Authors:A. Ponomarenko, C. Klason, N. Kazantseva, M. Buzin, M. Alexandre, Ph. Dubois, I. Tchmutin, V. Shevchenko, and R. Jérôme
Thermogravimetry was used to investigate the effects of different inorganic functional fillers on the heat resistance of polymer
matrices. The kinetic parameters of thermal oxidative degradation were shown to depend on the polymer, the chemical composition
of the filler surface, the filler concentration, and the processing method, which determines the distribution of filler particles
in the polymer matrix. Magnetic fillers (carbonyl iron, and hexaferrites of different structural types) were shown to be chemically
active fillers, increasing the heat resistance of siliconorganic polymers. Their stabilizing effect is due to blocking of
the end silanol groups and macroradicals by the surface of the filler and non-chain inhibition of thermal oxidative degradation.
In the case of fiber-forming polymers (UHMWPE, PVOH and PAN), most magnetic fillers are chemically inert, but at concentrations
of 30–50 vol% they increase the heat resistance of the composite. Addition of carbon black increased the heat resistance of
the thermoplastic matrix. The dependence of the thermal degradation onset temperature on the kaolin concentration in the polyolefin
matrix exhibited a maximum. Analysis of the experimental results demonstrated the operating temperature ranges for different
composites, and their maximum operating temperature.
Authors:B. Lebedev, T. Kulagina, M. Ryabkov, S. Ponomarenko, E. Makeev, N. Boikov, V. Shibaev, E. Rebrov, and A. Muzafarov
The thermodynamic properties of carbosilane dendrimer of second generation with terminal methoxyundecylene groups were studied
between 6 and 340 K by adiabatic vacuum calorimetry: the temperature dependence of the molar heat capacity Cp0 was measured, the physical transformations were established and their thermodynamic characteristics were obtained. The experimental
data were used to calculate the thermodynamic functions Cp0 (T), H0(T)-H0(0), S0(T), G0(T)-H0(0) of the compound in the range 0 to 340 K. from the relation Cp0 (T) the fractal dimension of the dendrimer was experimentally determined. The heat capacity of the dendrimer was compared with
the corresponding additive values calculated from the properties of its constituents - a dendritic matrix (carbosilane dendrimer
of second generation) and the corresponding amount of moles of methyl ester of 11-(tetramethyldisiloxy)undecanoic acid serving
as terminal groups.