INFLUENCE OF ADDITIONAL INHIBITORS ON CATALYTIC DESTRUCTION REACTION OF POLYISOBUTYLENE
Authors: Fatimə Novruzova Fatimə Novruzova , Khuraman Hajiakhmedzade Khuraman Hajiakhmedzade , Esfira Bagirova Esfira Bagirova , Irina Akhmedova Irina Akhmedova 
Published: January 2022

It is impossible to create a scientific basis for the synthesis of polymers without taking into account the destruction process. Under the action of Lewis acids, the destruction of PIB follows a free radical chain mechanism, while the catalytic destruction of PIB leads to the formation of both linear and branched macromolecules.
The most wide-spread type of chemical destruction is an oxidative destruction by oxygen and ozone. The oxidative destruction is activated by heat, light rays and mechanical energy, and the types of thermal, photo and mechanical oxidative destruction are known, respectively. As a result of these destructive reactions, both the composition and the structure of polymer change, that is, it “grows old”. The aging of a polymer means a change in its physical-chemical, physical-mechanical properties during exploitation . The fastest oxidative destruction of polymers occurs by a chain mechanism (with free radicals), as in low molecular weight hydrocarbons. The oxidation process of polymers without double bonds in the chains proceeds weakly, and the formation of peroxide groups is not always observed in them. This process consists of three stages: formation of an active center, lengthening and breaking of the chain. It is known that oxidation begins with the formation of peroxides. Active centers are obtained by the decomposition of peroxides.
When studying the chemistry of the reaction, it was noticed that there is another mechanism for the destruction of polyisobutylene in the presence of strong Lewis acids, characteristic of cationic processes.
One of the interesting aspects of the destruction process is a complete understanding of the "chemistry" of catalytic destruction. For this, various additives must be added to the catalytic reaction.
During the experiments it has been found that the reaction does not take place in a completely dried solvent. The reaction proceeds when a significant amount of water is added to the system. The amount of water in the system is [H2O] ≈10-3 mol / l. This can be explained by the fact that the catalyst in dimer form is inactive in the nonpolar helix, but the water plays the role of a polar additive, decomposing the dimer catalyst and converting it into the monomeric form of Brønsted acid.
Therefore, the inhibitory effect of 2,6-DTBP and toluene on the reaction has been studied in order to fully elucidate the chemistry of the catalytic destruction of PIB by Lewis acids. Since 2,6-DTBP is a trap for protons, it plays an important role in the detection of the active form of the catalyst. The ineffectiveness of 2,6-DTBP and toluene as an inhibitor led to the existence of a radical reaction mechanism and the discovery of the active form of the catalyst. For better understanding the reaction mechanism, the inhibitory effect of O2, p-benzoquinone and tetracyanethylene on the reverse process has been studied.
The formation of block copolymers upon modification of PIB with acrylonitrile and vinyl acetate, polymerized by the radical mechanism, not only confirms the radical mechanism of destruction, but also creates conditions for the production of new copolymers. The formation of active centers has been also confirmed by the EPR method, free macroradicals have been detected and their density has been determined. The formation of free macroradicals as a result of the direct action of strong mechanical energy, direct mechanical cracking or transfer of vibration energy of the initial highly active state of the polymer chain is the initial stage of mechanical and chemical processes. The overall final result of the transformations depends on the direction of the subsequent secondary reactions of free macroradicals. Although these reactions are different, they correspond to typical free radical processes in polymer systems.
On the whole, destructive reactions are considered one of the most important reactions for high molecular weight compounds. They are used to study the structure of high molecular weight compounds, as well as to obtain low molecular weight compounds from the natural polymers.
All this has been reflected in IR, UV, NMR, EPR spectroscopic studies. A mathematical and kinetic model of the processes has been developed and parameters have been calculated using the experimental indicators of the carried out researches.
Keywords: catalyst, 2,6-DTBP, toluene, polyisobutylene, destruction, halide, aikyl halide, inhibitor, deactivation, methano