Mechanism of electrical conductivity (σ), mechanical properties, and γ‐ray transmission properties of ethylene propylene diene monomer (EPDM)/butadiene rubber (BR) composites have been investigated from the viewpoint of free volume (ie, open hole size). The EPDM/BR composites (100/0, 70/30, 50/50, 30/70, and 0/100) loaded with 50 phr carbon black as a reinforcing filler and irradiated with different doses (10, 30, 50, 70, and 100 kGy). The ortho‐positronium lifetime (o‐Ps) for all the composites is measured using the positron annihilation lifetime (PAL) spectroscopy. Linear attenuation coefficients are measured for unirradiated composite at 59.5 keV using 241Am γ‐source. Scan electron microscope, electrical conductivity, stress‐strain, and hardness tests are investigated for all the composites before irradiation at room temperature (25°C). The results show a good linear correlation between the open hole size evaluated by PAL spectroscopy and all of the measured properties. These correlations confirmed the important role played by the free volume (ie, is governed by the open hole size) in all of the electrical conductivity, mechanical, and transmission properties in the composite. The results status that, the composite sample EPDM/BR (0/100) may be used as a radiation resistant material or as a radiation protector for tools in high‐level radiation areas.

The degradation of the nearby generation of high-density polyethylene (HDPE) loaded with 2.5% of carbon black (CB) content (ie, HDPE/CB composites) is studied experimentally with the end goal of radiation safety applications. The impact of various γ-irradiation doses in the air on the nanostructure of free volume and durability has been researched. The free volume was evaluated utilizing the positron annihilation lifetime (PAL) technique while the durability was contemplated by measuring the mechanical properties such as strain, elongation at break, and tear resistance. The electrical conductivity was explored to demonstrate the impact of the irradiation dose on the conductivity of the samples. Surface morphology studies using a scanning electron microscope (SEM) showed the surface fracture of HDPE/CB composites for unirradiated and irradiated samples. The surface roughness of the HDPE/CB GMs increases with increasing the irradiation dose. Among various uses of HDPE/CB composites, sheets are liners of dumps used to dispose of interim storage for Low and Medium Level Waste of NORMs and TENORMs. HDPE Geomembrane liners proved its utilization from the results of present research of electrical, mechanical tests, and SEM morphology to have the required resistance to weather conditions.