A Combined Experimental and Molecular Simulation Study of Factors Influencing the Selection of Antioxidants in Butadiene Rubber

Abstract

For the selection of antioxidants, internal factors were proposed by analyzing the thermal-oxidative aging process, which consisted of the following two inseparable steps: (1) the physical process of oxygen (O) entering the rubber network and (2) the complex chemical process of O reacting with the rubber network. Antioxidants 2246, 6PPD, and MB, examples of amines, phenols, and heterocycles, respectively, were chosen to study these factors influencing the selection of antioxidants for the thermal-oxidative aging of butadiene rubber (BR). Through thermogravimetric analysis coupled with Fourier transform infrared spectroscopy and kinetic analysis by the Flynn-Wall-Ozawa method, the dissociation reaction of BR was identified to be the rate-determining step for the thermal-oxidative aging of BR. Meanwhile, the decisive positions of the dissociation reactions for the three antioxidants in improving the thermal-oxidative stability of BR were also identified. Therefore, the internal factors were subdivided into five items (i.e., the free energy of reaction for the dissociation of antioxidant, the mole ratio of active radicals or hydroperoxides that could react with the same mass of antioxidant, the solubility and mobility of the antioxidant in BR, and the permeability of O). Combined with molecular dynamics simulations and quantum mechanics simulations, the five internal factors were clarified and quantified over the entire usable temperature range of BR. To clarify the relative importance of each factor in the selection of antioxidants, we identified the time-dependent tensile strength and elongation at break as the only responses for the first and second gray relational analyses. The relative importance of the five internal factors was evaluated and ranked in terms of gray relational grade. The two analyses were consistent and showed that, in the selection of antioxidants, we should give priority to the free energy of the dissociation reaction and the permeability of O.

Quantitative relationships between intermolecular interaction and damping parameters of irganox‐1035/NBR hybrids: A combination of experiments, molecular dynamics simulations, and linear regression analyses

“…Solubility parameter (δ) was a useful parameter to predict the compatibility of two components. Empirically, for two materials A and B , if the absolute difference of the solubility parameters (Δδ = |δ A − δ B |) is <2.05 (J/cm 3 ) 0.5 , the two components are compatible; if Δδ is between 2.05 and 6.95 (J/cm 3 ) 0.5 , they are partially compatible; if Δδ is larger than 10.02 (J/cm 3 ) 0.5 , they are incompatible . So, the δs of NBR230S and four hindered phenols (listed in Table ) were first calculated.…”

Study on the Effect of Zinc on the Rheological, Mechanical and Thermal Properties and Fire Hazard of Unfilled and Filled CR/BR Vulcanizates

“…The shear testing parameters were as follows: temperature: 25 • C, sample deformation rate: 10 rad/s, stress: from 0.1% to 150%, test force: 10 N. The Payne effect was performed for filled vulcanizates and compared with the reference sample. The Payne effect values (∆G') for composites were calculated from the Equation (7):…”

“…The participation of individual units is important for the chemical structure of BR, and thus for its functional properties [4,5]. Vulcanizates made of stereospecific BR (showing a high regularity of structure) have a low hysteresis, and thus a low coefficient of friction, high abrasion resistance and good dynamic properties [6][7][8]. Additionally, due to its low glass transition temperature (T g ~105 • C), compared to the styrene-butadiene rubber (SBR) or natural rubber (NR), this rubber is preferred, in particular, for the production of tires with low rolling resistance.…”

Bromination Modification of Butyl Rubber and Its Structure, Properties, and Application

“…The coefficients showed a decreasing trend from BIIR-1# to BIIR-3#, which suggested that the gas permeability gradually increased with the increase in the bromine content. As reported earlier, − the diffusion of small molecular gas in polymer materials is extremely sensitive to free volume. After IIR was brominated to form BIIR, a certain amount of bromine atoms was introduced into the IIR molecular chain.…”