THE EFFECTS OF POLYETHYLENES' STRUCTURE ON ITS INTERACTION WITH A SIMULATED LEO ENVIRONMENT

摘要

The present work studies the interactions of four different types of polyethylene (PE) surfaces with RF oxygen plasma components, simulating LEO environment. The samples were exposed in the plasma afterglow, with and without the plasma generated VUV radiation. The polymers studied were LDPE, UHMWPE, HDPE, and Composite Polyethylene having crystalline-to-amorphous phases ratio of 65%, 74%, 87% and 92%, respectively. Erosion of the LDPE, UHMWPE, and HDPE samples under AO irradiation showed an etching rate dependence on the degree of crystallinity. The addition of VUV radiation to the AO flux resulted in a significant increase of the etching rate, associated with a decrease of the total oxygen uptake, for the low crystallinity polymers, and an increase of the surface roughness. The Composite Polyethylene, although highly crystalline, revealed similar erosion rate and chemical composition changes as highly amorphous LDPE. The erosion mechanism of the different PE samples under AO or AO+VUV is discussed in terms of the initial internal structure.