Measurement of Surface and Shallow depth Changes of Polypropylene Due to Gliding Discharge Plasma

Research subject: 

Polypropylene (PP) is a thermoplastic polymer that is used in a wide range of applications, including films and sheets, blow molding, injection molding, food packaging, textiles, laboratory and medical equipment, pipes, industrial and construction applications, and the manufacture of automotive components. In the applications of this polymer, improving the surface of PP has been considered. One of the usual methods for improving the surface is the cold plasma method. Plasma is a chemically highly active environment where there are many ions and radicals. In this research, atmospheric pressure gliding discharge plasma was used to increase the hydrophobicity of PP and the surface and depth changes of PP were investigated.

Research approach: 

The depth and surface changes of PP were investigated by radiating the gliding discharge plasma to the PP polymer surface at the different times. FTIR and XRD tests were performed to investigate volume changes and FESEM investigated the surface changes. The hydrophobicity of PP was investigated by contact angle (CA) test and positron lifetime spectroscopy (PALS) was used to investigate shallow depth changes.

The results show that the applied cold plasma did not cause volumetric changes in PP, but caused surface changes and roughness. In this polymer, the contact angle has increased from 30.1 ± 0.1 to 34.4 ± 0.1 and the hydrophobicity of the surface has increased. Examining the changes in holes by PALS test shows that after plasma irradiation the volume of the holes increased from 217 Å3 to 222 Å3 and their intensity decreased. This is due to the heat of the plasma and the energy of its particles.:The results show that the cold plasma caused surface and depth changes and the contact angle increased from 30.1 ± 0.1 to 34.4 ± 0.1 and the hydrophobicity of the surface increased.