A COMPARATIVE ANALYSIS OF THE CONTENTS OF INTERFACIAL REGIONS AND THEIR INFLUENCE ON THE PROPERTIES OF NANOCOMPOSITES POLYMER/CARBON NANOTUBES
Nowadays, the significance of interfacial regions in the formation of polymer nanocomposites properties is internationally recognized. Structurally, these regions can be considered from two points of view: as regions, whose packing density is higher than the corresponding characteristic for bulk polymer matrix, and as a reinforcing element of nanocomposite structure, whose elasticity modulus is considerably higher than the modulus of the indicated polymeric matrix. This paper presents the results of the comparison of relative fractions of interfacial regions, obtained within the framework of the two above mentioned approaches. To determine the indicated parameter, the angular tangent of mechanical loss is used in the the first approach whereas the second approach uses the reinforcement degree of nanocompositespolydicyclopentadiene/carbon nanotubes with an elastomeric polymeric matrix. Both methods of calculation of relative fraction of interfacial regions demonstrated good correspondence. This circumstance indicates the equivalence of notions of densely-packed (crystallizing) and high-modulus (reinforcing) interfacial regions. This postulate was confirmed by the calculation of the reinforcement degree of the considered nanocomposites within the framework of percolative model of reinforcement, where the reinforcing element of nanocomposites structure is the total relative fraction of nanofiller (carbon nanotubes) and interfacial regions. The reinforcement degree calculated by the indicated method shows good correspondence with the experimental results. In conclusion, let us consider two important methodological aspects. Firstly, the ordered (or crystallizing) regions of polymeric matrix, not included in interfacial regions, do not serve as a reinforcing element of the nanocomposite structure. This means that the determination of the relative fraction of interfacial regions within the framework of the percolative model of reinforcement does not take into consideration the level of local order of the bulk polymeric matrix. Secondly, precise calculation of carbon nanotube density is required to estimate their volumetric content. Using traditional values of the parameter for this purpose leads to artificially lowered values of nanocomposites characteristics.