A Quantitative Measure Of Borane Tert-Butylamine Complex Effectiveness in Carbonyl Reduction of Aged Papers
| Main Authors: | , , |
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| Format: | Article |
| Language: | English Slovak |
| ISSN: | 0034-5806 |
| Online Access: | http://www.viks.sk/chk/res_1_99_22_29.doc |
| Abstract: | SUMMARIES. The goal of our experimental work is to provide a simple method for qualitative and quantitative determination of carbonyl groups, in order to evaluate when a reduction treatment is a primary need in a restoration procedure, and to test the effectiveness of borane tert-butylamine complex (TBAB) over time. Experimental data show that TBAB has an effectiveness of 50 to 80% in the reduction of oxidized functions. The modified method of Szablocs gave reproducible results and the test can also be simply applied in a qualitative manner as a micro destructive probe CONCLUSION. In Whatman untreated papers the plot of total carbonyl groups vs. days of ageing shows only a little increase even after 28 days: the rate of carbonyl formation is a constant over ageing time, the prevailing degradation mechanism is the scission of the glycosidic bond. The total carbonyl groups formation in KlC-oxidized and KlO-oxidized-TBAB reduced samples follow the same law. KIO4-oxidized papers, after a rapid increase in total carbonyl groups, reach a limit value of ca. 9 m.moles per 100 g of paper. The prevailing degradation mechanism during the ageing is the formation of oxidized functions on the an-hydroglucose ring. KIO4-oxidized TBAB-reduced papers show an initial amount of carbonyl groups similar to untreated paper; after several days of ageing the number of carbonyl groups increase, following a sigmoidal shape function, but the maximum value recorded after 28 days of ageing is 2/3 with respect to the corresponding oxidized-unreduced sample. We can conclude that in all the cases the presence of oxidized groups, not completely reduced, facilitate further oxidation. We also increased the duration of the treatment by immersion in TBAB solution for a longer time, but the measurements of the number of carbonyl for samples reduced either for one or five hours remain almost the same. On the contrary, as previously reported1, in case of ancient papers a longer immersion in TBAB is a good option to increase the effectiveness of the reducing treatment. It could also be noted that the paper will not be damaged even after a very long immersion. This is probably due to the pH 8.50 - slightly alkaline - of a 0.2 M solution of TBAB.In conclusion, all experimental data show that the reduction treatment of oxidized papers, followed by ageing (simulating the ageing of a restored ancient paper), offers a certain level of protection compared to the oxidized paper. Obviously, TBAB is not able to impede further and intrinsic oxidation of paper, but the initial low amount of carbonyl groups retards the oxidation process. The treatment of oxidized aged papers shows an effectiveness of 50 to 80% in the reduction of oxidized functional groups.The method used for detection of carbonyl content can also be simply applied in a qualitative manner as a micro destructive probe. A very little amount of paper could be treated with TTC and KOH at a hot temperature. The more intense the red colour appears, the more the paper is oxidized. Unoxidized papers show a pale pink colour, due to the reaction of the carbonyl terminal groups present in the cellulose molecules.Further development of our work will involve die use of different reducing products, in order to find new applications, especially in non aqueous solutions |
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| ISSN: | 0034-5806 |
