Le projet PAPYLUM : la chimiluminescence: un nouvel outil...

Oharrak: Texto en francés, resumen en inglés
Sumario: In frame of European project Papylum a consortium of researchers has gathered to study oxidative degradation of paper. This topic has recently attracted considerable interest due to its importance in the optimisation of water-based paper deacidification treatments, both manually and on mass-scale. In order to understand paper oxidation better, a wide variety of analytical techniques, including measurements of chemiluminescence is weak light emission occurring during oxidation of organic materials. The intensity of chemiluminescence is closely linked with the rate of the chemical process leading to it. The technique has been used in polymer degradation research for several decades, mainly in experimental laboratories. However, it is fairly novel in the field of paper degradation and a new instrument had to be constructed allowing non-dsestructive sampling and experiments in atmosphere of well-defined humidity. Photodegradation studies, relevant for frequently exhibited materials, showed that humidity during light exposure increases the rate of degradation. Due to this, it has to be well controlled during photoageing experiments. Due to the extensive degradation which occurs in the darkness after irradiation with light, an imporved protocol for photoageing experiments is proposed. Among other important results of practical interest is the finding that water affects the rate of oxidative degradation of cellulosic materials to a prominent extent. Accelerated ageing studies indicate that by lowering the RH during long-term storage of deacidified material, the rate of degradation may be reduced by up to 10 times. Extensive research further showed that a room temperature, real rosin-sized paper samples degrade 2-60-times more slowly after aqueous deacidification. The factor of stabilisation depends on a variety of parameters, also on the alkali used, Mg(HCO3)2 usually performing better. The use of antioxidants of the halide type may further decrease the rate of degradation, again at room temperature, for 10-to 100-times, while discolouration was apparently not affected. The knowledge was summarised in the book Ageing and Stabilisation of Paper, available from http://papylum.uni-lj.si