Researchers at the University of South Florida have identified the mechanism that makes carbon black particles strengthen rubber, resolving a scientific puzzle that has lasted nearly a century. Their computer simulations reveal how the material resists stretching by effectively fighting against itself.
The team, led by engineering professor David Simmons, conducted 1,500 molecular dynamics simulations that totaled the equivalent of 15 years of computing time. Working with postdoctoral scholar Pierre Kawak and doctoral student Harshad Bhapkar, they showed that carbon black particles limit how much rubber thins when stretched. This forces the material to expand in volume, greatly increasing its stiffness and strength.