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We have investigated the reactivities of various cellulases onribbon-type bacterial cellulose (BC I) and band-shaped bacterial cellulose (BCII) so as to clarify the properties of different cellulases. BC I waseffectively hydrolyzed by exo-type cellulases from different fungi from twicetofour times as much as BC II, but endo-type cellulases showed little differencein reactivity on those substrates...
Deterioration of historical papers is caused by several processes, such as acid hydrolysis or autoxidation due to the presence of metal ions contained in inks or pigments. Both processes can be studied by fluorescence labeling of carbonyl and carboxyl groups in combination with GPC-MALLS. This technique allows to determine not only the extent of hydrolysis, but also the concentration of oxidized functionalities...
In this paper we present a time-temperature superposition method for predicting the permanence of paper by extrapolating accelerated paper ageing data to ambient conditions. The presented method includes a test for the presence of shift factors to superpose all of the raw accelerated ageing data over the temperature range studied to obtain a master curve, a numerical fit of the master curve for producing...
During the operation of electrical equipments the compound 2-furfuraldehyde (2-FAL) and other related furanic substances are produced from the insulating paper degradation and can be detected in the mineral oil by high performance liquid chromatography (HPLC). Their concentration increase can be used to estimate the quality of the paper insulation inside the equipments. In this work colorimetric methodologies...
Cellulose in historic paper documents is often damaged by the writing media used, especially iron gall ink or copper pigments. Degradation induced by iron gall ink is suggested to be a synergistic process comprising both hydrolytic and oxidative reactions. These processes were studied on very low sample amounts according to the CCOA and FDAM method, i.e. by fluorescence labeling of carbonyl and carboxyl...
Recently, the existence of a relation between the rupture of 1,4-β-glycosidic bonds in the cellulose during thermal-ageing of paper/oil systems and the detection of methanol in the oil has been reported for the first time in this journal (Jalbert et al. 2007). The present study addresses the rate constants of the reaction for standard wood kraft papers, two immersed in inhibited naphthenic oil under...
We report on the accelerated ageing of cellulose based insulating paper by means of pulsed UV laser irradiation (λ = 248 nm) under various experimental conditions including paper composition, background gas (He, N2 and air) and moisture content of the paper. The temperature reached by the paper samples during their laser irradiation was monitored by means of real-time IR imaging. It is shown that...
Use of crude oil derivatives such as diesel and gasoline is becoming unsuitable due to their detriment to environment and to the increasing worldwide energy demand which is driving crude oil reservoirs towards exhaustion. Replacement of diesel and gasoline with biofuels (i.e. biodiesel and bioethanol, respectively) is very desirable. In fact, biofuels are not only environmentally sustainable, but...
As papers become acidic and brittle over time, libraries apply mass deacidification processes to their collections in order to neutralize acids and deposit an alkaline reserve in the paper. Books commonly treated by mass deacidification have undergone natural aging of up to 150 years. The risk of alkali-induced degradation of cellulosic material upon mass deacidification remains uncertain. In the...
Degradation of cellulose under alkaline conditions is involved either involuntarily or deliberately in many different cellulose processing steps, such as pulping, bleaching, or aging within the viscose process, and the underlying chemistry has been the topic of numerous studies. When it comes to aging under alkaline conditions—either natural or accelerated (artificial)—the degradation processes are...
Hanji paper, the paper material traditionally used in Korea, is in the focus of the present aging and mechanistic study. As raw materials and historic recipes for paper making are still available for Hanji today, specimen resembling historical material at the point of production can be prepared. While from that starting point, historical material had taken the path of natural aging, newly prepared...
To go further in our assessment of methanol for the monitoring of the cellulosic insulation condition in electrical transformers, two of the paper/oil systems [one comprising a standard wood Kraft paper and the other, a thermally-upgraded Kraft paper (TU paper)] discussed in Parts 1 and 2 (Gilbert et al. in Cellulose 16:327–338. doi: 10.1007/s10570-008-9261-1 , 2009; Cellulose 17:253–269. doi: 10...
The kinetics of oxygen delignification and cellulose degradation of a high kappa softwood Kraft pulp (kappa 65) are studied in a “flow-through” reactor where the pulp was held immobile within the reactor and a fresh oxygenated alkaline solution passes through the pulp mat at a set temperature. The feed solution maintains the alkali and dissolved oxygen concentration inside the pulp mat at nearly constant...
The life of an electrical transformer is mainly determined by that of its cellulosic solid insulation. The analysis of the chemical markers of cellulose degradation dissolved in oil is a simple and economical way to indirectly characterize the insulating paper. Methanol, a marker that is intimately linked to the rupturing of 1,4-β-glycosidic bonds of cellulose, has been observed together with ethanol...
This paper reports the temperature-dependence of methanol generation and the tensile index under ageing conditions for two paper/oil systems: one consisting of a standard wood Kraft paper and the other of a thermally-upgraded Kraft paper (TUK). A linear correlation between methanol and the tensile index for these paper/oil systems was observed in a previous study at 170 °C. In the current study, the...
Depolymerization of cellulose starting from an oxidized anhydroglucose unit through β-alkoxy-elimination, triggered by alkaline media, is one of the key reactions responsible for cellulose aging. This study investigates the detailed mechanisms for the chain cleavage by a combination of experimental and quantum chemical methods. Three model compounds for oxidized anhydroglucose units in cellulose were...
Herein, one-step conversion of cellulose dissolved in 1.75 mol L−1 NaOH/0.074 mol L−1 ZnO aqueous solution to organic acids was realized through a hydrothermal degradation without heterogeneous catalyst. The effects of solvent, the concentrations of NaOH and ZnO, O2 pressure, temperature and the reaction time on the yield of organic acids were investigated and discussed. The components of the degraded...
Cellulose is often described as a mixture of crystalline and amorphous material. A large part of the general understanding of the chemical, biochemical and physical properties of cellulosic materials is thought to depend on the consequences of the ratio of these components. For example, amorphous materials are said to be more reactive and have less tensile strength but comprehensive understanding...
Although cellulose is the oldest macromolecule we have known, its intrinsic properties are still not well understood because of the lack of suitable solvents. The recent development of ionic liquids enables preparation of cellulose solutions in which cellulose molecules are supposed to be dispersed molecularly. Conventionally a semi-flexible-chain model or a worm-like chain model has been applied...
Cellulose degradation is less known in the Ascomycota phylum, but it is important to recognize it because this process influences the most important biochemical cycle: the carbon cycle. Cellulose degradation is carried out by a complex enzyme: cellulase. Petriella setifera has recently been recognized as a producer of cellulolytic enzymes. In this work, it was shown, that the activity of cellulose-degrading...
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