Scientists Solve Rubber's Century‑Old Toughness Mystery

USF engineers simulated reinforced rubber—rubber with carbon black—and published in Proceedings of the National Academy of Sciences, showing that carbon black creates a Poisson’s ratio mismatch that prevents thinning and boosts volume, stiffness, and strength; by combining particle networks, sticky interactions, and space-filling effects, they offer a unified explanation that could reduce design trial-and-error and improve safety for critical infrastructure.