Enhancing capillary action of acidified paper to achieve uniform deacidification and long-lasting aging resistance

Abstract

Deacidification is a necessary and urgent means of protecting acidified paper documents. However, the contradiction between deacidification efficiency and uniformity in existing aqueous or organic phase deacidification methods has not been resolved yet, which is mainly attributed to the differences in capillary action of paper on solvents with different polarities. In this work, a strategy of two-phase deacidification was proposed to achieve efficient and uniform deacidification and long-lasting aging resistance. Impregnation of nano magnesium oxide organic dispersion of deacidified paper achieved efficient batch deacidification and sufficient alkali reserve. Using ultrasonic atomization of saturated calcium hydroxide aqueous solution, the penetration of alkaline substances into paper promoted uniform deacidification based on strong capillary action. Meanwhile, microstructural reinforcement of paper fibers was achieved based on the multiple interactions. This method can endow the treated paper with better thermal stability and long-lasting aging resistance. After artificial accelerated aging for 30 d, the treated paper samples still maintained the highest tensile index (18.46 Nm/g), folding endurance (8.5 times), tear index (3.95 mN·m2/g) and displayed negligible chromatic aberration (∆E = 2.46 ± 0.21). This method greatly extends the lifespan of acidified paper, which has significant value for the protection of paper documents.