensile properties of pure agar and
agar/clay nanocomposite films compounded with 5% (w/w) of
different types of clay are shown in Table 4.
TS and E of pure agar
film were 29.7 ± 1.7 MPa and 45.3 ± 9.6%, respectively.
Tensile
test results indicate that the TS of the composite films except
agar/Cloisite Na+ films did not change significantly (P > 0.05)
after incorporation of nanoclay, but TS of agar/Cloisite Na+ films
increased about 18% after incorporation of nanoclay.
However,
the E of nanocomposite films did not show any significant change.
Usually, a well-developed polymer/clay nanocomposite results in
highly increased mechanical strength compared to the pure polymer
matrix, since uniform dispersion of the nano-sized clay particles
produces an ultra-high interfacial interaction and ionic bonds
between the nanoclay and host polymer (Alexandre and Dubois
2000; Pandey and others 2005; Sinha and Bousmina 2005; Rhim
and Ng 2007; Pavlidou and Papaspyrides 2008).
However, compounding
the MMT clays reduced the TS in the present study indicating that interaction between the organoclays and polymer
matrix is not well developed probably due to the organoclays
are not well dispersed in the polymer matrix.
Zeng and others
(2005) prepared the solvent cast agar/organoclay nanocomposite
and found through small and wide-angle X-ray scattering measurements
that the silicate layers could not be individually well
dispersed in the agar/clay blend.
Ku and others (2008) prepared
an edible film with agar-rich seaweed (Gelidium corneum) powder
and reported the TS and E of the film as 2.32 MPa and 28.96%,
respectively.