Inhibition of Free Radical Polymerization: A Review

Abstract

Polymerization reactions have caused several severe accidents in the past since they are prone to runaways due to their highly exothermic and auto-accelerating nature. The heat generated during these uncontrolled runaway reactions surpasses the heat removal capacity of the cooling system leading to the auto-acceleration of the reactions. If proper measures are not taken to attenuate this auto-accelerative nature, dangerous consequences ensue, such as rampant boiling of the reaction system fluids or vapor production from secondary reactions. Both these consequences may eventually lead to over-pressurization followed by a thermal explosion. Thus, to eliminate the associated risk, polymerization reactions in industries are carried out in the presence of inhibitors which are injected into the reaction system before the initiation of polymerization. In this review, I have summarized various accidents that have happened in the past due to runaway polymerization implicating that there is an urgent necessity to do further research in this relatively less explored field of polymerization inhibition. To this end, I have completed an exhaustive survey of the various types of inhibitors used in industries and their inhibition mechanisms focusing mainly on the auto-initiated polymerization of styrene, methyl methacrylate, and acrylic acid monomer. Lastly, the synergism in the inhibition performance of a mixture of two types of inhibitors was also compared and discussed in detail.

Chemical Method Based on Thermally Activated Free Radical Polymerization to Determine the Temperature in Thermoplasmonics

“…Furthermore, to account for the difference between both approaches, the exothermic property of the free radical polymerization of acrylate monomer can be considered . Indeed, as radical polymerization reactions are known to be highly exothermic, , it seemed necessary to take this parameter into account and calculate the temperature generated by this process. The temperature difference generated by the polymerization reaction is given by normalΔ T = normalΔ H m C normalp where Δ H is the enthalpy of the reaction, m is the mass of the system (here, the mass of the formulation) and C p is the mass heat capacity of the formulation.…”

Superabsorbent Hydrogels in the Agriculture and Reclamation of Degraded Areas

“…MEHQ oxidation reactions using a thermal initiator such as persulphate are responsible for the colour of the finished product [86]. Monomer producers may also add other substances that stabilize free radicals (polymerisation inhibitors), such as phenothiazine (0.1%) [87,88], hydroquinone monomethyl ether (0.1%) [87], methylene blue (0.5-1%) and N,N′-diphenyl-p-phenylenediamine O HO CH 3 Monomer producers may also add other substances that stabilize free radicals (polymerisation inhibitors), such as phenothiazine (0.1%) [87,88], hydroquinone monomethyl ether (0.1%) [87], methylene blue (0.5-1%) and N,N ′ -diphenyl-p-phenylenediamine (0.05%) [89]. Stabilisers and oxygen dissolved in the acrylic acid prevent polymerisation during transport and storage, but in their presence, unfavourable non-radical processes occur [89,90].…”

“…Sustainability 2024, 16, x FOR PEER REVIEW 6 of 29 (0.05%) [89]. Stabilisers and oxygen dissolved in the acrylic acid prevent polymerisation during transport and storage, but in their presence, unfavourable non-radical processes occur [89,90]. One such transformation is the acid dimerisation reaction.…”

"Jute Fiber Grafted with MMA and MA to Improve its Physical and Dyeing Characteristics"

“…This variation may be due to the chemical features and the presence of double bonds in vinyl monomers bestows polyfunctionality on them. In addition, MMA is more chemically reactive than that MA due to their substituent structure, which increases the reactivity of a monomer towards radical attack [13,22]. As a result, maximum graft yield and grafting efficiencies are in favour of MMA.…”