Nanocomposites and nanomaterials

Features of PHTFE – SnO2 polymer nanocomposites 
heat conductivity
M.O. Rokytskyi, M.I. Shut, T.G. Sichkar, H.V. Rokytska, A.M. Shut
Faculty of Physics and Mathematics, National Pedagogical Dragomanov University, Ministry of Education and Science of Ukraine. Pirogova Str., 9, Kyiv-01601, Ukraine.
E-mail: maksalrokitskiy@gmail.com

Due to its unique physicochemical properties and considerable application potential, the study of polymer nanocomposites is an urgent task. Among such nanocomposites, high potentials for the creation of materials with high protective and absorbent properties with specified electro- and thermophysical properties and low content of nanodispersed fillers have polymer nanocomposites of polychlorotrifluoroethylene (PCTFE) - SnO2 tin dioxide.
Samples for the heat conductivity studies were prepared as follows: a mixture of PCTFE with a particle size of 200 nm in the form close to spherical and SnO2 with a particle size of 40 ÷ 150 nm homogenized in a liquid acoustic medium and after heat treatment in a vacuum cabinet was pressed from the polymer melt under the same thermal conditions (T =513 K, p = 32 MPa), which corresponds to the technological conditions of processing PCTFE into products at volume concentrations of SnO2 0 ÷ 54 % (vol.).
Studies of the temperature dependences of heat conductivity in the temperature range 313 ÷ 503 K were carried out with continuous change of the heater temperature in modes close to regular heating using a dynamic λ-calorimeter, which is a modernized heat conductor meter “ИT-λ-400”. The temperature and concentration dependences of the thermal conductivity coefficient (λ) obtained from the studies show that, in general, the concentration dependence of λ can be divided into 3 zones. The first zone (0 ÷ 3 %) corresponds to a slight change in thermal conductivity, passes into the second zone (3 ÷ 10 %), which corresponds to the achievement on the development of the percolation threshold, accompanied by a marked increase in λ (0,13 ÷ 20 W/(m.K) and moves into the third zone (10 ÷ 54 %), where the value of λ continues to grow, but much slower than in the second zone. Such features of the heat conductivity can be caused by transition of a part of polymer to the state of interfacial layer at the interface of the polymer - oxide nanofiller. It should be noticed, that even at low concentrations of the filler, major changes in the composite occur due to changes in the structure of the polymer in the interfacial and wall to the particles of the filler layers.