Microstructure formation of polymer surface by atomic oxygen beam

Goto, Aki*; Yamashita, Shinichi*; Kitamura, Akane; Tagawa, Masahito*

Atomic oxygen (AO) is a dominant component of the residual atmosphere at low earth orbit altitude. AO collides with spacecrafts at about 8 km/s, corresponding to a translational energy of about 5 eV. It causes a critical damage such as oxidation or erosion of polymers composing the spacecrafts. A previous study has reported that nano- and microscopic needle-like protrusions were formed densely on polymer surface by AO collision. In this study, we focus on the unique morphological change because it must be useful for a modified surface. Commercial films of low-density polyethylene (LDPE), polypropylene (PP), and polystyrene (PS) were irradiated with AO and their surfaces were observed by field-emission scanning electron microscopy (FE-SEM). Microscopic needle-like protrusions were formed uniformly at the surfaces of all samples, however, the uniformity decreased with increasing AO fluence due to degradation of the protrusions. The maximum protrusion density increased in the order of PP LDPE PS, showing that the density depends on the chemical structure of the polymer materials.