Characterization of UVA-irradiated wheat paste and paste-coated paper

Abstract

Starch paste has been the main adhesive of choice for paper conservation until now. Studies evaluating the properties of paste-coated paper under UVA irradiation conditions are limited but necessary to enable conservators for a proper choice of materials in terms of durability. In this paper, SEM, FTIR, Raman, and measurements of mechanical properties were used to investigate the aging features of UVA-irradiated paste-coated paper. The increased macro and micro physical and chemical changes with increasing UVA exposure time indicated the degradation of paste and paper polymers. The pH and spectroscopic analyses indicated that the carboxyl groups, which led to the acidity of the sample, were slowly produced with increasing irradiation, and the pH of the paste was lower than that of the paper samples when exposed for the same amount of time. The change in crystallinity also affected the degradation rate of paste-coated papers. SEM observations showed that the paste was destroyed more easily than the paper fibers, a higher concentration of paste caused the paper fibers to break, and a lower concentration of paste damaged both the paste and paper fibers. The present study suggests that an appropriate concentration of paste coated on the paper surface could improve the irradiation stability of paper samples for paste-restored paper artifacts.