112
The optical properties of the final nanocomposite may be affected due to the inefficient dispersion or distribution of the filler into the polymer matrix or the addition
of the filler at high concentrations (Unalan et al. 2014). The incompatibility between
biobased polymer and nano-filler leads to an inefficient distribution. On the other
hand, the filler volume fraction increases with high concentration of the filler, which
leads to a proportional increase in haze due to an increase in the dispersion centers
(Introzzi et al. 2012). The optical properties of these nanocomposites can thus be
controlled by selecting the appropriate filler and optimal processing conditions,
such as the processing period, temperature, energy requirement, concentration of
the fillers or other compounds, and the type of solvents. Biobased nanocomposites
with adequate transparency and UV-barrier properties are good candidates for coating applications such as wrapping for processed food products, or as multilayer
films, and containers (Shankar and Rhim 2016a).
6.5.4 Thermal Properties
The thermal stability of biobased polymer is another important aspect to be considered, especially to be able to process at an elevated temperature without degradation. Thermally stable biobased nanocomposites can be synthesized by
solution-based methods in aqueous medium, where the final degradation occurs at
higher temperature compared to pristine biopolymers. Nano-fillers have a higher E
and a lower thermal expansion coefficient compared to the polymers, thus the addition of these fillers provide thermal stability to biobased polymers (Yoon et al.
2002). As a rule, the temperature, types and concentration of nano-filler play an
important role on the thermal stability of polymer nanocomposites (Pavlidou and
Papaspyrides 2008). There are three steps for decomposition patterns (Swain et al.
2018). In the first step, all materials begin to lose adsorbed water (free water or
available water) at about 100 °C. Partial thermal decomposition of the biobased
nanocomposite occurs in the second step, while in the third step, it produces the
complete decomposition and oxidation. The nano-fillers improve the thermal stability of biobased nanocomposites with two main functions called barrier effect
and catalytic effect against the polymer degradation (Zhao et al. 2005). In general,
the dispersed crystalline nano- fillers behave as an insulator for heat transfer and a
barrier against the diffusion of the volatile compounds formed during thermal
decomposition. Nano-fillers increase the thermal stability of the polymer under
oxidative conditions through its oxygen barrier properties (Pavlidou and
Papaspyrides, 2008).
6.5.5 Surface Properties
The incorporation of nano-fillers into biopolymers can also affect the surface properties of the final material. The surface properties have a key role in food packaging
applications, such as printing, lamination and co-extrusion. The addition of filler
H. Cakmak and E. Sogut
The optical properties of the final nanocomposite may be affected due to the inefficient dispersion or distribution of the filler into the polymer matrix or the addition
of the filler at high concentrations (Unalan et al. 2014). The incompatibility between
biobased polymer and nano-filler leads to an inefficient distribution. On the other
hand, the filler volume fraction increases with high concentration of the filler, which
leads to a proportional increase in haze due to an increase in the dispersion centers
(Introzzi et al. 2012). The optical properties of these nanocomposites can thus be
controlled by selecting the appropriate filler and optimal processing conditions,
such as the processing period, temperature, energy requirement, concentration of
the fillers or other compounds, and the type of solvents. Biobased nanocomposites
with adequate transparency and UV-barrier properties are good candidates for coating applications such as wrapping for processed food products, or as multilayer
films, and containers (Shankar and Rhim 2016a).
6.5.4 Thermal Properties
The thermal stability of biobased polymer is another important aspect to be considered, especially to be able to process at an elevated temperature without degradation. Thermally stable biobased nanocomposites can be synthesized by
solution-based methods in aqueous medium, where the final degradation occurs at
higher temperature compared to pristine biopolymers. Nano-fillers have a higher E
and a lower thermal expansion coefficient compared to the polymers, thus the addition of these fillers provide thermal stability to biobased polymers (Yoon et al.
2002). As a rule, the temperature, types and concentration of nano-filler play an
important role on the thermal stability of polymer nanocomposites (Pavlidou and
Papaspyrides 2008). There are three steps for decomposition patterns (Swain et al.
2018). In the first step, all materials begin to lose adsorbed water (free water or
available water) at about 100 °C. Partial thermal decomposition of the biobased
nanocomposite occurs in the second step, while in the third step, it produces the
complete decomposition and oxidation. The nano-fillers improve the thermal stability of biobased nanocomposites with two main functions called barrier effect
and catalytic effect against the polymer degradation (Zhao et al. 2005). In general,
the dispersed crystalline nano- fillers behave as an insulator for heat transfer and a
barrier against the diffusion of the volatile compounds formed during thermal
decomposition. Nano-fillers increase the thermal stability of the polymer under
oxidative conditions through its oxygen barrier properties (Pavlidou and
Papaspyrides, 2008).
6.5.5 Surface Properties
The incorporation of nano-fillers into biopolymers can also affect the surface properties of the final material. The surface properties have a key role in food packaging
applications, such as printing, lamination and co-extrusion. The addition of filler
H. Cakmak and E. Sogut