Radiation effect on properties of carbon black filled NBR/EPDM rubber blends

Mechanical Properties, Radiation Resistance Performances, and Mechanism Insights of Nitrile Butadiene Rubber Irradiated with High-Dose Gamma Rays

The radiation effect of materials is very important and directly related to the safety and reliability of nuclear reactors. Polymer materials, one of the indispensable materials in nuclear power equipment, must withstand the ordeal of high-energy ionizing rays. In this work, through screening different γ-ray dose irradiation conditions, we systematically and comprehensively study the changes in the structure and properties of nitrile butadiene rubber (NBR) before and after γ-ray static irradiation at a high dose rate, and master the rule and mechanism of the γ-ray static irradiation effect of these polymer materials. The mapping relationship between the macroscopic properties, microstructure, and irradiation dose of NBR is accurately characterized. With an increase in total irradiation dose, the C=C double bond reaction occurs, and the C≡N bond, C=C, and C=O participate in the hyper crosslinking reaction. The glass transition temperature (Tg) increases with the cumulative irradiation amount. With the increased total irradiation amount, the degree of rubber cross-linking increases, causing an increased crystallinity and decomposition temperature. A growing amount of gamma irradiation causes the mechanical properties of the rubber to degrade simultaneously, increasing the shore hardness while decreasing the tensile strength and ultimate elongation at break. When the cumulative amount reaches 1 MGy, the ultimate elongation at break decreases significantly. A cumulative dose of radiation resistance of 4 MGy can be achieved by the samples. This work can provide theoretical and experimental support for the long-term stability of nitrile butadiene rubber and its derivatives in nuclear radiation fields and space radiation conditions.

The Contribution of BaTiO3 to the Stability Improvement of Ethylene-Propylene-Diene Rubber: Part I-Pristine Filler

This study presents the functional effects of BaTiO₃ powder loaded in ethylene-propylene-diene rubber (EPDM) in three concentrations: 0, 1, and 2.5 phr. The characterization of mechanical properties, oxidation strength, and biological vulnerability is achieved on these materials subjected to an accelerated degradation stimulated by their γ-irradiation at 50 and 100 kGy. The thermal performances of these materials are improved when the content of filler becomes higher. The results obtained by chemiluminescence, FTIR-ATR, and mechanical testing indicate that the loading of 2.5 phr is the most proper composition that resists for a long time after it is γ-irradiated at a high dose. If the oxidation starts at 176 °C in the pristine polymer, it becomes significant at 188 and 210 °C in the case of composites containing 1 and 2.5 phr of filler, respectively. The radiation treatment induces a significant stability improvement measured by the enlargement of temperature range by more than 1.5 times, which explains the durability growth for the radiation-processed studied composites. The extension of the stability period is also based on the interaction between degrading polymer substrate and particle surface in the composite richest in titanate fraction when the exposure is 100 kGy was analyzed. The mechanical testing as well as the FTIR investigation clearly delimits the positive effects of carbon black on the functionality of EPDM/BaTiO₃ composites. The contribution of carbon black is a defining feature of the studied composites based on the nucleation of the host matrix by which the polymer properties are effectively ameliorated.

Effects of Filler Functionalization on Filler-Embedded Natural Rubber/Ethylene-Propylene-Diene Monomer Composites

Natural rubber (NR) presents a number of advantages over other types of rubber but has poor resistance to chemicals and aging. The incorporation of ethylene propylene diene monomer (EPDM) into the NR matrix may be able to address this issue. Mineral fillers, such as carbon black (CB) and silica are routinely incorporated into various elastomers owing to their low cost, enhanced processability, good functionality, and high resistance to chemicals and aging. Other fillers have been examined as potential alternatives to CB and silica. In this study, phlogopite was surface-modified using 10 phr of compatibilizers, such as aminopropyltriethoxysilane (A1S), aminoethylaminopropyltrimethoxysilane (A2S), or 3-glycidoxypropyltrimethoxysilane (ES), and mixed with NR/EPDM blends. The effects of untreated and surface-treated phlogopite on the mechanical properties of the rubber blend were then compared with those of common fillers (CB and silica) for rubbers. The incorporation of surface-modified phlogopite into NR/EPDM considerably enhanced various properties. The functionalization of the phlogopite surface using silane-based matters (amino- and epoxide-functionalized) led to excellent compatibility between the rubber matrix and phlogopite, thereby improving diverse properties of the elastomeric composites, with effects analogous to those of CB. The tensile strength and elongation at break of the phlogopite-embedded NR/EPDM composite were lower than those of the CB-incorporated NR/EPDM composite by 30% and 10%, respectively. Among the prepared samples, the ES-functionalized phlogopite showed the best compatibility with the rubber matrix, exhibiting a tensile strength and modulus of composites that were 35% and 18% higher, respectively, compared with those of the untreated phlogopite-incorporated NR/EPDM composite. The ES-functionalized phlogopite/NR/EPDM showed similar strength and higher modulus (by 18%) to the CB/NR/EPDM rubber composite, despite slightly lower elongation at break and toughness. The results of rebound resilience and compression set tests indicated that the elasticity of the surface-modified phlogopite/NR/EPDM rubber composite was higher than that of the silica- and CB-reinforced composites. These improvements could be attributed to enhancements in the physical and chemical interactions among the rubber matrix, stearic acid, and functionalized (compatibilized) phlogopite. Therefore, the functionalized phlogopite can be utilized in a wide range of applications for rubber compounding.

Effect of nanofiller on the ageing of rubber seal materials under gamma irradiation

The effect of high gamma irradiation and nanosilica on the structure and mechanical properties of the acrylonitrile butadiene rubber seal materials was investigated in this study. Acrylonitrile butadiene rubber nanocomposites containing (25, 50 and 75 phr) unmodified and modified nanosilica were irradiated at different doses (0, 0.2, 0.4, 0.6, 0.8, 1 MGy). The dispersion of nanosilica-based filler in acrylonitrile butadiene rubber was investigated by scanning electron microscope. Fourier-transform infrared analysis, swelling, crosslinking, mechanical and the thermal resistance properties of acrylonitrile butadiene rubber nanocomposites were investigated. From the results, it is clear that with modified nanosilica, acrylonitrile butadiene rubber phase crosslinking is accelerated with increasing γ-doses compared to unmodified nanosilica and seems to enhance physical, mechanical and the thermal properties of the rubber. The surface of the acrylonitrile butadiene rubber nanocomposites was investigated by scanning electron microscope and found better dispersion for acrylonitrile butadiene rubber with 25 phr of modified nanosilica at 0.6 MGy. The compression set of the results indicated that 25 phr modified nanosilica has best properties under high gamma irradiation.

Synergistic effect of vermiculite clay and ionizing irradiation on the physical and mechanical properties of polybutadiene rubber/ethylene propylene diene monomer nanocomposite

Blends of rubber-rubber have desired properties intermediated between two rubber matrices. On the other hand, polymer-clay nanocomposites have attracted the attention of many researchers and experimental results are presented in a large number of recent papers and patents because of the outstanding mechanical properties and low gas permeability that are achieved in many cases. Polymer-clay nanocomposites are a new class of mineral-field polymer that contain relatively small amounts (<10%) of nanometer-sized clay particles. In this study, new nanocomposite materials were produced from the blend of polybutadiene rubber (BR) and ethylene propylene diene monomer rubber (EPDM), BR/EPDM (50/50) as matrix and organically modified vermiculite clay (VMT) by quaternary alkylammonium in different contents (3, 6, 9 and 12 phr) as the filler by using rubber mill then, the rubber nanocomposite sheets were irradiated at doses of 25, 50, 75, 100 and 150 kGy using γ-radiation technique as a crosslinking tool. The prepared composites can be characterized by using various analytical techniques including X-ray diffractometer (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) as well as mechanical properties measurements.