Tuesday, November 10, 2015: 2:15 PM
251A (Salt Palace Convention Center)
We demonstrate that commercially available core-shell rubber (CSR) nanoparticle additives can improve ballistic impact performance by over 180% for epoxy resins with glass transition temperatures in a range between 60 and 110°C, without large reductions in Tg or stiffness. The ballistic impact performance of modified epoxies covers a transition from brittle to tough behavior which is shown using SEM fractographs to be due to a change in failure mechanism. For brittle resins, failure is dominated by initiation of Hertzian cone fracture which depends strongly on fracture toughness KIC, while for tough resins, failure is dominated by plastic yield at the impact site and is independent of fracture toughness above a minimum KIC value of about 1.1 MPa-m1/2. The insights gained from this study are valuable for design of next generation composite matrices for lightweight protective applications.