Effects of short-fiber shape on tensile properties of reinforced rubber

The tensile properties under various conditions were investigated to ascertain the optimum conditions to yield the best tensile properties. Fiber aspect ratio (AR: length of fiber/diameter of fiber), diameter ratio (DR: sphere diameter of dumbbell/diameter of fiber), interphase condition and fiber content were all considered as variables which impact the tensile strength, tensile moduli, pull-out force. In general, under good interphase conditions the tensile strength increased when the fiber aspect ratio was more than 20. The short-fiber reinforced SBR with a big end (DR = 3) did not show the dilution effect under interphase conditions when the fiber aspect ratio was more than 20. In case of short-fiber reinforced NR, when the specimen had DR = 3 and AR≥20, the dilution effect only showed up in the no-coated one. The tensile moduli were significantly improved due to the fiber aspect ratio, fiber content and good interphase at the same diameter ratio. The pull-out force increased with the diameter ratio, and keeping the diameter ratio the same, better interphase conditions also resulted in a higher pull-out force. Overall, it was found that the fiber aspect ratio, fiber diameter ratio, and interphase condition all have an important effect on tensile properties.