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.

The environmental and ecological concerns drive researchers to synthesize functional materials using components from natural resources. Nanocellulose (NC), derived from plants, marine animals, or microorganisms, is a green material attracting attention due to its abundance, biocompatibility, and biodegradability. NC’s interstice properties enable the synthesis of functional nanocomposites in forms like aerogels, foams, paper, sheets, or hollow filaments. This review briefly describes NC classification and production while comprehensively presenting its mechanical, rheological, optical, and electrical properties, offering foundational knowledge for future research. Additionally, it highlights recent developments in NC-based products across fields such as papermaking, water treatment, civil engineering, electronics, cosmetics, food, and medicine. For the first time, this paper explores recent advances in NC molecular simulation, providing insights into structure, arrangement, and interactions through molecular dynamic simulation. Finally, future prospects for NC-based applications are discussed to encourage studies addressing current challenges.

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.

Carbon black migration between ground tire rubber (GTR) and rubber matrix is essential in developing high-performance rubber/GTR composites. In this work, carbon black N220 (surface area: 107.1 m²/g, particle size: 20–25 nm) and N660 (surface area: 33.1 m²/g, particle size: 49–60 nm) were used as the reinforcement fillers for styrene-butadiene rubber (SBR) blended with reclaimed GTR. The combined effects of GTR devulcanization level and carbon black grade on the properties of SBR/GTR composites were investigated considering curing characteristics, thermal stability, physico-mechanical properties, dynamic mechanical properties, swelling behavior, and morphology. The results showed that, regardless of GTR devulcanization level and carbon black grade, application of GTR resulted in deterioration of mechanical properties compared to a reference sample without GTR. It was observed the reinforcement effect of carbon black in SBR/GTR composites was more visible with higher devulcanization level of GTR and lower particle sizes of carbon black fillers. SBR/GTR composites reinforced with carbon black N220 were characterized by tensile strength in the range of 15.3–16.3 MPa and abrasion resistance in the range of 120–123 mm³, which justify their potential application in the manufacturing of technical rubber goods or footwear.

Epoxidized natural rubber with 50 mol% epoxide (ENR-50) was compounded with zinc chloride (ZnCl₂) and subjected to torque response analysis using a moving die rheometer. It was found that different ZnCl₂ concentrations (3, 5, 7, 9, and 12 millimoles (mmol)) mixed in ENR-50 exhibited positive torque responses, prompting further molecular characterization using Fourier transform infrared spectroscopy. The results indicated distinct absorption peaks at wavenumbers of 442 and 809 cm^–1, which signify the presence of –O–Zn–O– coordination linkages. The curing characteristics of ENR and ZnCl₂ compounds showed that increasing ZnCl₂ content resulted in higher minimum and maximum torque values, but also led to a decrease in scorch time and cure rate index (CRI). Moreover, higher ZnCl₂ concentrations enhanced the strength properties (tensile strength, moduli, stiffness, toughness, and hardness), crosslink densities, dynamic shear moduli, initial modulus during relaxation experiments, and thermal resistance, as evidenced by temperature scanning stress relaxation (TSSR), thermogravimetric analysis, and dynamic mechanical analysis. However, an increase in ZnCl₂ content led to a reduction in elongation at break due to the higher crosslink density within the coordination networks in the ENR matrix, which resulted in the movement constraint of the rubber vulcanizate.