POLYMERS AS NATURAL COMPOSITES: STRUCTURE AND PROPERTIES - Fractal Mechanics of Polymers - page 326

FIGURE 15.27 The dependences of reinforcement degree E n / E m and E p / E l.m. on the contents
of nanofiller φ n and nanoclusters φ cl , accordingly. 1÷3 - theoretical dependences ( E n / E m ) (φ n ),
corresponding to the Eqs. (15.15)÷(15.17); 4.5 - the experimental data ( E p / E l.m. ) for Par at T
= T g ' ÷ T g (4) and T < T ′ (5); 6, 7 - the experimental data ( E n / E m ) (φ n ) for EP/MMT at T > T g
(6) and T < T g (7) [59].
To obtain the similar comparison for natural nanocomposite (polymer) is
impossible, since at T ≥ T g nanoclusters are disintegrated and polymer ceases
to be quasi-two-phase system [5]. However, within the frameworks of two-
stage glass transition concept [11] it has been shown, that at temperature T ′
, which is approximately equal to T g - 50 K, instable (small) nanoclusters
decay occurs, that results to loosely packed matrix devitrification at the indi-
cated temperature [5]. Thus, within the range of temperature T ′ ÷ T g natural
nanocomposite (polymer) is an analog of nanocomposite with glassy matrix
[58]. As one can see, for the temperatures within the range of T = T ′ ÷ T g (φ cl
= 0.06÷0.19) the value E p / E l.m. corresponds to the Eq. (15.15), that is, perfect
adhesion nanoclusters-loosely packed matrix and at T < T ′ (φ cl > 0.24) - to
the Eq. (15.16), that is, to zero adhesional strength at a large friction co-
efficient. Hence, the data of Fig. 15.27 demonstrated clearly the complete
similarity, both qualitative and quantitative, of natural (Par) and artificial
(EP/MMT) nanocomposites reinforcement degree behavior. Another micro-
composite model (e.g., accounting for the layered silicate particles strong
anisotropy) application can change the picture quantitatively only. The data
of Fig. 15.27 qualitatively give the correspondence of reinforcement degree
of nanocomposites indicated classes at the identical initial conditions.