Shuai Zhao

Accelerated vulcanization is a key approach to overcoming a critical bottleneck in NBR, where the strong electron‐withdrawing effect of cyano groups reduces double‐bond reactivity and leads to prolonged vulcanization times. This work uses acrylonitrile‐butadiene latex LZ3305 as the matrix to prepare a series of NBR composites with combined accelerators and antioxidants. We investigate the synergistic formulation of the accelerators zinc diethyldithiocarbamate, zinc dibenzyldithiocarbamate (ZTC), and a self‐made amine antioxidant (ST) via a wet compounding process. Our goal is to develop a specialty fast‐curing NBR that simultaneously possesses storage stability and aging resistance. We use a fast‐curing NBR from LANXESS (NBR3445F) as the reference. Our results show that the NBR/5EZ‐0.8ST composite achieves the highest cure rate index of 0.337 and significantly improved storage stability. After 1 month of storage at room temperature, its Mooney viscosity retention rate reaches 97%, which is an 87% improvement over NBR3445F. SEM images reveal a uniform filler dispersion in the NBR/7EZ‐0.6ST composite, with no visible cracks on the surface after aging. The results demonstrate that the formulation containing antioxidant ST effectively addresses the low efficiency of conventional vulcanization processes through synergistic effects. These findings establish a theoretical basis for developing highly efficient, durable, and fast‐curing NBR.

This study aims to reduce the environmental impact of traditional rubber vulcanization by proposing a greener process. Accelerators and emulsifiers were introduced into acrylonitrile‐butadiene rubber (NBR) using a wet mixing method after polymerization, thereby improving dispersion and efficiency. Two accelerator systems, RH‐EZ and RH‐ZTC, were constructed based on NBR LZ3305 and compared with the commercial fast‐curing NBR3445F. The results revealed distinct advantages for each system. The RH‐EZ system significantly enhanced the vulcanization rate (reducing t ₉₀ ), with NBR/19RH‐EZ showing a 67% reduction over base LZ3305 and about 43% compared to NBR3445F. Conversely, the RH‐ZTC system excelled in processability and low‐temperature properties; NBR/13RH‐ZTC maintained 95% of its initial Mooney viscosity after 30 days, and NBR/17RH‐ZTC achieved a glass transition temperature of −25.4°C. Both systems exhibited excellent mechanical strength, crosslink density, and oil resistance. The Coran model confirmed that the RH‐EZ system effectively increased the E _precursor and E _crosslinking of the base LZ3305. This research provides a new pathway for preparing high‐performance, low‐carbon, and efficient vulcanized NBR and is expected to enable green and low‐carbon production of NBR.

Flame‐retardant rubber materials for conveyor belts have long relied on traditional halogen/antimony flame‐retardant systems, which tend to increase hardness and reduce abrasion resistance. In this study, a natural rubber/polybutadiene rubber (NR/BR) composite with low hardness, high abrasion resistance, and adequate flame retardancy was developed. A phosphorus/nitrogen/aluminum (P/N/Al) synergistic flame‐retardant system based on halogen‐free aluminum diethylphosphinate (ADP) and melamine (MEL) was constructed, together with a phosphorus‐based plasticizer, tris(isopropylphenyl) phosphate (IPPP‐95), to improve processability and mechanical properties. As a result, an NR/BR composite with excellent overall performance was successfully prepared. Compared with the conventional chlorinated paraffin/antimony trioxide system, the NR/BR/L40 formulation (containing 40 phr of Longsafe 207) maintained a Shore A hardness of approximately 50, significantly increased the limiting oxygen index (LOI) to 26.5%, achieved a UL‐94 HB rating (which is acceptable for conveyor belt applications), and exhibited a DIN abrasion loss of 194 mm ³ . This formulation successfully achieves a favorable balance among adequate flame retardancy, high abrasion resistance, and low hardness, providing a viable technical route for the development of high‐performance flame‐retardant conveyor belts for mining applications.

The burning of Ethylene–Propylene–Diene Monomer (EPDM) rubber generates substantial smoke, posing a severe threat to the environment and personal safety. Considering the growing emphasis on safety and environmental protection, conventional non-smoke-suppressing flame retardants no longer satisfy the present application requirements. Consequently, there is an urgent need to develop a novel flame retardant capable of suppressing smoke formation while providing flame retardancy. Sepiolite (SEP), a porous silicate clay mineral abundant in silica and magnesium, exhibits notable advantages in the realm of flame retardancy and smoke suppression. This research focuses on the synthesis of two highly efficient flame-retardant smoke suppression systems, namely AEGS and PEGS, using Enteromorpha (EN), graphene (GE), sepiolite (SEP), ammonium polyphosphate (APP), and/or piperazine pyrophosphate (PPAP). The studied flame-retardant systems were then applied to EPDM rubber and the flame-retardant and smoke suppression abilities of EPDM/AEGS and EPDM/PEGS composites were compared. The findings indicate that the porous structure of sepiolite plays a significant role in reducing smoke emissions for EPDM composites during combustion.

Rubber compounds with high friction coefficients are widely used in safety shoes, functional shoes, etc. However, in the presence of a liquid lubrication layer, friction coefficients between rubber compounds and the opposing surface are generally very low. In this work, friction coefficients of rubber compounds are improved by a two‐pronged method. First, micron silicon carbides (SiC) with irregular shape and knife‐edge are selected as fillers to improve the plowing friction in dry state, and to improve the adhesive friction in wet state via piercing the liquid lubrication layer. Second, tackifying phenolic resin is added to increase the damping performance of rubber compounds, so as to improve the hysteresis friction in both dry and wet states. The results show that the comprehensive static and dynamic friction properties of rubber compounds are the best in both dry and wet states (0.5 wt% sodium dodecyl sulfate solution or 90 wt% glycerol solution), when SiC size is 7–14 μm and SiC content is 75–90 phr. Phenolic resin can increase the loss factor (tanδ) and loss modulus (E") of rubber compounds, and improve the static and dynamic friction coefficients in wet state (90 wt% glycerol solution). At the same time, it can improve the hardness of rubber compounds and reduce the relative content of SiC, thus reducing the static and dynamic friction coefficients of rubber compounds in dry and wet states (0.5 wt% sodium lauryl sulfate aqueous solution). In general, the optimal content of phenolic resin is 10–15 phr. Highlights: Rubber friction coefficients improved via both adhesion and hysteresis friction. Irregular silicon carbides pierce liquid layer to improve adhesive friction of rubber. Phenolic resin increases hysteresis friction of rubber via damping property.