Hydrogenated acrylonitrile–butadiene rubber (HNBR) is widely used in automotive and sealing applications due to its oil resistance and mechanical durability; however, its long-term performance is significantly influenced by the curing chemistry. Sulfur vulcanization offers superior elasticity but restricted thermal stability, while peroxide curing improves heat resistance at the expense of flexibility. In this study, we investigate hybrid sulfur–peroxide curing to integrate these benefits. The hybrid pathway encompasses competitive and sequential processes, such as partial radical quenching and accelerator oxidation, resulting in a dual crosslink network. Dynamic mechanical, thermal, and temperature scanning stress relaxation (TSSR) evaluations demonstrate that hybrid systems provide precise modulation of the operational temperature–frequency range, broaden the glass-transition relaxation, and control stress dissipation. The coexistence of sulfur and C–C crosslinks results in a heterogeneous structure characterized by diverse crosslink densities and bond energies, leading to numerous relaxation modes and an optimal blend of elasticity, strength, and thermal stability. Microscopy confirms the absence of phase separation, indicating that hybrid vulcanization is a viable approach for producing robust, high-performance HNBR elastomers.

This study investigates the effects of renewable chopped cellulose fiber (CCleF) on the physical and mechanical properties, oil resistance, and thermal-oxidative aging behavior of acrylonitrile-butadiene rubber (NBR), aiming to determine the optimal filler content. CCleF/NBR composites with varying CCleF loadings were prepared and systematically characterized through analyses of vulcanization behavior, three-dimensional morphology, mechanical properties, thermal-oxidative aging, and oil resistance. The results indicate that the composite with 3 phr CCleF exhibits uniform fiber dispersion and optimal overall performance, showing enhanced processability, a reduced vulcanization time, and improved physical and mechanical properties. After thermal-oxygen aging, the composite demonstrated superior stability: the percentage change in tensile modulus, rebound resilience, and DIN abrasion decreased significantly by 13.73, 49.82, and 74.9%, respectively, while the aging coefficient reached 0.86. Notably, this composite also exhibited excellent oil resistance, with a volume expansion rate of 7.24%, which is 13.1% lower than that of unfilled NBR. Correspondingly, the tensile product’s retention rate decreased by 37.72%, while rebound resilience and abrasion resistance improved. This study demonstrates that incorporating 3 phr CCleF is a practical approach to achieving high-performance NBR, providing a material basis for its use in demanding environments such as the petrochemical industry.

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%.

This study explores the application of thermo-oxidative reclaimed ground tire rubber (RGTR) in natural rubber (NR)/styrene butadiene rubber (SBR) composite, focusing on its impact on morphology, mechanical properties, rheological behavior, vulcanization characteristics, aging resistance, tear strength and abrasion resistance. The findings revealed that RGTR enhances the tear strength and abrasion resistance of NR/SBR composites while maintaining comparable tensile strength, elongation at break, and modulus. The incorporation of RGTR reduced Mooney viscosity of the NR/SBR composites and improved flowability. It also shortened the vulcanization time and enhanced vulcanization efficiency. The NR/SBR composites with RGTR loadings below 60 phr exhibited optimal performance, achieved a maximum tear strength of 93.77 N/mm and improved abrasion resistance. However, higher RGTR content led to increased agglomeration, as evidenced by scanning electron microscopy (SEM), which showed finer dispersion at lower RGTR contents and larger aggregates at higher loadings. These findings demonstrate the potential of RGTR as a sustainable additive for enhancing specific properties in NR/SBR composites, contributing to both performance optimization and waste tire management.

The present study has proposed a straightforward method to improve the reprocessability of modified natural rubber (NR) by blending it with gelatin (GT). The reprocessable characteristics of these blends were evaluated based on their remolding capabilities and mechanical recovery performance. In this method, poly(vinylbenzyl chloride) (PVBC) was first grafted onto NR chains to create graft copolymers known as NR-g-PVBC. The benzyl chloride groups in the graft copolymers were subsequently converted into quaternary ammonium groups, referred to as NR-g-QPVBC. This modification enabled ionic crosslinking when NR-g-QPVBC reacted with ethylenediamine tetraacetic acid. Blends were created by incorporating GT powder into the NR-g-QPVBC latex. The optimal loading level of GT was determined to be 30 wt%, as the resulting film exhibited the highest recovery of tensile properties. Initially, the film's tensile strength was measured at 15 MPa. After being remolded at 160 °C, the tensile strength decreased to 9.3 MPa, resulting in a recovery rate of 60.7% and withstanding a tensile strain of 144%. Although the NR-g-QPVBC/GT films could be remolded, their tensile properties declined with increasing remolding cycles. Therefore, this work demonstrated a practical method for producing NR-based films that could be reshaped through hot-pressing after being formed into products, increasing their reusability.