Paper aging

Many aldehydes are particularly fragrant. A number of flowers, for example, owe their pleasant odor to the presence of simple aldehydes. The smells of lemons, cinnamon, and almonds are due to the aldehydes citral, cinnamalde-hyde, and benzaldehyde, respectively. The structures of these three aldehydes are shown in Figure 12.21. The aldehyde vanillin, introduced at the beginning of this chapter, is the key flavoring molecule derived from the vanilla orchid. You may have noticed that vanilla seed pods and vanilla extract are fairly expensive. Imitation vanilla flavoring is less expensive because it is merely a solution of the compound vanillin, which is economically synthesized from the waste chemicals of the wood pulp industry. Imitation vanilla does not taste the same as natural vanilla extract, however, because in addition to vanillin many other flavorful molecules contribute to the complex taste of natural vanilla. Many books made in the days before acid-free paper smell of vanilla because of the vanillin formed and released as the paper ages, a process that is accelerated by the acids the paper contains. 

Effect of relative humidity on brightness of Foldur Kraft paper aged aa sheets and books at 90 5 ... 

Absorption coefficient description, 82 physical interpretation, 84 Accelerated aging of paper, effect of variations in relative humidity, 63-78 Acid degradation, effective means of book protection, 23-24 Acid formation in paper aging characteristics, 16 chief source, 16... 

Total US production of paper in 2005 was 37.6 million metric tons, and production of paperboard was 45.7 million tons at operating rates of 92% and 97% respectively. Production data and projections are analyzed by RISI,1 and periodic updates on industry issues, grade profiles and production statistics are published in Pulp and Paper, Paper Age, Pulp and Paper International and other trade journals. The US paper industry reuses more than 51% of the product it produces with an ultimate goal of 55%.2... 

Since low pH makes paper age rapidly, neutralizing and even alkalizing it should improve permanence. This has proved to be the case. 

Fold Loss Rate. A direct way of evaluating the effect of the morpholine process on the stabilization of paper is to measure the rate at which its folding endurance deteriorates before and after treatment. Figure 4 typifies the effect. The two lines are for the same paper aged in a dry oven at 100°C the line with the lesser slope reflects morpholine-treated... 

A recently published study concerned with the influence of oxygen on paper aging concluded that the total rate of degradation may be expressed as the sum of two general types of degradation processes an... 

As acid paper ages, the amorphous regions of the cellulose fiber that are plasticized by water and/or humectant tend to disappear. The sorbi-tol/Kymene treatment becomes ineffective with degraded paper. This suggests that somewhat the same effect would be observed between new and degraded papers when humidified. Adrian Sclawy of the Library of Congress Preservation Research and Testing Office, carried out the experiments on humidification which are reported in Chapter 16 of this volume. 

The data for the JCPA-60 paper aged fourteen and twenty-one days show that for the 20% -80% relative humidity range, the paper was of low strength. However, the highest folding endurance values were between 50% and 60% relative humidity. 

The Allied Superior paper aged seven days at 20% relative humidity was categorized as moderate strength. At 50% relative humidity, the folding endurance had more than doubled and the paper could be reclassified as high strength. 

Note Papers aged in dry oven were preaged at 100 °C for 14 h papers aged in humid oven were preaged at 90 °C and 50% rh for 7 h. 

Barrow (see above) used ageing in an oven for 72 hours at 100°C to replicate the effects of natural ageing of paper for 25 years. Nowadays, this assumption is still used, but regarded as simplistic and not applicable to all types of paper. Many laboratories prefer to perform their paper ageing in an oven at a controlled relative humidity and at a lower temperature. There is no consensus, but a... 

Like inks, paper ages in predictable ways. The time frame of ttiat decay depends on many factors. Ink aging and dating were discussed in tire previous... 

The chain deterioration of cellulose during paper aging is irreversible and cannot be cancelled. A renevdng of the fibers is not possible but there are possibilities to stabilize brittle paper and the following measures are worthy of consideration ... 

Berube, R.R, 1991, "Chemically Structured Coating Pigments Improve Paper Appearance and Performance", Paper Age, May, pp 16-18, 40. 

O Brien, J. 1994, "Second Generation ATH Pigment Improves Coating Formulations", Paper Age, Oct, pp 20,21. 

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