EXPERIMENTAL SUBSTANTIATION OF THE ANTIOXIDATIVE EFFECT OF COMPLEX CARBON-SILICON COMPOSITE BASED ON CARBONIZED RICE HUSK AND STRAW

In modern polymer materials science, special attention is paid to the rational use of renewable raw materials, in particular plant waste. A new complex carbon-silicon composite (carbon-silicon filler, (CSF)) obtained by carbonization of rice husk and straw at a temperature of 550-600 ℃ has proven itself in rubbers as an effective partial replacement for technical carbon. When it is introduced into polyethylene, a significant inhibition of the processes of thermo-oxidative aging of the polymer is observed, previously estimated both by a change in the deformation-strength properties of the material and by a decrease in the thermal effect of the oxidation process (differential scanning calorimetry) and an increase in the temperature of the onset of mass loss (thermogravimetric analysis) relative to a number of comparison objects. To identify the causes of the observed effect, the chemical composition of CSF was studied. Thermogravimetric analysis showed the presence of bound water in the composition of CSF up to 3% by weight and an organic component, also up to 3% by weight. Using the method of IR spectroscopy of the ATR and transmission IR spectroscopy it was established that the composition of CSF contains aliphatic methylene groups, monoaromatic and polycyclic hydrocarbons, including substituted ones, as well as phenols linked by intermolecular hydrogen bonds. Thus, the studied composite contains structures characteristic of effective stabilizers of polyolefins - phenolic antioxidants, which obviously provides the antioxidant action of CSF. The antioxidant action of the complex composite from rice waste is additionally confirmed by a decrease in the thermal effect of the oxidation process when filling HDPE, as well as by the fact that the optical density of the carbonyl group bands of the filled LDPE subjected to thermal oxidation is 1.9 times lower than that of the oxidized LDPE that does not contain CSF. The use of inexpensive filler from renewable plant raw materials, which are agricultural waste, will not only expand the range of multifunctional fillers for polymers, but also reduce the cost of polymer materials and reduce the environmental impact.