The efficacy of newsprint paper deacidification by carbonated magnesium propylate dissolved in heptafluoropropane
Institute of Polymer Materials, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 812 37 Bratislava, Slovak Republic
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Abstract: None of the existing methods conforms to the requirements of a genuinely “ideal” mass deacidification process. Beside the efficacy of deacidification processes, economic, safety and environmental risks are connected with the different systems.
The efficacy of stabilisation of highly lignified wood-containing paper by the carbonated magnesium propylate in the liquified gas of the 1,1,1,2,3,3,3-heptafluoropropane (HFC 227) was measured and compared with deacidification of the same paper by hexamethyldisiloxane, and air-water based deacidifying processes. The wood-containing paper test books were deacidified in Preservation Academy Leipzig, air-conditioned at the relative humidity RH = 50 %, and aged in sealed bags at 96±2°C.
The kinetics of folding endurance (), tensile strength (lt) were measured and the indexes of relative increase of the lifetime (S ), the folding endurance (S, t) and the tensile strength (Slt, t) were calculated. The process was evaluated through multifactorial evaluation according to requirements of the Consortium KnihaSK and the Library of Congress.
The deacidification by carbonated magnesium propylate dissolved in HFC 227 fulfilled neither the Consortium KnihaSK nor the Library of Congress requirement for the lifetime increase (S=1.3). It did not improve the mechanical permanence of the wood-containing paper (Sω, 15=1; Slt, 15
=1.15). The comparative evaluation proved the superiority of the HMDO as well as air-water based deacidifying systems over the HFC based system for the wood-containing paper, which is an important sort of the paper in archives and libraries.
Keywords: efficacy, deacidification, carbonated magnesium propylate, heptafluoropropane, comparison
Full paper in Portable Document Format: acs_0011.pdf
Acta Chimica Slovaca, Vol. 1, No. 1, 2008, pp. 124—133