Cellulose Nanofibril-Stabilized Porous CaCO3 Synergistic System for Simultaneous Deacidification and Reinforcement of
Rui Hou1, Liqin Liu1, Yinying Long1
1State Key Laboratory of Bio-based Fiber Materials, Tianjin Key Laboratory of Pulp and Paper, China Light Industry Key Laboratory of Papermaking and Biorefinery, China Textile Industry Key Laboratory of High-Performance Fibers Wet-Laid Nonwoven Materials, Tianjin University of Science and Technology, 29 13th Street, TEDA, Tianjin 300457, P. R. China.
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The preservation of aging paper archives is critically challenged by the synergistic deterioration from acid hydrolysis and mechanical weakening. Traditional approaches often address deacidification or mechanical reinforcement independently, failing to reconcile the critical need for simultaneous pH neutralization and structural restoration. This study successfully overcomes the limitation of conventional single-function treatments through the rational design of a synergistic dual-function preservation system that integrates porous calcium carbonate (P-CaCO3) and cellulose nanofibrils (CNFs). The P-CaCO3 component, synthesized via a controlled process using sodium dodecyl sulfate (SDS) and polyvinylpyrrolidone (PVP) as pore-regulating agents, functions as an efficient alkaline reservoir for acid neutralization. Simultaneously, CNF serves a dual role: as a dispersant that stabilizes the P-CaCO3 suspension and promotes uniform distribution and as a reinforcing agent that enhances the mechanical integrity of the aging paper matrix. We hypothesize that this synergistic system achieves simultaneous deacidification and reinforcement in a single treatment. When this system was applied to acidified aging paper samples, it achieved a balanced enhancement of both alkaline reserve capacity and mechanical properties under optimized conditions (0.4% CNF suspension and 1% PCCs/CNF suspension), during which, the treated aging paper achieved a 22.45% increase in tensile strength, 38.42% increase in burst strength, and 17.09% increase in tear strength, alongside a pH elevation from 5.82 to 8.28 and an alkaline reserve of 305 mmol/kg. This study establishes a novel, practical approach for the long-term preventive conservation of aging paper-based cultural heritage, directly addressing the dual challenges of acid degradation and mechanical weakening in aged documents.
