Multi-scale polymer properties with applications to solid lubricants in ironing

The use of polymer laminated steels have received significant interest from the can-making industry as a potential base material, mainly due to environmental benefits and excellent solid lubrication properties. Internal corrosion prevention is also very important with food cans. Previous research has experimentally and mathematically analyzed this material, but the mechanical properties, especially the shear strength, of the polymer coating is difficult to obtain given its very small thickness. This paper obtains predictions of polymer coating strength through two approaches: a millimeter-scale approach based on a mathematical model of ironing, and a sub-micrometer scale approach based on asperity plowing with an atomic force microscope. Once piezo-strengthening effects are accounted for, the polymer strength predictions from the two methods are very close.