Ron Intrater

Ultra Violet & Atomic Oxygen Effects on Different Polyethylene Types: Reconstruction into Row-structure on the Surface of Extended Uhmwpe Fibers After Exposure to Oxygen and Uv Radiation Ron Intrater

External surfaces of spacecrafts in low earth orbit (LEO) are exposed to atomic oxygen (AO) and solar UV radiation. The present work studies the interaction of various polyethylenes with different RF oxygen plasma components. Erosion ot the samples showed an etching rate that is dependent on the degree of crystallinity: the higher the crystallinity level the lower the erosion rate. The addition of VUV radiation to the AO flux resulted in a significant increase of the etching rate. A process is reported whereby ordered nano domains are formed and a morphological reconstraction is generated into row-structure on the surface of Ultra- strong, UHMWPE fibers as aresult of the simultaneous exposure to oxygen and UV radiation in the afterglow of RF oxygen plasma. The orientation of the rows is perpendicular to the fiber direction. A possible explanation for this phenomenon is that the combined irradiation resulted in selective etching of the amorphous phase and release of polyethylene nano- rods of which the fiber is composed. Subsequently these nano-rods self-assembled on the surface of the fiber into row-structure.