Surface Coating of Aramid Fiber by a Graphene/Aramid Nanofiber Hybrid Material to Enhance Interfacial Adhesion with Rubber Matrix

Aqueous Dispersion of Aramid Nanofibers Achieved by Using Tannic Acid for Ultrahigh Strength Films

Polymer nanofibers have established a robust foundation and possess immense potential in various emerging fields such as sensors and biotechnology. In this study, aqueous dispersions of aramid nanofibers (ANFs) were successfully prepared by using tannic acid (TA). Morphological analysis revealed that TA effectively prevented self-aggregation of ANFs, and preserved the nanofiber structure during TA-assisted solvent exchange. Subsequently, the ANF and TA/ANF films were fabricated using casting and vacuum-assisted filtration techniques. Notably, the tensile strength of the casting TA/ANF film reached 393.8 MPa, exhibiting a remarkable improvement of 41.3% compared to that of the pure ANF film. These exceptional mechanical properties can be attributed to the well-dispersed nanostructures, hydrogen-bonding interactions, zigzag structures, and fiber-bridging effects. Furthermore, the TA/ANF film demonstrated superior ultraviolet (UV) shielding capabilities, visible transparency properties, and excellent resistance to chemical reagents. The above-mentioned interesting findings demonstrate its potential as a nanofiber-reinforced material for poly(vinyl alcohol) (PVA) composites.

Graphene-Based Hybrid Fillers for Rubber Composites

Graphene and its derivatives have been confirmed to be among the best fillers for rubber due to their excellent properties, such as high mechanical strength, improved interface interaction, and strain-induced crystallization capabilities. Graphene rubber materials can be widely used in tires, shoes, high-barrier conductive seals, electromagnetic shielding seals, shock absorbers, etc. In order to reduce the graphene loading and endow more desirable functions to rubber materials, graphene-based hybrid fillers are extensively employed, which can effectively enhance the performance of rubber composites. This review briefly summarizes the recent research on rubber composites with graphene-based hybrid fillers consisting of carbon black, silica, carbon nanotubes, metal oxide, and one-dimensional nanowires. The preparation methods, performance improvements, and applications of different graphene-based hybrid fillers/rubber composites have been investigated. This study also focuses on methods that can ensure the effectiveness of graphene hybrid fillers in reinforcing rubber composites. Furthermore, the enhanced mechanism of graphene- and graphene derivative-based hybrid fillers in rubber composites is investigated to provide a foundation for future studies.

Fabrication of silver ions aramid fibers and polyethylene composites with excellent antibacterial and mechanical properties

Nowadays, with the continuous understanding of the pathogenic mechanism of bacterium, the demand for antibacterial plastic products had significantly increased. Besides that, many counties issued mandatory standards for plastic products, which imposed strict requirements on ash content to prevent the addition of excessive inorganic matter to plastics in order to avoid weakening the properties of plastics and deteriorating the recyclable property. Based on this, the development of composites with organic fiber-loaded antibacterial agents is of practicable value and urgency. We used an open-ring addition reaction to modified aramid fiber (AF) by utilizing epoxypropyltrimethoxysilane to react with the reactive groups on the surface of AFs. Subsequently, the modified fibers were surface loaded with silver ionic glass beads. After that, a series of high-density polyethylene composites with excellent mechanical properties and antibacterial properties were prepared using melt mixing method. It was shown that the composite had a low ash value (1.88 wt%) even at a higher filling concentration (7 wt%) and the fibers could change the crystalline properties and morphology of the composite. Because of the fiber reinforcement and crystallization induction effects, the tensile strength and elasticity module of the composites could be improved by 141% and 136%, respectively. In addition, the composites had excellent long-lasting contact antibacterial effects against the inhibition of E. coli. The proposed organic fiber loading technique and antibacterial composites will provide a method for designing and preparing eco-friendly and high-performance plastic products.