Hydrogen release from irradiated elastomers measured by Nuclear Reaction Analysis

(1) Institute for Electronic Materials Technology,National Centre for Nuclear Research
(2) Institute for Engineering of Polymer Materials & Dyes, Division of Elastomers & Rubber Technology
(3) Technical University of Lodz, Institute of Polymer & Dye Technology
(4) Institut of Ion Beam Physics and Materials Research, Helmholtz Zentrum Dresden Rossendorf
(5) Institute for Electronic Materials Technology

Advanced elastomers used in sealings of mobile connections must respond to numerous requirements: ability to work in wide temperature range, resistance to various fluids, ageing and oxidation. Several materials were developed to answer these needs. A common feature of these materials is a relatively high friction coefficient leading to increased wear rate and temperature rise in the contact area. Recently ion irradiation has been successively used to reduce friction and wear without affecting bulk properties of elastomers. Irradiation with ions leads to shrinking and smoothening of the surface layer, what suggests, that the effects obtained may be related to the hydrogen release from the surface layer. A detailed analysis of hydrogen concentration in irradiated samples is thus required to confirm or reject this assumption. Main experimental problem related to hydrogen measurements is a high susceptibility of organic materials to decompose under an ion beam. This excludes such methods as ERDA, as heavy ions lead to a very fast deterioration of the elastomers. The paper describes the experiments performed by using Nuclear Reaction Analysis (namely 15N(1H, αγ)12C reaction induced by 15N ions at 6.385 MeV) to measure the amount of hydrogen atoms in several irradiated elastomers. Huge advantage of this reaction is a very low irradiation fluence needed to collect a decent spectrum. A massive loss of hydrogen has been successfully detected and the results compared to elastic and inelastic energy losses. The analysis points to the decisive role of ionization processes in hydrogen release. Beneficial effects of ion irradiation on functional properties of irradiated elastomers will also be discussed.