Influence of applied electron radiation on the properties of a polyamide 11 surface layer

This article deals with the influence of the radiation cross-linking of polyamide 11 (PA 11) on the mechanical properties. The aim of this study is to provide more detailed knowledge of the relation between the radiation dosage and the properties of cross-linked PA 11 and its mechanical behaviour. Electron-beam-unmodified and modified PA 11 test samples were exposed to electron radiation with dosages from 0 kGy to 198 kGy, which were graded at 33 kGy. The surface-layer properties of the modified PA 11 were tested using a state-of-the-art indentation technique, which detects the immediate change in the indentation depth, depending on the applied force. The evaluation of the measured mechanical properties (indentation hardness, modulus and creep) was done by the Oliver and Pharr method. A significant influence of the radiation cross-linking on the PA 11's mechanical properties improvement was confirmed by the measurements. This enhancement grows with the increasing radiation dosage. Due to the electron-radiation modification of PA 11, the mechanical properties of the surface layer were increased by up to 59 % compared with the unaltered material. Radiation crosslinking is an important thermoplastic modification method by which the desired properties can be achieved in a relatively short period of time. The main advantage is that the process is executed on the final product.European Regional Development Fund under the project CEBIA-Tech Instrumentation [CZ.1.05/2.1.00/19.0376]; Ministry of Education, Youth and Sports of the Czech Republic within the National Sustainability Program [LO1303 (MSMT-7778/2014)]; Internal Grant Agency of TBU in Zlin [IGA/2020/003