| Abstract: | SUMMARIES. The creation of sufficiently large alkaline reserves is, besides elimination of acidity, another im¬portant aim of any deacidification of groundwood papers. It is problematic reaching a required alkaline reserve of 2% because the amount of alkaline reserve retained in the paper is deter¬mined by the type of paper and its initial acidity. It is also difficult because the amount and con¬centration of the chosen deacidification agent necessary for both aims must be adjusted to take both into account. With a mass method this adjusting is almost impossible. The research re¬ported aimed at finding the relationship between the alkaline reserve measured as change of pa¬per weight before and after deacidification on one side, and by titration on the other
CONCLUSION. Pure cellulose paper Wl • It is relatively easy to determine precisely the preparation of AR in such a pa¬per and assign it to a certain MMMC concentration. For potentiometric de¬termination of AR it is necessary to titrate to pH 6.0 (range of AR1-3). In these conditions there is a good congruence between AR determination by weighing and by titration. • It is possible to prepare a large alkaline reserve. • The amount of titratable substances below pH 6 is small. Newsprints Nl and N2 • In modern newsprints it is possible to calculate relatively precisely the size of AR and prepare it by means of various MMMC concentrations if the pH in extracts is higher than pH 7.0. The analysis indicated a good congruence be¬tween ARg determined by weighing and AR1-3 determined by titration to pH 6.0. • At lower extract pH the end-of-titration in the range of AR1-3 is reached at lower pH and does not refer to real AR. • The amount of titratable substances below pH 6.0 is relatively large. • The method of determining ARg, i.e. by weighing, provides relatively accurate results. Historic newsprints C and H • It is relatively difficult to reach a desired amount of AR in these papers using preparations of the deacidification solution. • There is a big difference between AR1-3 stated by titration and ARg stated by weighing. • Even using high MMMC concentrations, the AR reached in these papers is only 1-2%. • The amount of substances able to be titrated below pH 6.0 or pH 5.0 is large. • Determination of AR1-3 by titration represents only 29%-34% of the capacity of acid-based systems in the papers referring to the true AR; it is just about 50% of the ARg. |
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