Characterization of changes induced by ageing to the microstructure of pure cellulose paper by use of a gravimetric water vapour adsorption technique

Abstract

The changes induced to paper microstructure by accelerated ageing were studied using an automated gravimetric technique based on water vapour adsorption. The technique can be used especially in applications involving the adsorption and desorption of water, such as paper recycling, hornification, ageing and aqueous conservation treatments. The logistics for the calculation of the specific surface area of the examined samples are presented, and the f-plot technique was applied for the visualization and interpretation of the results. These indicated that ageing reduced the adsorption and the swelling capacity of the paper, resulting in a more compact structure, increasing crystallinity and promoting hornification.

Reconditioning acidic and artificially aged cellulose with alkaline nanoparticles: an NMR diffusometry study

“…As a result, sample A1 displays a significant decrease in the apparent diffusion coefficient (D 1 ) and confining size for water (d 1 ). The environmental conditions of the artificial aging, i.e., high temperature and relative humidity, promote the mobility of cellulose fragments and the cleavage of cellulose chains at random sites, which allows for a more compact arrangement of the fragmented cellulose molecules (Zervos 2007). Further depolymerization of cellulose following artificial aging is confirmed by S * values, which increase from 0.7 to 1.6, as reported in Table 1.…”

“…To this end, untreated, acidic and deacidified samples underwent a two-week aging at high temperature and relative humidity, which is commonly used to induce the depolymerization of cellulose. Since acidification and artificial aging trigger various processes that influence intra-and inter-chain interactions (Kato and Cameron 1999;Zervos 2007), the arrangement of cellulose might result rather modified. The resulting modifications in samples may allow to establish whether alkaline nanoparticles work as a successful conservation method even from the standpoint of cellulose arrangement.…”

Detection of acidic paper recovery after alkaline nanoparticle treatment by 2D NMR relaxometry

“…The strong environmental conditions of the artificial ageing are known to trigger the cleavage of cellulose chains at random sites (see S * values in Table 1) and, at the same time, to favour their mobility due to crosslinking or to the formation of irreversible intrafibre hydrogen bonding, any of which does not affect the DP. [38,39,51] All these phenomena, in particular the latter two, might allow for a more compact arrangement of the fragmented cellulose molecules, resulting in a reduction of the confining size for water and, in turn, of water mobility. This scenario is confirmed by water's confining size in R2 as highlighted by the diffraction dip reported in Figure 2, which returns d = 2.0 ± 0.1 μm.…”

“…As mentioned above, the hydrothermal treatment of paper induces the depolymerization of cellulose at random sites and triggers the mobility of cellulose chains, thus favouring a rearrangement in the fragmented cellulose molecules by crosslinking and intrafibre hydrogen bonding. [38,39,51] It is interesting to note that, in the case of acidic samples, the reduction of the average T2 values is drastic, which probably means that, in such samples, the formation of intramolecular and intermolecular bonds during ageing increases remarkably, especially after the first week. Indeed, as clearly shown in Table 1, DP values of A1 and A2 are almost equal, confirming that in samples A2, crosslinking is favoured with respect to depolymerization.…”

“…The untreated sample plays the role of the reference standard. Acidification and artificial ageing trigger various processes that influence intrachain and interchain interactions, [38,39] possibly inducing changes in the arrangement of cellulose and therefore on water relaxation characteristics. As a result, the study of relaxation modifications using NMR may provide critical information to establish whether alkaline nanoparticles work as an effective tool in hampering cellulose degradation also from the standpoint of cellulose network arrangement.…”