Effect of fiber-reinforcement on tensile and dynamic performance of elastic rubber layers composed of recycled SBR

This study evaluates the mechanical and dynamic properties of elastic rubber layers reinforced with synthetic fibers—specifically polypropylene (PP), polyester (Pe), nylon (Ny), and carbon fibers (CF)—for application in synthetic sports surfaces. The investigation focuses on tensile behavior, shock absorption, and vertical deformation as a function of fiber type and volume fraction (0.5, 0.75, and 1.0 vol.%). The specialized biomechanical equipment known as the Artificial Athlete (AA) apparatus was utilized to provide a realistic assessment of the surfaces' dynamic performance during athletic activities. Preliminary chemical analysis confirmed that all constituent materials complied with environmental safety standards regarding harmful substances. Mechanical testing revealed that polymeric fiber (PP, Pe, and Ny) reinforcement significantly enhanced tensile strength by 162–226%, whereas CF reinforcement yielded negligible improvements due to the poor dispersion of bundled filaments. Although the addition of fibers had marginal effects on shock absorption and vertical deformation, all specimens successfully satisfied the standard requirements for these dynamic performances. Regarding ductility, fiber incorporation did not improve the elongation at break, which remained below the requirements of both European and Korean standards under ambient temperature curing. These findings suggest that it is essential to optimize the urethane resin content and implement elevated curing temperatures in conjunction with fiber reinforcement to ensure the elastic rubber layers exhibit performance sufficient to meet the required criteria. ● Biomechanical AA apparatus was used to replicate realistic human heel-strike impacts. ● Polymeric fiber reinforcement increased tensile strength of elastic rubber layer by up to 226%. ● Carbon fibers showed negligible effects on tensile performance due to poor dispersion. ● Tensile efficiency depends on the balance between fiber surface area and resin dosage. ● All composites met international EN/KS standards for dynamic shock performance. ● Elevated curing temperatures are essential to satisfy mandatory ductility thresholds.