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The sustainable, efficient use of renewable bio-based additives in the production of various materials fits well into the concept of sustainability. Here, the concept of coaggregation of mineral filler particles and starch granules for improving filler-fiber interaction in paper-based cellulosic networks is presented. Coaggregation of precipitated calcium carbonate filler particles and uncooked, unmodified corn starch granules by cationic polyacrylamide (a cationic high molecular weight polymer flocculant) in combination with bentonite (an anionic microparticle) prior to addition to cellulosic fiber slurry delivered enhanced filler bondability with cellulosic fibers. For instance, under the conditions studied, preaggregation resulted in an increase in filler bondability factor from 9.24 to 15.21 at starch dosage of 1% (on the basis of the dry weight of papermaking stock). The swelling and gelatinization of the starch granules in starch-filler preaggregates or hybrids enabled the "bridging" of the gaps in cellulosic networks, leading to structural consolidation and strength enhancement., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Four residues generated in a Kraft, pulp and paper plant, were characterized by X-ray fluorescence spectroscopy (XFA), powder X-ray diffraction (XRD), thermogravimmetric analysis (TG) and Fourier transform infrared spectroscopy (FTIR). A quantitative phase composition model, that accounts for the observed data and for the physico-chemical conditions of formation, was postulated for each material. Emphasis was given on the identification of the mineral components of each material. The green liquor dregs and the lime mud contain Calcite and Gipsite. The slaker grits contains Calcite, Portlandite, Pirssonite, Larnite and Brucite. The Calcite phase, present in the dregs and in the lime mud, has small amounts of magnesium replacing calcium. The wood ash contains Quartz as the major crystalline mineral phase.

Abstract An experimental study of the inception of the first‐mode negative streamer at liquid/solid interfaces is presented in this article. The study is performed with a point‐plane configuration under square high voltage pulses. The electrode configuration is immersed in mineral oil and the liquid/solid interface is assembled in contact with the point electrode or in its vicinity. Four polymers and two impregnated papers have been tested as solids of the liquid/solid interface. Thus, it is possible to compare the influence of different parameter of the solid and the interface on the streamer inception. For example: Permittivity, solid surface roughness, chemical composition, etc. It has been observed that streamer inception voltages at interfaces with solids of higher permittivity to that of the mineral oil are statistically similar. Additionally, streamer inception voltages of streamer initiated free in the oil (no liquid/solid interface) are similar to that of the inception voltage of cases with solids with high permittivity. In contrast, the inception voltage of streamers initiated at permittivity matched interfaces are shown to be highest of the cases. The streamer inception voltage is also studied for different distances between the liquid/solid interface and the point electrode with a permittivity matched interface. The results show a dependency of the inception voltage and the distance between the point electrode and the interface. Finally, an analysis of the observation is performed to show that the Townsend‐Meek criterion cannot predict the obtained results.

The performance of oil-impregnated paper significantly affects the safety and reliability of transformers. Previous studies on water reducing the breakdown strength of oil-impregnated paper have been mainly due to increasing charge carriers and conductivity. However, the influence of water on the cellulose crystal structure of oil-impregnated paper is still not clear; in particular, its role on breakdown strength remains ambiguous. In this study, the AC breakdown strength and crystal structure of vegetable and mineral oil-impregnated paper with different moisture contents were investigated. The results show that with increasing moisture content, the cellulose crystallinity and crystal size increases linearly, while the breakdown strength decreases. The breakdown strength of vegetable oil-impregnated paper is higher than that of mineral oil-impregnated paper and is less affected by moisture. Herein, a model is proposed on the effects of water on the crystal structure of oil-impregnated paper and the correlation of breakdown strength with crystal structure is reported. [ABSTRACT FROM AUTHOR]

Interest in using vegetable oils as dielectric coolants in power transformers dates back to the early studies on linseed- and castor- based fluids as possible replacements of mineral oil. However, interest in vegetable oils was lost due to their high viscosity and their tendency to oxidize. But, in the early 1990s and due to environmental concerns, the interest in dielectric fluids based on vegetable esters re-emerged. As a result, two vegetable ester? based oils were developed, namely, BIOTEMP, developed by ABB, and FR3?, developed by Cooper Power Systems. [ABSTRACT FROM PUBLISHER]

The combination of a dielectric solid (paper) and a dielectric liquid (mineral, vegetable, or silicone) is the most commonly used insulation system in power transformers because of the favorable dielectric properties of these insulations and the high heat capacity of the oil, which allows for cooling. It is known that temperature is the main parameter in determining the aging of these insulations and, therefore, the lifetime of a power transformer. [ABSTRACT FROM PUBLISHER]

Ex-situ mineral carbonation, a CCU process, is one possible approach for the decarbonisation of emission-intensive industry with hard-to-abate process emissions like the cement industry. The chemical reaction ensures long-term binding of carbon dioxide in minerals with the effect of storing otherwise emitted CO 2 long term. As a major hurdle for CCU processes is often their economic viability, to create incentives for the usage of this process, these carbonated mineral products must become marketable. A separation approach for the reaction products of this process and possible utilization paths are presented. The separation results in three different fractions, each enriched in either the reaction products amorphous silica or magnesium/calcium silicate or unreacted peridotite. The fractions enriched with reaction products are tested as supplementary cementitious material in cement or as a filler in rubber and paper. The application tests show promising results, comparable or even better than the conventional product. Additionally, based on the laboratory explorations, we present initial economic and environmental investigations showing potential carbon footprint reductions of up to 27% for blended cement with a total global reduction potential of 681 Mt CO2e /a. Also, potential carbon footprint reductions of 52% can be achieved by using carbonation products as fillers in rubber and 197% in paper, respectively. While the costs for the utilization of carbonated minerals have been calculated to be higher than for the conventional products, CO 2 emission certificates could ensure the same price for cement and even lower costs for the substitution of fillers in paper and rubber. [Display omitted] • The technical feasibility of the separation of the carbonation products by centrifugal classification has been proven. • Yield of the separation process can be optimized by better liberation of the particles. • Application tests for cement, paper or rubber show the potential of the carbonated and separated products as a (partial) substitute. • The modeled industrial process – in this case a cement plant with carbonation products as clinker substitute – is ecological and economical feasible. [ABSTRACT FROM AUTHOR]

The in-service evaluation of moisture in transformer insulation is a very important aspect in the condition assessment of power transformers because moisture in cellulosic materials leads to significant reductions in both dielectric and mechanical strengths by one-half for each doubling of water content [1]. Moisture equilibrium charts provide a quick way of estimating the in-service moisture content of transformer insulations. Knowledge of the moisture distribution within the various materials, which are dependent on diffusion and absorption? desorption processes, are valuable in insulation diagnostics and dry-out processes. [ABSTRACT FROM PUBLISHER]

The lifetime of a power transformer is typically defined by the lifetime of the cellulose insulation in the transformer. As the paper ages, there is a reduction in its mechanical strength properties. Dakin [1] was the first to show that the temperaturerelated chemical changes to the paper followed an Arrhenius relationship. The Arrhenius relationship shows, for example, life can be decreased to half for every 6 to 7°C rise in temperature in the hot spot temperature range of 80 to 100°C; the doubling rate can range from 5.9 to 9.7°C in the 80 to 180°C range [2]. It has also been long understood that the aging of cellulose is influenced by the amount of oxygen or water in the paper and the surrounding insulating medium [3], [4]. Paper and pressboard consist mainly of cellulose fibers composed of a polymeric chain of cellulose, which is formed from D-glucose monomers. The reduction in mechanical strength described above is due to splitting of the cellulose polymer by the action of oxygen, water, temperature, and likely acids. The number of D-glucose monomers in the cellulose fiber is termed the degree of polymerization (DP). New oil-impregnated cellulose typically has 1,000 to 1,100 individual monomers in the cellulose polymer. The DP of cellulose at its traditionally accepted end of life is 150 to 200. This article will first provide a review of data from aging studies performed on cellulose (both Kraft paper and pressboard) impregnated separately in mineral oil and BIOTEMP (ABB, USA), a high oleic sunflower based fluid. Next, possible mechanisms that explain the differences in aging behavior will be discussed. The article concludes with recommendations for new temperature limits for BIOTEMP-impregnated transformers in comparison with mineral-oil-impregnated transformers. [ABSTRACT FROM PUBLISHER]