Synergistic enhancement of mechanical, viscoelastic, transport, thermal, and radiation aging characteristics through chemically bonded interface in nanosilica reinforced EPDM‐CIIR blends

Abstract

The study investigates the influence of bis(3‐triethoxysilylpropyl)tetrasulfide (TESPT) grafted nanosilica (NS) reinforcement on the mechanical, viscoelastic, thermal, and transport characteristics as well as behavior after exposure to different cumulative γ‐radiation doses of EPDM‐CIIR blends for application in nuclear and hydrocarbon environments. The tensile strength and modulus of the nanocomposites were enhanced upto 64% and 118%, respectively whereas solvent diffusion coefficient reduced by 22%. The degradation onset temperature improved from 485°C for unfilled blends to 503°C for the nanocomposites. γ‐radiation aging resistance of EPDM‐CIIR blends improved with incorporation of nanosilica, with blends containing 7.5phrNS showing optimum properties and radiation aging resistance. The property improvements are attributed to the dispersion of NS and chemically interfaced covalent linkages between SiO2‐EPDM/CIIR chains that provides large interfacial area for effective stress transfer and creates barrier to free radical and solvent permeation. The applicability of Korsmeyer‐Peppas, Peppas‐Sahlin, and Higuchi models to predict of sorption behavior are investigated. Coats‐Redfern and Horowitz‐Metzger models were employed to evaluate the activation energy for thermal degradation. Slight decline in properties at higher nanofiller contents was due to the formation of agglomerates. TEM, FTIR, and rheological curves were utilized to corroborate these observations. FTIR and ESR analysis provided insight on the chemical changes in the nanocomposites after irradiation.

Thermal stability of gamma irradiated ethylene propylene diene monomer composites for shielding applications

“…It was clearly shown that a decrease in swelling ratio by irradiation, results in increase in crosslinking density and hence decrease in the elongation 34 . Gamma radiation induced free radicals or unpaired electrons have played key role in the fromation of crosslinks 35,39 . The strain deformation capability of EPDM composites is reduced and attributed to crosslinking which limits the ultimate chain stretch 40 .…”

“…34 Gamma radiation induced free radicals or unpaired electrons have played key role in the fromation of crosslinks. 35,39 The strain deformation capability of EPDM composites is reduced and attributed to crosslinking which limits the ultimate chain stretch. 40 There is possibility that an increase in the crosslink density give rise to saturation level of ultimate chain stretch for the EPDM composites.…”

A Systematic Investigation of the Kinetic Models Applied to the Transport Behaviors of Aromatic Solvents in Unfilled Hydrogenated Nitrile Rubber/Ethylene Propylene Diene Monomer Composites

“…It should be noted that the phenomenon K f >> K r occurred in most research work about rubber-solvent systems [15][16][17]. In particular, in the study of cyclohexane in nanosilica-reinforced ethylene propylene diene monomer/isobutylene isoprene rubber, Neelesh Ashok found that the K f values were much lower than the K r values, and the n values were always higher than 1.0 [18]. However, all the above work for rubber-solvent systems did not elaborate on or limit the transport time or degree of solvent used for mathematical fitting, which were different from the 60% degree of drug release [19].…”

Thermal Stability and Non-Isothermal Kinetic Analysis of Ethylene–Propylene–Diene Rubber Composite

“…Neelesh Ashok et al [18] investigated the mechanical, viscoelastic, thermal, and transport properties of EPDM-CIIR blends reinforced with bis(3-triethoxysilylpropyl)tetrasulfide (TESPT)-grafted nano-silica after exposure to different cumulative radiation doses. The nanocomposites had a degradation onset temperature of 503 • C, compared to 485 • C for unfilled blends.…”