24
1 Introduction to PVA-Based Bionanocomposite Films
Fig. 1.16 Schematic diagram illustrating the reinforcement mechanism in a composite material:
a before loading and b after loading [142]
become mechanically constrained, as illustrated in Fig. 1.16. This mechanism enables
nanofillers to carry a disproportionately high fraction of an applied load provided
that the interfacial bonding between polymer matrices and fillers remains sufficient.
Furthermore, it can be postulated that much greater reinforcement effect can be
achieved by using fillers with large specific surface areas. In a polymer/layered
silicate nanocomposite system, Young’s modulus can increase significantly with
the inclusion of OMLS into continuous polymer matrices, For example, Young’s
modulus increased from 1.9 GPa for neat PVA to 3.2 GPa for PVA/5 wt% MMT
nanocomposites [166]. In a similar manner, the other study reported an increase
from 1.78 GPa for neat PVA to 2.65 GPa for PVA/4 wt% MMT nanocomposites
[167].
As can be clearly seen in Table 1.3, Young’s modulus of nanocomposites is a
function of clay content. However, any further increase in the clay content appears to
make a declining effect on Young’s modulus. Based on XRD and TEM observations,
this trend is attributed to the change of clay dispersion states from full exfoliation, a
mix of exfoliation and intercalation to clay agglomeration at the clay content of 10
wt% or above [142, 143].
Apart from the change in Young’s modulus, the incorporation of organoclays into
polymer matrices also causes the increase in tensile strength of nanocomposites.
Wang et al. [166] reported that the tensile strength of PVA nanocomposites was
increased by 52% at the MMT loading of 3 wt% as opposed to that of neat polymer.
Similarly, another investigation [168] reported that the tensile strength increased
from 50 MPa for neat PVA to 95.9 MPa for PVA-based nanocomposites at the clay
loading of 17.3 wt%. Nonetheless, it should be clearly stated that the reduction in
tensile strength for nanocomposites has also been noted, Table 1.3. This result can be
1 Introduction to PVA-Based Bionanocomposite Films
Fig. 1.16 Schematic diagram illustrating the reinforcement mechanism in a composite material:
a before loading and b after loading [142]
become mechanically constrained, as illustrated in Fig. 1.16. This mechanism enables
nanofillers to carry a disproportionately high fraction of an applied load provided
that the interfacial bonding between polymer matrices and fillers remains sufficient.
Furthermore, it can be postulated that much greater reinforcement effect can be
achieved by using fillers with large specific surface areas. In a polymer/layered
silicate nanocomposite system, Young’s modulus can increase significantly with
the inclusion of OMLS into continuous polymer matrices, For example, Young’s
modulus increased from 1.9 GPa for neat PVA to 3.2 GPa for PVA/5 wt% MMT
nanocomposites [166]. In a similar manner, the other study reported an increase
from 1.78 GPa for neat PVA to 2.65 GPa for PVA/4 wt% MMT nanocomposites
[167].
As can be clearly seen in Table 1.3, Young’s modulus of nanocomposites is a
function of clay content. However, any further increase in the clay content appears to
make a declining effect on Young’s modulus. Based on XRD and TEM observations,
this trend is attributed to the change of clay dispersion states from full exfoliation, a
mix of exfoliation and intercalation to clay agglomeration at the clay content of 10
wt% or above [142, 143].
Apart from the change in Young’s modulus, the incorporation of organoclays into
polymer matrices also causes the increase in tensile strength of nanocomposites.
Wang et al. [166] reported that the tensile strength of PVA nanocomposites was
increased by 52% at the MMT loading of 3 wt% as opposed to that of neat polymer.
Similarly, another investigation [168] reported that the tensile strength increased
from 50 MPa for neat PVA to 95.9 MPa for PVA-based nanocomposites at the clay
loading of 17.3 wt%. Nonetheless, it should be clearly stated that the reduction in
tensile strength for nanocomposites has also been noted, Table 1.3. This result can be