Dependence of Accelerating Voltage on Surface Hardness of PMMA by Low Energy Nitrogen Ion Irradiation

Poly methyl methacrylate (PMMA) has some excellent optical properties among polymer materials, such as low refraction. Accordingly, PMMA is utilized widely such as lens and optical fiber in optical category. But because of its low surface hardness, the surface is easily damaged, and the transparency decreases with time. Therefore, if the surface hardness of PMMA can be improved, it is expected that the industrial value of PMMA rises. So the authors irradiated low energy nitrogen ion on PMMA and measured the surface hardness using nanoindentation method. As experimental method, nitrogen ions which were generated by RF (radio frequency) plasma in nitrogen ambient atmosphere of about 10^-2 Pa were accelerated to about 100-1000 eV by accelerating electrode and were irradiated on PMMA. As a result, the surface hardness changes depending on the accelerating voltage. The paper will be summarized the experimental procedure and the result