The efficacy of newsprint paper deacidification by carbonated magnesium propylate dissolved in heptafluoropropane

Silvia Holúbková ^*, Michal Jablonský

Institute of Polymer Materials, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 812 37 Bratislava, Slovak Republic

E-mail: ^* silvia.holubkova@stuba.sk

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 (l_t) were measured and the indexes of relative increase of the lifetime (S_{ }), the folding endurance (S_{, t}) and the tensile strength (S_{lt, t}) were calculated. The process was evaluated through multifactorial evaluation according to requirements of the Consortium Kniha^SK and the Library of Congress.
The deacidification by carbonated magnesium propylate dissolved in HFC 227 fulfilled neither the Consortium Kniha^SK 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 (S_{ω, 15}=1; S_{lt, 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.}