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Positron annihilation lifetime measurements were performed on polyethylene films [low-density polyethylene and ultra-high molecular weight polyethylene (UHMWPE)] with a thickness of 15–2000 μm using a Na-22 positron source enclosed in a Kapton film. For thin films, some positrons will pass through the film and annihilate behind it. Using a single film in a commercial anti-coincidence system, by placing an annealed stainless steel (SUS304) cover behind the sample, it is possible to sufficiently measure the long-lifetime ortho-positronium (o-Ps) component even in thin films. Additionally, calculated intensities of the o-Ps component determined from the estimated film transmittance agreed well with the measured values. Furthermore, by applying this method to uniaxially stretched UHMWPE, we were able to observe structural changes owing to the stretching consistent with shorter measured o-Ps lifetime and increased o-Ps intensity.

Nanoimprint lithography has been applied to the manufacture of microlenses, antireflection films, and biochips because of its cost reduction advantage. Previously, we demonstrated a gas-permeable template derived from a thermal cross-linkable cellulose derivative with methacrylate (HPC-MOI) that eliminated defects due to the concentration of acetone gas between the template and the imprint material. In this study, we prepared a thermoset cellulose derivative with acrylate as the gas-permeable template (HPC-AOI). The results of Raman spectroscopy and indentation test confirmed that HPC-AOI had a very high cross-linking density when heated for 10 min. The micrographs and three-dimensional (3D) image of the 5 µm line and space pattern in the UV cross-linked material containing a volatile solvent showed that void defects were removed and edges were sharper when the HPC-AOI template was utilized.