| 摘要 |
PROBLEM TO BE SOLVED: To provide a method by which the durability evaluation of a gas pipe made of a polyethylene resin and the quality judgement of a polyethylene resin for gas pipe can be executed rapidly. SOLUTION: In this evaluation method, the durability of a pipe is judged good in the case where the condition shown by (1) is fulfilled by a polyethylene resin composing a pipe, and besides, it is judged better in the case where the condition shown by (2) is fulfilled additionally. (1) A temperature dependency curve, obtained by measuring temperature dependency of sound wave propagation characteristics from room temperature to a temperature of perfect fluidization, has a sub-peak other than a main absorption peak caused by fusion or solidification of the whole. (2) The curve has two or more sub-peaks. |
