Nishimura Hiroyuki
# 2012 Barcelona
The effect of antioxidants of polyethylene of raised temperature resistance (PE-RT) pipes for a long lifetime for hot water supply and for space heating was evaluated in this paper. Some polyethylene specimens mixed with different amount of antioxidants such as hindered phenol and hindered amine were prepared by injection molding. The specimens were immersed in hot water and exposed to hot air at the temperature of 60, 80, 98(100), and 120 °C for 10000 hours or more. After that, the tensile test and the thermal analysis were carried out. The tensile strength of specimens immersed and exposed at 98 and 120 °C was higher than that of the blank specimens because the crystallization of specimens has progressed. There was a great variability among the elongation at breakage. As a result of the thermal analysis, it was found that resin degradation was not advance for 5000 hours because there was no change in the melting point. As a result of the Oxidation Induction Time (OIT) measurements, it was found that antioxidants were remained in a resin. From the longterm degradation test of PE-RT mixed with different amount of antioxidants, it was found that the original resin of PE-RT degraded for 7000 hours or more because there was almost no antioxidant.
Related papers
Author(s) : Hirofumi Kyutoku, Kazuhisa Igawa, Hidekazu Honma, Sakiko Fukunishi, Hiroyuki Nishimura
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Author(s) : Yuichiro Goto, Hiroyuki Nishimura
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Author(s) : Takehiro Fujii, Hideo Hirabayashi, Kazushi Yamada, Hiroyuki Nishimura
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Author(s) : Kazuhisa Igawa, Yuji Higuchi, Akio Kamatani, Kazushi Yamada, Hiroyuki Nishimura
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Author(s) : Nishimura, Kawaguchi
The required performance of polyethylene pipes for gas distribution is firstly described. As an evaluation method for slow crack growth, the relation between crack growth length and time under test was obtained to investigate the stress crack resistance of polyethylene pipes for gas distribution after conducting...
Author(s) : Nishimura, Inoue, Inoue, Tani, Higuchi
Electrofusion (EF) joints have been widely used as easy-to-fuse and high-quality joints for joining polyethylene (PE) pipes. When we introduced EF joints 150 mm or more in diameter, an electrofusion simulation program was concurrently developed to reduce time for design and experimental works. It was verified that the...
Author(s) : Yoshida, Kitaoka, Nishimura
Because dirt ( sand, mud, etc. ) on the fusion interface causes a decrease in the strength of fusion joints, it is necessary to scrape and clean the pipe surface before fusion jointing. We have determined the degree of dirt that causes a decrease in the strength of fusion joints by experiments on peeling off at the...
Author(s) : Nishimura, Macba, Ishikawa, Ueda
In the Great Hanshin-Awaji Earthquake, dthough leak and cracking occurred mainly in joints of small-diameter steel pipes with screwed joints, no damage occurred to polyethylene pipes. To secure aseis~uicresistance of gas pipeline, polyethylene pipes are expected to come into wider use i n the future. To deternune the...
Author(s) : Higuchi, Nishimura, Tamamura, Harada
To estimate the long-term performance of polyethylene pipe, molecular structure of polyethylene resin were analyzed and the long-term performance test were done. By linking the molecular structure of the resin to the results of long-term performance tests such as tensile creep tests and tensile fatigue tests, it...
Author(s) : Kitao, Hiarse, Nishimura, Inouge, Ishikawa, Otani, Miyasa, Kato
In this paper, the behavior of rapid crack propagation in gaspressurized polyethylene pipes was analyzed using the method in which two characteristic curves, i.e., the crack velocity and the gas decompression velocity, were compared. The crack velocity of 216mm outer diameter SDR13.5 medium density polyethylene...
Author(s) : Nishimura, Suyama, Inoue, Higuchi
This paper describes an evaluatio~i metl~od for elearofusion joint strer~gtl~ and a basic co~~cept for determination of suitable fusion jointing col~ditio~~s. Firstly, the concept for estimating electrofusion joint strength is indicated. As an experimental result, it was found that the optimum fusion range lay...
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