Res. Chem. Intermed.
, Vol. 31, No. 7–8, pp. 661–666 (2005)
Also available online - www.vsppub.com
Long-term degradation of chemical structures
and mechanical properties in polyethylene induced
by ion-beam irradiation
and YOSHIMASA HAMA
Advanced Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo,
Shinjuku, Tokyo, 169-8555, Japan
Received 31 March 2004; accepted 22 June 2004
Abstract—The long-term oxidative degradation of chemical structures and the mechanical properties
in different polyethylenes induced by ion-beam irradiation were investigated. They were measured
along the ion trace when the samples were stored in the atmosphere for a very long time. The
hydroperoxide group is very important in the degradation process. These degradation processes are
attributed to the mobility of oxygen molecule due to the density and the crystallinity of polyethylene.
Keywords: Long-term oxidative degeneration; ion-beam irradiation; polyethylene.
We have investigated the relationship between the depth proﬁle of the local
transformations and the mechanical properties for polyethylene irradiated with
various ion-beams [1, 2]. These results give very important information on the
distribution of mechanical properties in the bulk on ion-beam irradiation and on the
long-term oxidative degradation in high-density polyethylene.
In this work, we investigated the long-term oxidative degradation of chemical
structures and the mechanical properties in different polyethylenes induced by ion-
beam irradiation. We measured the changes in the chemical structure and the
mechanical properties along the ion trace for polyethylene when the samples were
stored for very long time. It is well-known that the hydroperoxide group is very
important for the degradation. We discuss the stabilization of radicals, the density
and the crystallinity of polyethylene, the mobility of oxygen and the ﬂexibility of
the molecular chain to analyze the inﬂuence of the hydroperoxide group.
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