Estimating the influence of polyorganosiloxanes on the properties of fire-retardant halogen-free polymer compositions for cable articles

The object of this study is the processes of supramolecular structure formation and the thermophysical, rheological, physical-mechanical, and electrophysical properties of halogen-free fire-resistant polymer compositions. Aluminum oxide trihydrate is used as a flame retardant. The effect of the flame-retardant filler becomes noticeable only with a significant filling (60%), when the rheological and operational properties of polymer compositions deteriorate. The use of polyorganosiloxanes makes it possible to reduce the negative impact of the filler on the thermophysical, rheological, physical-mechanical, and electrophysical properties. Therefore, the effective use of polyorganosiloxanes to regulate the properties of fire-resistant polymer compositions is an urgent task under consideration. Fire retardant halogen-free polymer compositions were studied. The content of the flame-retardant filler is 60%. The samples under study additionally contain polyorganosiloxanes, which were used as modifiers for the directed regulation of properties of fire retardant compositions. The effect of polyorganosiloxanes on the formation of the supramolecular structure of filled polymer compositions for cable articles has been established. Due to this, the phase transition temperatures increase by 2–4°C, the temperature of the beginning of decomposition by 12–17°C and the end of decomposition by 5–6°C. The effect of the influence of polyorganosiloxanes with a viscosity of 50–500 Pa·s on a decrease in the melt viscosity of fire retardant polymer compositions from 5.342 to 4.330 Pa·s with an increase in the shear rate from 20 to 60 s-1 has been shown. The results make it possible to use polyorganosiloxanes for targeted regulation of rheological and operational characteristics of fire-resistant polymer compositions for the manufacture of insulation and sheath of power cables