Radical bulk polymerization of styrene in the presence of rubber particles from recycled tires: a kinetic study using DSC

Abstract

The kinetic developments of the free-radical bulk polymerization of styrene in the presence of recycled rubber tire particles are studied by isothermal differential scanning calorimetry (DSC). Two different chemical initiators, namely benzoyl peroxide (BPO) and 2,2'-Azobis(2methylbutyronitrile) (AMBN), are tested in a series of variable-composition experiments, under three different polymerization temperatures, in order to selectively address the role of the different species on the evolution of the polymerization reaction. The variation of the overall effective kinetic rate constant and activation energy of the polymerization are also calculated to quantify the effect of the addition of the particulate filler. The results of the study demonstrate that the combination of the peroxide initiator agent with a composition of the reacting mixture in the order of 30 mass%, in terms of the rubber tire particles, results in a significant deviation of the evolution of the rate of polymerization and monomer conversion, with respect to that of the pure homopolymerization system in the absence of tire particles. The observed phenomena are consistent with previous studies reported in the literature and are mainly attributed to the chemical interactions taking place between the initiator agent and additives of the formulation of the tire particles.

A Comprehensive Study on the Styrene–GTR Radical Graft Polymerization: Combination of an Experimental Approach, on Different Scales, with Machine Learning Modeling

“…This work builds on previously reported results of an ongoing study on the styrene-GTR radical graft polymerization system [27][28][29]. More specifically, a part of this ongoing study has already focused on the modeling of the system via the introduction of a generalized kinetic scheme that has been employed to describe the evolution of the polymerization in the presence of different amounts of GTR and/or benzoyl peroxide (BPO) initiator, under different reaction temperatures [29].…”

“…GTR particles were obtained from DeltaGom France and used without further purification as well. The characteristics of GTR have been discussed elsewhere [27,28]. Even if the presence of stabilizers and impurities can greatly affect polymerization kinetics, these were not removed within the perspective of implementing this process at a larger scale.…”

“…This limits the mastery of the process and reduces the capacity of a detailed modeling of the system to better understand the link between the process parameters (e.g., temperature/time of the reaction and initial compositions of reactants) and the final productivity and product quality indicators (e.g., styrene conversion rate and grafting efficiency). For example, a previous work demonstrated that additives and moieties found in varying compositions in GTR, such as carbon black, display a significant effect on the course of the polymerization [27]. Nevertheless, developing a model capable of handling this inherent system complexity and predicting the effects of the process conditions on the desired indicators of the produced GTR-based composite would be extremely beneficial to the associated recycling and circular economy sectors.…”

“…Accordingly, this work presents the implementation of a data-driven modeling approach, on the basis of supervised ML techniques, under varying operating conditions. The developed ML models are implemented as standalone regression models, for the prediction of the monomer conversion developments in an attempt to assess their suitability in modeling this highly complex polymerization system, without using any prior knowledge or mechanistic description of the underlying phenomena, as it is the case in previous works [27][28][29]. As a perspective for future work, the findings of this work will be used in the development of a hybrid modeling approach where both phenomenological and ML models of the system will be combined.…”

Reinforcing and plasticizing effects of reclaimed rubber on the vulcanization and properties of natural rubber

“…3,4 The reutilization of waste tires by means of energy and material recovery seems to be particularly important. 5 The potential of ground tire rubber (GTR) from waste tire has been explored in different fields for its excellent elasticity and aging resistance, 6 such as blending with raw rubber, 7 plastics [8][9][10][11] asphalt, 12,13 and cement, 14,15 among which the addition of GTR into raw rubber is most studied due to their similar structure. However, the covalently crosslinked polymer networks of rubber do not favor interfacial interactions between GTR and rubber matrix, leading to the generation of stress concentration points in composites and decrease their mechanical properties, which limits the application of GTR in rubber products.…”