5.2 Interphase Characterisation of PVA-Based Bionanocomposites
135
between nanofillers of both Cloisite 30B clays and HNTs decreases to cause particle
overlap and agglomeration when nanofiller loading increases accordingly. It is very
clearly shown in Fig. 5.14b that Cloisite 30B clay aggregates reveal typical stacks
of layered structures. On the other hand, the debonding effect takes place with the
addition of excessive amounts of Cloisite 30B clays and HNTs, Fig. 5.14c, f, respectively. Nonetheless, as seen from Fig. 5.14b, d, e, Cloisite 30B clays in large stacks of
layered structures, as well as HNTs seem to easily form large particle agglomerates
as opposed to NBCs. Such results can be associated with their relatively high aspect
ratios prone to considerable particle waviness to deteriorate their reinforcement efficiency, thus resulting in less favourable mechanical properties of corresponding PVA
nanocomposites. In addition, nanofiller dispersion methods such as ultrasonication
[18] can also give rise to possible structure damage of nanofillers with high ultrasonic
power intensity resulting in detrimental properties, as evidenced by AFM images of
Cloisite 30B clays and HNTs in corresponding Fig. 5.3a and 5.4a.
5.3 Summary
In this chapter, the following key points can be summarised:
• A pioneering approach has been developed for determining nanoelastic behaviour
of PVA nanocomposites, as well as 3D interphase dimensions and interphase
moduli in terms of surface area and interphase volume.
• Experimental characterisation results indicate that interphase thickness appears to
be nonuniform among individual particles, but becomes independent of particle
thickness.
• Interphase modulus in PVA-based nanocomposite system is enhanced with
increasing interphase volume. Moreover, interphase modulus in case of PVA/NBC
nanocomposites is higher than those for PVA/Cloisite 30B clay nanocomposites
and PVA/HNT nanocomposites with respect to V interphase /V nanofillers .
• Nanomechanical properties and sizes of interphases depend greatly on nanofiller
dispersion state. Nevertheless, increasing nanofiller content has been found to
result in the decrease in intraparticle spacing leading to particle agglomeration
with the interfacial debonding between PVA matrices and nanoparticles.
• Two key geometric parameters comprising interphase surface area and interphase
volume have been detected to be non-constant variables, which can be potentially influenced by nanofiller dimensions and sizes, as well as nanofiller dispersion states. Our approach enlightens a more effective approach to consider actual
interphase properties in theoretical and numerical modelling framework instead
of using a simple assumption of single interphase layer dimensions and uniform
interphase properties in order to achieve more accurate prediction for overall
properties of nanocomposite systems.
135
between nanofillers of both Cloisite 30B clays and HNTs decreases to cause particle
overlap and agglomeration when nanofiller loading increases accordingly. It is very
clearly shown in Fig. 5.14b that Cloisite 30B clay aggregates reveal typical stacks
of layered structures. On the other hand, the debonding effect takes place with the
addition of excessive amounts of Cloisite 30B clays and HNTs, Fig. 5.14c, f, respectively. Nonetheless, as seen from Fig. 5.14b, d, e, Cloisite 30B clays in large stacks of
layered structures, as well as HNTs seem to easily form large particle agglomerates
as opposed to NBCs. Such results can be associated with their relatively high aspect
ratios prone to considerable particle waviness to deteriorate their reinforcement efficiency, thus resulting in less favourable mechanical properties of corresponding PVA
nanocomposites. In addition, nanofiller dispersion methods such as ultrasonication
[18] can also give rise to possible structure damage of nanofillers with high ultrasonic
power intensity resulting in detrimental properties, as evidenced by AFM images of
Cloisite 30B clays and HNTs in corresponding Fig. 5.3a and 5.4a.
5.3 Summary
In this chapter, the following key points can be summarised:
• A pioneering approach has been developed for determining nanoelastic behaviour
of PVA nanocomposites, as well as 3D interphase dimensions and interphase
moduli in terms of surface area and interphase volume.
• Experimental characterisation results indicate that interphase thickness appears to
be nonuniform among individual particles, but becomes independent of particle
thickness.
• Interphase modulus in PVA-based nanocomposite system is enhanced with
increasing interphase volume. Moreover, interphase modulus in case of PVA/NBC
nanocomposites is higher than those for PVA/Cloisite 30B clay nanocomposites
and PVA/HNT nanocomposites with respect to V interphase /V nanofillers .
• Nanomechanical properties and sizes of interphases depend greatly on nanofiller
dispersion state. Nevertheless, increasing nanofiller content has been found to
result in the decrease in intraparticle spacing leading to particle agglomeration
with the interfacial debonding between PVA matrices and nanoparticles.
• Two key geometric parameters comprising interphase surface area and interphase
volume have been detected to be non-constant variables, which can be potentially influenced by nanofiller dimensions and sizes, as well as nanofiller dispersion states. Our approach enlightens a more effective approach to consider actual
interphase properties in theoretical and numerical modelling framework instead
of using a simple assumption of single interphase layer dimensions and uniform
interphase properties in order to achieve more accurate prediction for overall
properties of nanocomposite systems.