Hydroxypropyl Cellulose and Gum Arabic Loaded with Silver Nanoparticles for the Consolidation Process of Papyrus Sheets

Various weakened archaeological papyrus manuscripts exist in excavations, museums, libraries, and storehouses. The preservation of brittle archaeological papyrus manuscripts remains a challenge due to environmental factors and the fragility of the material. Therefore, the present study aimed to evaluate new nanocomposites for the consolidation process of brittle archaeological papyrus manuscripts. Two nanocomposites containing hydroxypropyl cellulose (HPC) loaded with silver nanoparticles (AgNPs) and gum Arabic loaded with silver nanoparticles (AgNPs) at 0.5% and 1% (by weight) have been prepared. The prepared nanocomposites and individual AgNPs have been characterized with a transmission electron microscope (TEM). Accelerated-aged papyrus strips have been treated with the prepared nanocomposites using a spraying technique. After application of consolidation materials, the treated samples were subjected to accelerated aging at 80 °C and RH 65%. Different analytical techniques, including investigation with a scanning electron microscope (SEM), measurement of color change, mechanical properties (tensile strength and elongation), pH, and Attenuated Total Reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) analysis, have been used in the evaluation process. The results of TEM showed a predominance of spherical-shaped nanoparticles, either for individual AgNPs or nanocomposites, with an average size ranging from 10–22 nm for individual AgNPs, 19.5–30.0 nm for AgNPs/HPC, and 9.0–26.9 nm for AgNPs/gum Arabic nanocomposites. The significance of these size ranges for conservation applications is their ability to deep penetration on cells of organic objects; furthermore, spherical-shaped nanoparticles allow the presence of nanoparticles without destruction in the structure of the papyrus parenchyma cells because it has non-sharp edges. The investigation by SEM showed good penetration of AgNPs and HPC at 1% inside papyrus cells. The results of color change showed that there was no significant color change after treatment and aging, especially in treated samples with AgNPs/HPC nanocomposite at 1%. The measurement of pH showed a noticeable reduction in acidity for all treated and aged-treated samples. The results of ATR-FTIR analysis revealed that treatment with AgNPs and HPC at different concentrations led to an increase in the cellulose crystallization bands compared to the aged, untreated sample. The mechanical property results showed that the 1% AgNPs/HPC nanocomposite improved the treated samples' tensile strength and elongation both before and after the aging process.