LIFE PREDICTION OF LOW-DENSITY POLYETHYLENE USED FOR OUTDOOR TELECOMMUNICATIONS CABLE SHEATHING BY OUTDOOR EXPOSURE TEST AND ACCELERATED TEST

摘要

An outdoor exposure test and an accelerated aging test using the carbon arc sunshine weather meter were conducted to predict the life of low-density polyethylene (LDPE) used for outdoor telecommunications cable sheathing. The carbon black content of LDPE used for testing was lower than that of he actual cable sheath to accelerate the deteriortion. Outdoor exposure tests were performed in Kitami in Hokkaido, Musashino in Tokyo, and Sashiki in Okinawa for 10 years. The decreasing rates of the strengthes for the materials during the outdoor exposure test were determined by correcting the sunshine time with the sunshine efficiency as a function of the latitude. The rete of degradation in the accelerated test was about twice as high as that in the outdoor exposure test based on the corrected sunshine time, and about thirteen times as high as that in the outdoor exposure test based on the real exposure time.