Stability of lignocellulosic papers strengthened and deacidified with aminoalkylalkoxysilanes

Abstract The durability of paper documents treated with aminoalkylalkoxysilane copolymer (co-AAAS) flexible networks, as deacidifying and strengthenening agents, was studied. To this end, a 1922 lignocellulosic newsprint paper was treated with co-AAASs and characterized. Physico-chemical properties such as pH, chromatism, opacity and mechanical strength were measured shortly upon treatment and several years after. In order to better understand the role of the initial degradation state of the paper and the impact of its constituents other than cellulose (lignin, alum-rosin sizing) on the treatment efficiency, several laboratory papers were added as models. It was shown that alum-rosin sizing contributed to a decrease in pH of the most degraded treated paper over the monitoring time, whereas the strengthening effect was mostly affected by the presence of lignin. In particular, for most papers, after several years, the gain in folding endurance was the lowest in the lignin-rich ones. The breaking length of all the papers increased post-treatment and over time, independently of the paper constituents. This was attributed to the slowly progressing aminoalkylalkoxysilanes polycondensation, on the scale of years, as evidenced by Cross Polarisation – Mass Angle Spinning 29Si solid-state Nuclear Magnetic Resonance.