Res. Chem. Intermed.
, Vol. 31, No. 1–3, pp. 19–24 (2005)
Also available online - www.vsppub.com
The local reaction processes of polyethylene irradiated
with heavy ion-beam
and TOSHITAKA OKA
Advanced Research Institute for Science and Engineering, Waseda University 3-4-1 Okubo,
Shinjuku, Tokyo 169-8555, Japan
Received 10 February 2004; accepted 28 February 2004
Abstract—The local reaction induced in the track for low-density polyethylene irradiated with ion-
beam was investigated. The transformations of the chemical structure induced by irradiation are on
trans-vinylene, end-vinyl, vinylidine and the cross-link. The different reaction processes are induced
in the micro-region of the track. These processes depend on the stopping power. In the region of
larger stopping power, the rate of the process, which produces the end-vinyl, increases and that of the
trans-vinylene decreases. These results suggest that the main chain scission of the polyethylene can
be induced by very large energy deposition in the micro-region.
Keywords: Polyethylene; ion-beam irradiation; structure transformation; chain scission.
We have investigated the local transformation of the chemical structure induced in
polymers by irradiation with various ion-beams [1–6]. In these studies, we have
reported that if the sample is thick enough to stop an injected ion, the distribution
of the local transformations along the pathway of the ion should follow the Bragg
curve. In order to discuss the stopping power (energy deposited per unit distance in
a material: eV/µm) effect for polymers on ion-beam irradiation, it is very important
to ﬁnd out the relationship between the transformation yield and the stopping power
in the local region. One of the difﬁculties to analysis the local transformations along
the ion pathway is that some complicated chemical reactions are induced locally.
These local transformations may depend on the stopping power, which changes so
much around the Bragg peak.
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