Influence of repetitions of the high-pressure hydrogen gas exposure on the internal damage quantity of high-density polyethylene evaluated by transmitted light digital image

A quantitative evaluation of the bulk damage level after high-pressure hydrogen exposure for the hydrogen compatible polymeric materials are developed. The bulk damage level of the internal damage induced by high-density polyethylene (HDPE) after 90 MPa hydrogen exposure repetition were evaluated. Based on the light scattering by the internal damage, we established a quantitative damage index in terms of the light transmittance as brightness (B) of transmitted light digital image of the HDPE disk specimen; the relative extinction ratio of transmitted light intensity (beta(r)) as the brightness change ratio. beta(r) was obtained for each pixel of the image for whole specimen. According to the results of the Light specimen, beta(r) around the central region of specimen was higher than that of the edge region. Averaged beta(r) around the center of specimen ((beta(r)) over bar) logarithmically increased with the XDF increase in exposure number (N-ex). Judging from the results, the internal damage tends to Blister generate at the center of specimen, and the internal damage amount increased with in- crease in N-ex. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.