An antibacterial natural rubber (NR) latex film was successfully prepared in this study. This was done by coating silver (Ag) nanoparticles onto the surface of the NR latex film. The Ag nanoparticles were synthesized using green tea (GT) extract as a bio-reducing agent. The corresponding Ag nanoparticles were then deposited onto the NR latex film. Before synthesis, the phenolic compounds were identified using high-performance liquid chromatography (HPLC). The Ag nanoparticles were found to be smaller than 25 nm in size. Subsequently, an experimental evaluation was conducted to determine the influence of deposition time, namely 1 to 20 min, on the film’s overall performance. Scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (SEM-EDX) confirmed that the Ag content was higher over the deposition time. The surface roughness of the samples was also screened by atomic force microscopy (AFM), where the films became rougher over the deposition time, confirming that Ag nanoparticles dispersed over the surface. As for the antibacterial activities, both qualitative and quantitative tests showed significant outputs. The clear zones of S. aureus and E. coli increased over the deposition time, and a shorter contact time was used to kill the bacteria. This study offers a scientific foundation that supports the development of future rubber products utilizing these findings.

A nanocomposite of styrene butadiene rubber (SBR) and multi-walled carbon nanotubes (MWCNT) was fabricated using an internal melt mixer. Systematically investigated the role of MWCNT loading on the mechanical, dielectric, electrical and Electromagnetic interference (EMI) shielding characteristics of developed nanocomposites. The fine dispersion of MWCNTs in the SBR matrix was clearly observed from high-resolution transmission electron microscope images. The nanocomposites exhibited outstanding electrical, dielectric and EMI shielding behaviours (~45 dB at 20 phr of MWCNT). A high conductivity of 0.92 S/cm was attained in the nanocomposites and is attributable to the establishment of percolation networks of MWCNT in the SBR matrix. These composites displayed reasonably good mechanical properties because of the reinforcing effect of MWCNT. The economically viable and easy fabrication protocol of this nanocomposite can act as a platform for the synthesis of low-cost and highly effective composite for EMI shielding applications.

Cross-linking frequently enhanced the mechanical properties of linear polymeric materials; however, it also resulted in the transition from thermoplastic to thermosetting materials, which posed issues from an environmental perspective. Thermoplastic polyurethane (TPU) elastomers were extensively applied across various industries. To improve the mechanical properties of TPU while preserving its environmental benefits, this study integrated radical copolymerization technology to develop a reversible crosslinked TPU. Specifically, the linear polyurethane molecular chains were crosslinked using diallyl disulfide (DADS) as a functional cross-linking monomer. Through radical copolymerization reactions, reversible crosslinks formed from disulfide bonds were created between the linear polyurethane molecular chains, yielding a self-healing reversible crosslinked thermoplastic polyurethane (DSTPU). The study showed that DSTPU could self-heal and dissolve under UV light and alkaline N,N-dimethylformamide (DMF) conditions, achieving 82.2% self-healing efficiency at 3 phr DADS. It dissolved into fine particles in alkaline DMF. Disulfide bonds in DSTPU enhanced cross-linking, boosting 19% oxygen permeability, thermal conductivity (0.218 W/(m·K)), and mechanical properties like tensile stress (11.18 MPa), force (134.13 N), and elongation (548%). These bonds also enhanced aging resistance, cutting ΔYI to 6.0%.

Natural rubber (NR) composites filled with silica and crosslinked with phenolic resin were prepared in this study. The influence of a small sepiolite addition (1–5 part(s) per hundred parts of rubber, phr) on the properties of NR composites was studied. It was found that sepiolite reduced silica aggregate size, allowing improved dispersion in the NR matrix. Sepiolite facilitates silica dispersion by locating at the silica surfaces and acting as a barrier that prevents agglomeration of silica filler. The swelling resistance, crosslink density, tensile strength, and strain-induced crystallization were all strengthened by incorporating sepiolite because of the improved silica dispersion. The greatest tensile strength was achieved at a 2 phr sepiolite addition level. The improvement was about 18% over the reference composite due to the greatest filler-rubber interactions and the finest filler dispersion. The results clearly indicate that sepiolite clay can be applied as a dispersing agent in silica-containing rubber composites.

This paper extends previous studies by the authors that aimed to describe the effect of apparent cross-link density (CLD) of the rubber polymer networks on the fracture mechanism caused by cut and chip (CC) wear of natural rubber (NR), demonstrating the positive effect of conventional vulcanization (CV). This work is focused on the determination of the effect of CLD while keeping constant the accelerator-to-sulfur ratio A/S = 0.2, typical for CV systems. For this ratio, different sulfur quantities were chosen, and the concentration of the accelerator N-tert-butyl-benzothiazole sulphonamide (TBBS) was calculated to achieve CLDs in a range from 35 to 524 μmol・cm^–3. Standard analyses such as tensile tests, hardness, rebound resilience and DIN abrasion were performed. From these analyses, the optimum physical properties of the NR-based rubber were estimated to be in the CLD range of approximately 60 to 160 μmol・cm^–3. A CC wear analysis was performed with an Instrumented cut and chip analyzer (ICCA) and it was found that the highest CC wear resistance of the NR is in the CLD range of 35 to 100 μmol・cm^–3. Furthermore, the effect of straininduced crystallization (SIC) of NR on CC wear and its dependence on the CLD region was discussed. For the first time, we determine a CLD range for a CV system in which the material achieves both optimal mechanical properties and CC wear resistance.