S. Chen, L. H. Han, W. Zhang, University of Texas at Austin, Austin, TX
We report direct laser ablation of high-density polyethylene (HDPE) filled with carbon nanofibers using a pulsed Nd:YAG laser. Both 532 nm and 355 nm wavelengths with a spot size of 40 m
m were used for the study. The laser fluence was varied from 0.8 μJ/cm2 to 3.8 μJ/cm2. Material pop-up occurred near the threshold energy, while open holes were achieved with higher laser energy. The etching depth increased linearly with the number of pulses. Although polyethylene was transparent to the laser beam, the carbon nanofibers added to the polymer matrix absorbed the laser energy and converted it into heat. Numerical heat conduction simulation shown the HDPE matrix was partially melted or evaporated, due to pyrolytic decomposition. Also we would like to report on a laser-assisted photothermal imprinting method for directly patterning carbon nanofiber-reinforced polyethylene nanocomposite. A single laser pulse from a solid state Nd:YAG laser (10 ns pulse, 532 nm and 355 nm wavelengths) is used to melt/soften a thin skin layer of the polymer nanocomposite. Meanwhile, a fused quartz mold with micro-sized surface relief structures is pressed against the surface of the composite. Successful pattern transfer is realized upon releasing the quartz mold. Although polyethylene is transparent to the laser beam, the carbon nanofibers in the high density polyethylene (HDPE) matrix absorb the laser energy and convert it into heat. Numerical heat conduction simulation shows the HDPE matrix is partially melted or softened, allowing for easier imprinting of the relief pattern of the quartz mold.
Summary: We report direct laser ablation of high-density polyethylene (HDPE) filled with carbon nanofibers using a pulsed Nd:YAG laser. Both 532 nm and 355 nm wavelengths with a spot size of 40 ƒÝm were used for the study. The laser fluence was varied from 0.8 £gJ/cm2 to 3.8 £gJ/cm2. Material pop-up occurred near the threshold energy, while open holes were achieved with higher laser energy. The etching depth increased linearly with the number of pulses. Although polyethylene was transparent to the laser beam, the carbon nanofibers added to the polymer matrix absorbed the laser energy and converted it into heat. Numerical heat conduction simulation shown the HDPE matrix was partially melted or evaporated, due to pyrolytic decomposition.
Also we would like to report on a laser-assisted photothermal imprinting method for directly patterning carbon nanofiber-reinforced polyethylene nanocomposite. A single laser pulse from a solid state Nd:YAG laser (10 ns pulse, 532 nm and 355 nm wavelengths) is used to melt/soften a thin skin layer of the polymer nanocomposite. Meanwhile, a fused quartz mold with micro-sized surface relief structures is pressed against the surface of the composite. Successful pattern transfer is realized upon releasing the quartz mold. Although polyethylene is transparent to the laser beam, the carbon nanofibers in the high density polyethylene (HDPE) matrix absorb the laser energy and convert it into heat. Numerical heat conduction simulation shows the HDPE matrix is partially melted or softened, allowing for easier imprinting of the relief pattern of the quartz mold.
