POLYMERS AS NATURAL COMPOSITES: STRUCTURE AND PROPERTIES - Fractal Mechanics of Polymers - page 301

nano-microworld objects (let us remind, that the condition B λ = 2.61 is valid
even in the case of earthquakes [14]). It is interesting to note, that B λ change
occurs at glass transition temperature of loosely packed matrix, that is, ap-
proximately at T g - 50 K [11].
Hence, the stated above results demonstrated that the nanocluster pos-
sessed all nanoparticles properties, that is, they belonged to substance inter-
mediate state-nanoworld.
And in completion of the present section let us note one more important
feature of natural nanocomposites structure. In Refs. [24, 25] the interfacial
regions absence in amorphous glassy polymers, treated as natural nanocom-
posites, was shown. This means, that such nanocomposites structure repre-
sents a nanofiller (nanoclusters), immersed in matrix (loosely packed matrix
of amorphous polymer structure), that is, unlike polymer nanocomposites
with inorganic nanofiller (artificial nanocomposites) they have only two
structural components.

15.3 THE NATURAL NANOCOMPOSITES REINFORCEMENT

As it is well-known [26], very often a filler introduction in polymer matrix is
carried out for the last stiffness enhancement. Therefore, the reinforcement
degree of polymer composites, defined as a composite and matrix polymer
elasticity moduli ratio, is one of their most important characteristics.
At amorphous glassy polymers as natural nanocomposites treatment
the estimation of filling degree or nanoclusters relative fraction j cl has an
important significance. Therefore, the authors of Ref. [27] carried out the
comparison of the indicated parameter estimation different methods, one
of which is EPR-spectroscopy (the method of spin probes). The indicated
method allows to study amorphous polymer structural heterogeneity, using
radicals distribution character. As it is known [28], the method, based on the
parameter d 1 / d c - the ratio of spectrum extreme components total intensity to
central component intensity-measurement is the simplest and most suitable
method of nitroxyl radicals local concentrations determination. The value of
dipole-dipole interaction ∆ H dd is directly proportional to spin probes concen-
tration C w [29]:

∆ H dd = A ⋅ C w , (15.5)

where A = 5×10 -20 Ersted⋅cm 3 in the case of radicals chaotic distribution.