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Highlights: [•] Oxidative group profiling of small ancient cellulose fragments coated with beeswax. [•] The main mechanism of deterioration was identified for the first time. [•] Beeswax coated cellulose was purely hydrolytically damage, no oxidation. [•] Hydrolysis caused by microorganisms secreting cellulolytic enzymes. [ABSTRACT FROM AUTHOR]

Abstract: The reactivity towards cellulose of various volatile compounds commonly released by paper was studied. Sheets of Whatman No. 1 (W1) and No. 40 (W40) were exposed to various concentrations of these compounds in vapour phase ranging from 20 to 80 ppm in closed vessels for 52 days in controlled ambient conditions, after which they were hygrothermally aged. The measured properties of the paper were copper number, degree of polymerization, zero-span breaking length, pH and yellowness index. The results showed that hydrogen peroxide was the most aggressive among the volatile compounds tested as it severely degraded W1 cellulose. The exposure of W1 to formic acid led to significant degradation, designating this volatile organic compound (VOC) as the most reactive toward cellulose among the carboxyl and carbonyl functionalized VOCs tested. On the other hand, acetic acid was found comparatively less reactive. Nitrogen oxides, which were produced up to 3 ppm from a side-reaction of the carboxylic acids with the magnesium nitrate used to control the relative humidity in the closed vessels, appeared to contribute significantly to the degradation despite their low concentration. Antagonistic effects were evidenced in binary vapour mixtures where the presence of aldehydes (formaldehyde and acetaldehyde) counteracted substantially the degradation induced by the most reactive compounds. It was also shown that acetaldehyde, hexanal and furfural in individual exposures had little to no reactivity. Upon exposure to formaldehyde, the rate of glycosidic bond cleavage of cellulose induced by the ageing of W1 was significantly reduced. [Copyright &y& Elsevier]

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 by far less investigated and understood. A prominent example of moderately alkaline cellulosic material is deacidified book paper from libraries which had undergone a mass-deacidification treatment. We studied their aging behavior under accelerated conditions in comparison to non-deacidified duplicates in order to better understand how the alkaline reserve, which was introduced by the deacidification treatment, affects the stability of the books on the long run. GPC analysis of cellulose and determination of carbonyl functionalities were performed, which were critical parameters to achieve a deeper insight into hydrolytic and oxidative changes of cellulose structure upon deacidification treatment and subsequent aging. Also, model book papers impregnated with different amounts of alkaline reserve were used to support the findings from the original book samples. Hydrolytic degradation rates of the original book papers were significantly reduced after mass deacidification compared to the non-deacidified duplicates. The beneficial effect of mass deacidification on cellulose stability was found to be strongly related to the amount of alkaline reserve deposited, independent of varying parameters of book papers. Although some indication of alkali-induced β-elimination was found (a minor decrease of the along-chain carbonyl content in the original deacidified book papers during aging), it did not occur to an extent that significantly influenced the molar mass of cellulose. The beneficial effect of retarded hydrolytic degradation by mass deacidification thus clearly outweighed possible negative alkalinity effects of the deposited alkaline reserve. [ABSTRACT FROM AUTHOR]

Utility asset managers and engineers are concerned about the life and reliability of their power transformers which depends on the continued life of the paper insulation. The ageing rate of the paper is affected by water, oxygen and acids. Traditionally, the ageing rate of paper has been studied in sealed vessels however this approach does not allow the possibility to assess the affect of oxygen on paper with different water content. The ageing rate of paper has been studied for dry paper in air (excess oxygen). In these experiments we studied the ageing rate of Kraft and thermally upgraded Kraft paper in medium and high oxygen with varying water content. Furthermore, the oxygen content of the oil in sealed vessels is low which represents only sealed transformers. The ageing rate of the paper has not been determined for free breathing transformers with medium or high oxygen content and for different wetness of paper. In these ageing experiments the water and oxygen content was controlled using a special test rig to compare the ageing rate to previous work and to determine the ageing effect of paper by combining temperature, water content of paper and oxygen content of the oil. We found that the ageing rate of paper with the same water content increased with oxygen content in the oil. Hence, new life curves were developed based on the water content of the paper and the oxygen content of the oil. [ABSTRACT FROM PUBLISHER]

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 present study, the extent of β-elimination-type degradation reactions was investigated by comparing deacidified and non-deacidified counterparts, using deacidified library materials and identical issues of non-deacidified books from second-hand book shops. The study dealt with only naturally-aged papers focusing on investigation of immediate effects of mass deacidification rather than a long-term impact. Gel permeation chromatography coupled with carbonyl group labeling gave insight into cellulose chain cleavage as well as into the behavior of oxidized functionalities. Processes occurring under natural aging conditions were compared to those upon artificial oxidation of model pulps. Library books did not show a significant reduction in molecular weight after mass deacidification compared to the non-deacidified controls, which stands in contrast to oxidized model pulps. The models showed a more pronounced loss of molecular weight upon deacidification treatments. A decrease in carbonyl groups other than reducing ends was found to occur. Thus, oxidized functionalities were found to be reactive in mass-deacidification reactions; the different behavior was traced down to particular regions of oxidative damage along the cellulose chains. In general, β-elimination processes did not pose a large risk factor upon mass deacidification treatments of the naturally-aged library material tested. [ABSTRACT FROM AUTHOR]

Volatile organic compounds emitted from a several decade series of bound periodicals (1859-1939) printed on ground wood paper, as well as historical books dating from the 1500s to early 1800s made from cotton/linen rag, were studied using an improved headspace SPME/GC-MS method. The headspace over the naturally aging books, stored upright in glass chambers, was monitored over a 24-h period, enabling the identification of a wide range of organic compounds emanating from the whole of the book. The detection of particular straight chain aldehydes, as well as characteristic alcohols, alkenes and ketones is correlated with oxidative degradation of the C fatty acid constituency of paper. The relative importance of hydrolytic and oxidative chemistry involved in paper aging in books published between 1560 and 1939 was examined by comparing the relative abundances of furfural (FUR) a known cellulose hydrolysis product, and straight chain aldehydes (SCA) produced from the oxidation of fatty acids in paper. The relative abundance of furfural is shown to increase across the 379-year publication time span. A comparison of relative SCA peak areas across the series of books examined reveals that SCA emission is more important in the cotton/linen rag books than in the ground wood books. [ABSTRACT FROM AUTHOR]

Abstract: In libraries and archives some of the items which, upon ageing, have acidified considerably since their production are so brittle that they cannot be handled without risking loss of material. In contrast to current deacidification processes, aminoalkylakoxysilanes (AAAS) improve the mechanical properties of paper. A simple AAAS, aminopropylmethyldiethoxysilane (AMDES) was used as a model to better understand previous observations made on these systems (hydrolysis, condensation and possible reactions with the organic substrate). The evaluation of the mechanical properties of papers that were treated with AMDES showed that there was no formation of a polymer network on the fibres’ surface. However, treated papers not only exhibited a high alkaline reserve, but also a significant increase in both their tensile breaking length and their folding endurance. Treatment of hygrothermally aged papers with AMDES provided improved folding endurance as well as a good resistance to ageing. Various oxidation treatments of the model papers using sodium hypochlorite led to the conclusion that the nature of the oxidised groups formed on cellulose did not seem to play a significant role in the strengthening mechanism but rather that this effect of AMDES mainly arose from hydrogen bonding between the two molecules. [ABSTRACT FROM AUTHOR]

Oxidation ageing experiments on paper insulation and transformer oil have been performed using two different techniques. One is a traditional ageing study wherein degree of polymerization (DP) is measured after conditioning in sealed bottles containing paper submerged in oil, where the partial pressure of oxygen over the oil is varied. Paper is sampled at certain intervals during 8 months and DP-values are measured. The other study was carried out by means of a microcalorimeter; continuously measuring the heat flow from the paper-oil sample. We find that the degradation reaction rate is not linear with oxygen concentration and that the activation energy of oxidation is lower than what has earlier been found for hydrolysis. The microcalorimeter appears to mimic ageing characteristics for oxidation and can potentially be a useful tool for quick ageing investigations. [ABSTRACT FROM AUTHOR]

Abstract: Pigment-coated, surface-sized, and surface-sized copy papers were treated with conventional corona, experimental pilot-scale plasma and laboratory-scale plasma. All the treatments increased the surface energy and oxidized the surface. The changes in the surface chemistry depended on treatment time and composition of the substrate surface. It seems that plasma especially oxidizes the long polymer chains, such as surfactants and other paper chemicals, on the surface of the paper. The ToF-SIMS distribution maps indicated that the pilot-scale treatment led to an uneven CO+ group distribution, whereas laboratory scale treatment gave a more even distribution of CO+ groups. In addition to chemical changes, topographical changes due to plasma treatment were detected. The RMS roughness increased for pigment-coated paper, whereas plasma treatment induced small nodules between the paper pigment particles with pigmented and surface-sized paper. The increase in roughness was also found to increase the wettability. This serves as a demonstration of roughness-induced increase of surface energy of the samples. [Copyright &y& Elsevier]

The hygroexpansion of paper was significantly reduced, up to 28% lower amplitude of change when the paper was subjected to a change in relative humidity from 20 to 85% RH, by oxidation of the fibre wall. Never-dried bleached kraft fibres were oxidised with sodium periodate, which specifically oxidises the C2–C3 bond of 1,4-glucans so that the cellulose is partly converted into dialdehyde cellulose. Since both the dry and wet strength of laboratory sheets were significantly improved, the dry tensile strength increased from 24 kNm/kg up to 66 kNm/kg and the relative wet tensile strength increased from 1.5% up to 40%, it is suggested that the aldehydes form hemiacetal linkages within the fibre wall during the consolidation and drying of the sheets. The mechanical, hygroexpansive and moisture sorptive properties of the sheets made from the oxidised fibres were studied. The results showed that the main reason for the reduced hygroexpansion was a decrease in moisture sorptivity, i.e. when the sheets made of fibres with different degrees of cross-linking were subjected to the same change in relative humidity, the more cross-linked fibres showed a smaller change in moisture content. It was also shown that the hygroexpansion coefficient, i.e. the moisture-normalised dimensional change, was not significantly changed by the periodate oxidation, i.e. indicating that there are no improvement in dimensional stability if the paper is subjected to a specific amount of water. [ABSTRACT FROM AUTHOR]

This study attempts to evaluate the applicability of chemical oxidation processes to polish biologically treated effluent of a plant manufacturing hardboard from waste paper to comply with the discharge limit of 120 mg l-1 chemical oxygen demand (COD). In the first step, a chemically assisted settling was applied. The optimum results were obtained with alum plus lime with the alum dose of 200 mg l-1. In the second step, chemically assisted settling effluent was fed into an activated sludge system and over 80% COD removal was achieved. In the last step of the experimental study, a series of ozone oxidation and Fenton oxidation methods were tested to remove residual COD. Ozone oxidation provided 80% COD removal. An ozone dose of 40 mg min-1 with a reaction time of two hours was found to be optimum. Catalytic ozonation by using ferric iron, as well as high pH ozonation, Fenton process and H2O2/O3 oxidation did not prove to be more efficient than plain ozonation under these study conditions. [ABSTRACT FROM AUTHOR]

The radio frequency (RF) argon plasma induced surface modification of paper revealed novel surface characteristics and substantially changed surface topography. It was found that RF-argon glow discharge affects surface properties resulting in photo-degradation and chain-scission mechanism on paper network structure. High-power and extended treatment time caused increasing elemental carbon, while decreasing the oxygen concentration on paper surface. However, increased hydroxyls and the creation of new carbonyl functionalities were verified by trifluoroacetoanhydride and pentafluorophenylhydrazine in vapor-phase derivatization reactions. [ABSTRACT FROM AUTHOR]

Abstract: The role of transition metals in oxidative degradation of cellulose has been studied. Degradation experiments with model papers and studies of hydroxyl radical production in solution have been performed with Fe, Cu, Mn, Co, Cr, Ni, and Zn. Rates of production of hydroxyl radicals in solution have been estimated using the radical scavenger N,N′-(5-nitro-1,3-phenylene)bisglutaramide in the pH interval 7–9. Hydroxyl radical production during degradation of Cu-containing cellulose has been studied. To gain a better insight into chemistry behind degradation processes, chemiluminometric experiments were also performed. The experiments provide strong evidence that the role of transition metals during the oxidative degradation of cellulose is catalytic. A correlation between the behaviour of transition metals in solution and in paper was established at low contents of transition metal in paper. [Copyright &y& Elsevier]

The article focuses on the influence of light-induced oxidation process on the degradation reaction in paper. Oxidation by natural ageing is slow as compared to light-induced oxidation. Light-induced oxidation reactions help in predicting the lifespan of single paper sheets. Irradiation of groundwood paper block reveals the potential risk of its exposed to light.

Abstract: Characterization of oxidation products responsible for yellowing of paper through absorption and through emission is presented using independently UV–visible absorption spectrophotometry and microspectrofluorimetry to survey the thermal oxidation at 100°C and the photo-oxidation at λ ≥340nm and at 60°C of the three types of paper containing low amount of ligneous residues (SA papers) or not (WH and C papers). It was shown that due to secondary oxidation yellowing of product is favoured in the dark. It was shown that pre-photo-oxidation largely increased the yellowing in the dark. The effect of pre-photo-oxidation on yellowing through absorption and on yellowing through emission was shown to be different. [Copyright &y& Elsevier]

Besides major NADH-, succinate-, and other substrate oxidase reactions resulting in four-electron reduction of oxygen to water, the mitochondrial respiratory chain catalyzes one-electron reduction of oxygen to superoxide radicalfollowed by formation of hydrogen peroxide. In this paper the superoxide generation by Complex I in tightly coupled bovine heart submitochondrial particles is quantitatively characterized.The rate of superoxide formation during-controlled respiration with succinate depends linearly on oxygen concentration and contributes approximately 0.4% of the overall oxidase activity at saturating (0.25 mM) oxygen. The major part of one-electron oxygen reduction during succinate oxidation (~80%) proceeds via Complex I at the expense of its-dependent reduction (reverse electron transfer). At saturating NADH the rate offormation is substantially smaller than that with succinate as the substrate. In contrast to NADH oxidase,the rate-substrate concentration dependence for the superoxide production shows a maximum at low (~50 µM)concentrations of NADH. NAD+ and NADH inhibit the succinate-supported superoxide generation. Deactivation of Complex I results in almost complete loss of its NADH-ubiquinone reductase activity and in increase in NADH-dependent superoxide generation. A model is proposed according to which complex I has two redox active nucleotide binding sites.One site (F) serves as an entry for the NADH oxidation and the other one (R) serves as an exit during either the succinate-supported NAD+ reduction or superoxide generation or NADH-ferricyanide reductase reaction. [ABSTRACT FROM AUTHOR]

The oxidation reactions of cellulose involve the primary and secondary hydroxyl groups of the pyranose ring and result in carbonyl and carboxyl groups. This reaction can be accompanied by opening the pyranose ring. In any cases the glucosidic bond becomes weaker; the formation of carboxyl groups induces a depolymerisation, thus reducing the polymerisation degree and the physical and mechanical strength of the material. The conversion of 1,2-dihydroxyl groups to dialdehyde by periodate oxidation on cellulose based materials as textiles (flax and cotton) and paper with different composition and characteristics, has been studied. To investigate the cellulose behaviour at different level of oxidation, two different solutions of sodium methaperiodate were used: 0.1 and 0.4 M, for different times of treatment. The oxidised samples become “models” to investigate the different levels of degradation in real materials. Thermal analysis is convenient and reproducible, and is a useful method for characterising heterogeneous organic materials from plants. In this research we have examined the assignment of the exothermic transition in DSC analysis of paper, flax and cotton and its components in order to understand their thermal behaviour in more detail and to evaluate the effect of the oxidation treatment on the thermal behaviour. The aim of our work is to correlate the level of degradation of the oxidised samples with the natural ageing of the real cellulose based materials. The results obtained suggest information in the restoration and conservation field of cellulosic materials. [Copyright &y& Elsevier]

Maize starch was oxidized with sodium hypochlorite and hydrogen peroxide. Carboxyl content of oxidized starch were determined. Carboxyl content of starch oxidized with hydrogen peroxide is greater than that oxidized with hypochlorite. The maximum carboxyl content was obtained at pH 11 for 2 h by using hydrogen peroxide. On addition of oxidized starch to wood pulp shows great improvement in mechanical and physical properties of wood paper. Oxidized starch can be used as a good retention aid for kaolin. [ABSTRACT FROM AUTHOR]

The effects of moisture, oxygen, and acidity upon the aging of Kraft and thermally upgraded ("Insuldur®") papers have been studied in detail. The results for Kraft are consistent with the kinetic model and parameters proposed earlier by Emsley et al., and with the principle that moisture promotes acid-hydrolysis by causing carboxylic acids to dissociate. Moisture is released during the aging of Kraft and, hence, its aging is auto-acceleratory. In contrast, Insuldur consumed moisture under the same conditions, aged more slowly, and its aging was less accelerated by added moisture. 2-Furfuraldehyde (2FAL), which is a dehydration product of pentosans and, hence, an index of moisture production, is also released from Kraft during aging, but not from Insuldur. Acids are, however, produced from both types of paper. Theoretical explanations for these findings are proposed, and their practical implications for transformer maintenance are discussed. [ABSTRACT FROM AUTHOR]

Investigates the hypothesis that there is a symbiotic action between acidity and oxidation on the depolymerization of cellulose, the main component of paper. Functional groups formed after oxidation of cellulose with hypochlorite, depending on pH; Effect of acidity on the depolymerization process; Discussion on the degradation of cellulose oxidized by aqueous solutions of metaperiodate at different concentrations.

Presents a study which examined an oxidometry method which allows the separation of hydrolytic or direct chain cleavages from scissions made possible by oxidation in papers. Evaluation of the extent of oxidation; Effect of the method on cellulose paper; Conclusions.

The rusty-red, irregularly shaped areas known as foxing or fox spots are prevalent on rag paper used in books from the sixteenth to the nineteenth century. Foxing may vary in size from just visible spots to large areas covering most of a page, and in some cases the stain migrates through successive pages. The present study investigated the role of fungi in foxing, and the location and cause of the discoloration in these spots. Using light microscopy and staining with aqueous aniline blue, it was observed that the initial cause of the foxing was a group of separated conidia (spores) which had been deposited on the surface of the paper prior to printing and had germinated in situ during the slow drying of the paper. The colour in the foxed areas is due to an alkaline-soluble rusty-red material and an insoluble straw-coloured stain in the paper fibres. Observations of migrated stains support the theory that fox spots are part of three-dimensional stain structures which are generated in stacks of paper either during the manufacturing process or after binding. Papermakers' felts are suggested as the source of contamination, and autoxidation of lipids from the conidia is a possible cause of the discoloration of the fungal material and paper fibres. [ABSTRACT FROM AUTHOR]

Framed and glazed prints have been found to yellow rapidly when on exhibition. It was found that the frames all contained the fungicide thymol. Experimental work has shown that the discoloration is caused by photoxidation. The discoloration was present in the paper and in the polymethyl methacrylate glazing. Mass spectroscopy has revealed the presence of a polymer of thymol; there was no evidence for the expected oxidation products. [ABSTRACT FROM AUTHOR]