We investigated the possibility of applying rejected natural rubber gloves (RNRGs) as a matrix for rubber composites filled with sepiolite. The virgin natural rubber (NR) samples were also prepared for comparison. Clearly, the RNRGs can be re-mixed with rubber chemicals, re-shaped, and revulcanized. Maximum torque increased with sepiolite loading during vulcanization, along with stress at 100 and 300% strains and strain-induced crystallization ability, whereas the tensile strength and elongation at break of the RNRG composites exhibited an opposite trend. The unfilled RNRG possessed high tensile strength (~19.86 MPa) and extensibility (~600%), which was about 67% higher than that of the unfilled NR sample. However, increased sepiolite loading decreased the thermomechanical properties of the RNRG composites because the RNRG had undergone vulcanization before re-mixing and revulcanizing; the NR-based composite showed the opposite trend. Based on the results, the RNRGs can be re-used as the rubber matrix of rubber compounds when thermal properties are not critical.

Conventional sulfur vulcanization in rubber manufacturing depends on elevated curing temperatures and zinc oxide activators, resulting in high energy consumption and increasing environmental concerns associated with zinc release. To overcome these limitations, a novel graphene oxide (GO)-supported rare-earth-containing accelerator (GO–LZC) was designed by coordinating lanthanum(III) and zinc(II) ions with sodium diethyldithiocarbamate (DC). At the same time, the oxygen-containing groups on GO further participated in ligand coordination. The resulting GO-immobilized complex exhibits a well-defined chelating structure and uniform nanoscale dispersion, which together enhance the accessibility and reactivity of active sulfurating species during curing. When incorporated into solution-polymerized styrene–butadiene rubber (SSBR), GO–LZC markedly promotes crosslink formation at reduced thermal input. Kinetic analysis reveals a substantial decrease in the apparent activation energy, and curing and mechanical tests confirm that efficient vulcanization can be achieved at 130 °C, representing a 20–40 °C reduction relative to typical industrial curing conditions. This work demonstrates a viable strategy for developing low-zinc, energy-efficient, and high-performance vulcanization systems. It highlights the potential of rare-earth/GO hybrid catalysts for sustainable rubber processing.

This is an editorial article. It has no abstract.

In this study, the effect of the amount of blowing agent and the type of sulfur curing system on the cellular structure, thermal, and mechanical properties of ethylene-propylene-diene monomer (EPDM) foam was investigated. Three types of sulfur curing systems including efficient, semi-efficient and conventional and three variable levels of azodicarbonamide (ADC) were considered; as a result, nine EPDM foam formulations were evaluated. Curing process parameters were measured using cure rheometry and cellular structure was examined by optical microscopy images, determining the average cell size and size distribution. For evaluating physical and mechanical properties, density and compression set tests were performed. Thermal conductivity tests were conducted on selected samples. Building energy modeling was performed using DesignBuilder software to evaluate the thermal insulation performance of the foams. The results showed that the type of curing system and the amount of ADC significantly affect cell morphology, density, and mechanical properties. Overall, a decrease in density leads to reduced mechanical properties. The modeling results indicated that using EPDM foams as building thermal insulation can reduce the energy consumption of heating, ventilation, and air conditioning (HVAC) systems by up to 20%.

Ground sugarcane bagasse (GSB), an agro-waste rich in lignocellulosic components, was studied as a sustainable bio-filler in natural rubber (NR) tread compounds to lessen reliance on petroleum-derived carbon black (CB). A control formulation with 45 phr CB was compared to hybrid formulations with 40, 35, and 30 phr CB mixed with 5, 10, and 15 phr GSB. Tensile strength 13.1 MPa, elongation at break 700%, and hardness 67 Shore A were all optimally balanced by the compound containing 10 phr GSB (S2), while also exhibiting good cure behavior and thermal stability. Improved tire performance characteristics were confirmed by a dynamic mechanical study, which showed that tan δ at 60 °C decreased by 8.0% (resulting in lower rolling resistance) and increased by 3.9% (improving wet traction) at 0°C. The Payne effect showed improved filler dispersion as a result of GSB partially replacing CB. The results show that appropriately dispersed GSB can partially reinforce NR, enhancing energy efficiency and sustainability. However, larger GSB loadings decrease modulus, tear strength, and abrasion resistance due to lower interfacial adhesion and the presence of micro-voids. According to this study, pulverized sugarcane bagasse shows promise as an environmentally friendly filler for green tire applications, promoting the circular economy and lowering the carbon footprint of rubber compounding.