Nanomechanical mapping on the deformed poly(ε-caprolactone)

Quantitative investigation of both the on-site morphology and mechanical properties of stretched semicrystalline polymer, poly(ε-caprolactone) (PCL), by nanomechanical mapping, was reported. PCL films were prepared by a micro-twin-screw extruder and were cut into dog-bone shape and uniaxially stretched at a fixed elongation of 700∓10% by a tensile tester. The results show that the cryo-microtome processing and slight relaxation after microtoming has an effect on the calculated Young's moduli of the polymer. On the basis of the nanomechanical mapping and combined with existing studies on the deformation behavior of PCL,34 the orientated hierarchical structure and its microscopic mechanical property in the necking part are revealed. In the high strain, heterogeneous intralamellar slip results in the formation of both orientations and entanglements of the nanofibrils, which is harder than neat polymer matrix and shows higher Young's modulus.