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... in the traditional printing/writing paper, mineral-based fillers and pigments can also be used to produce cellulosic paper with functional applications (Shen, Song, Qian, & Ni, 2011;Wu, Qian, Shen, & Song, 2008). ...
... Recently, much research effort has been made to develop biodegradable carbohydrate-based organic fillers and pigments derived from renewable bioresources (Bolivar, Venditti, Pawlak, & El-Tahlawy, 2007;Karvinen, Mikkonen, & Silvennoinen, 2005;Karvinen, Oksman, Silvennoinen, & Mikkonen, 2007;Koivunen, Alatalo, Silenius, & Paulapuro, 2010;Koivunen, Paulapuro, & Silenius, 2007;Koivunen, Silenius, Laine, & Vuorinen, 2007a;Koivunen, Silenius, Laine, & Vuorinen, 2007b;Krogerus, 1999;Mikkonen et al., 2007;Mikkonen, Putkisto, Peltonen, Hyvärinen, & Koivunen, 2010;Mollaahmad, 2008;Myllymäki, Aksela, Kangaslahti, & Silenius, 2006;Patel, Venditti, Pawlak, Ayoub, & Rizvi, 2009;Patel, Venditti, & Pawlak, 2010;Peltonen, Mikkonen, Qvintus-leino, Varjos, & Kataja, 2007;Penttilä, Lumme, & Kuutti, 2006;Putkisto, Mikkonen, Hyvärinen, & Peltonen, 2009;Saari et al., 2005). The substitution of mineral or petroleum-based fillers and pigments with these renewable organic fillers/pigments has many advantages, for example, it can decrease the environmental impact associated with paper recycling, decreased abrasion to processing equipment (e.g., paper machine wire, paper cutters), and foster the sustainable development of papermaking industry (Shen, Song, & Qian, 2007;Wu et al., 2008). The use of carbohydrate-based organic fillers/pigments would have strategic significance to the global papermaking industry. ...
The replacement of traditional mineral fillers and pigments with environmentally friendly carbohydrate-based organic materials is beneficial to paper recycling, bioenergy production from paper or deinking sludge, alleviation of abrasion of paper machine wire and paper cutters, etc., yet there are still some technical barriers or challenges associated with the use of these organic materials in such aspects as manufacturing costs and structural stabilities. In this paper, the emerging technologies of carbohydrate-based fillers and pigments for papermaking are reviewed. The carbohydrate-based fillers and pigments available in the literature are based on starch, cellulose, disaccharide, xylan, or carbohydrate-rich ligno-cellulosic forest residues, while the starch-based fillers and pigments have been the most frequently reported. The mineral fillers surface-modified with carbohydrate-based materials is not included in this paper as inorganic minerals are the major component of the modified fillers.
Pressure and position sensors are usual components of many electronic devices. They equip cars and planes for security and presence sensing, industrial automated systems and many other Human-Interface Devices for medicine and kinesiology robotics, video games, etc. We present alternative ways to develop our selves these sensors using a low cost material: conductive paper loaded with carbon black pigments. We show that such a paper can be easily used to develop position, pressure and flexion sensors and that it is a good basis to develop more refined sensors such as accelerometers or tilt sensors for shock sensing with smart packaging. We last compare a few trials to produce oneself this paper using conventional fibers such as TMP, chemical or recycled pulp using classic laboratory handsheet formers and mixing those with industrial carbon black loaded papers.
Composite titanium dioxide (TiO2)-zeolite sheets were prepared using a papermaking technique and were tested with regard to their ability to remove acetaldehyde, which is often used as a typical volatile organic compound. It was demonstrated that the composite TiO2-zeolite sheet could remove acetaldehyde much more effectively under UV irradiation than a sheet of TiO2 alone. Acetaldehyde removal by a composite TiO2-zeolite sheet with a TiO2/zeolite ratio of 1 : 4 was particularly effective under the conditions adopted in this work although the composite sheet contained only one fifth of the amount of TiO2 in the TiO2 sheet. Additionally, the combination of TiO2 and zeolite was a useful method to solve the disadvantage of adsorbents, which were the decrease of the performance when the material was saturated or equilibrated with the adsorbates. Consequently, a composite TiO2-zeolite sheet can be utilized as a high functional material to prevent environmental pollution.
This review article highlights progress in understanding the optical properties of paper. Paper's appearance can be defined in terms of its opacity, brightness, color, fluorescent properties, gloss, and various quantities related to its uniformity. The phenomena that give rise to paper's optical properties, especially its ability to scatter and absorb visible light, are highly dependent on paper's structure and its chemical composition. In an effort to engineer low-cost products having relative high opacity and brightness, it is necessary to optimize the material selection and processing conditions. The dimensions of solid materials and void structures within the paper are key factors for optimizing the optical properties. In addition, additives including bleaching agents, mineral particles, dyes, and fluorescent whitening agents can impact paper's optical properties Paper's appearance depends, in subtle ways, on the processes of its manufacture.
A procedure for producing magnetic paper by in situ synthesis of
substituted (Co, Ni) ferrites is described. Ferrites are formed in the
presence of cellulose fibers and then forced to enter into the fiber
lumen where they stay protected from mechanical influences. The
remaining particles are washed out of the fibers leaving its external
surface clean, so that its papermaking properties are not affected.
Multilayer papers were prepared in which the colored magnetic layer is
hidden behind white printable surfaces. Finally, the magnetic properties
of the different kinds of obtained papers are compared with typical
commercial standards, like subway tickets and airport boarding passes
Paper, invented more than 2,000 years ago and widely used today in our everyday lives, is explored in this study as a platform for energy-storage devices by integration with 1D nanomaterials. Here, we show that commercially available paper can be made highly conductive with a sheet resistance as low as 1 ohm per square (Omega/sq) by using simple solution processes to achieve conformal coating of single-walled carbon nanotube (CNT) and silver nanowire films. Compared with plastics, paper substrates can dramatically improve film adhesion, greatly simplify the coating process, and significantly lower the cost. Supercapacitors based on CNT-conductive paper show excellent performance. When only CNT mass is considered, a specific capacitance of 200 F/g, a specific energy of 30-47 Watt-hour/kilogram (Wh/kg), a specific power of 200,000 W/kg, and a stable cycling life over 40,000 cycles are achieved. These values are much better than those of devices on other flat substrates, such as plastics. Even in a case in which the weight of all of the dead components is considered, a specific energy of 7.5 Wh/kg is achieved. In addition, this conductive paper can be used as an excellent lightweight current collector in lithium-ion batteries to replace the existing metallic counterparts. This work suggests that our conductive paper can be a highly scalable and low-cost solution for high-performance energy storage devices.
Magnetic papers have been successfully prepared from unbleached kenaf (hibiscus cannabinus) kraft pulps via the lumen loading and in situ synthesis process. The lumen loading method allows the magnetic fillers to be introduced into the lumen of fibres and at the same time leaving the external surfaces free from filler, resulting the better inter-fibre bonding and subsequently its papermaking properties are not affected. Fillers, which deposited in the lumen of fibres will be protected from further mechanical influences. For the lumen loading process, commercial magnetite (Fe3O4) powders have been introduced into the lumen by mixing the pulp and magnetic powder. For the in situ synthesis process, nanosized magnetite particles have been precipitated in the presence of pulp fibres and deposited inside the lumen of fibres via chemical coprecipitation process. The samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and their magnetization properties were examined by a vibrating sample magnetometer (VSM). The loading degree of the papers was estimated by using the Thermogravimetric analyzer (TGA). The VSM results show that the magnetic properties of the lumen loaded papers are higher compared to the in situ synthesis papers in which can be explained that the nanosized magnetite particles possess superparamagnetic properties. However, the SEM micrograph shows that the size and the distribution of the magnetic particles inside the lumen for the in situ synthesis papers are much better than that of the lumen loading papers.
The article contains sections titled: 1.
Fibrous Materials
1.1.
Chemical Pulp
1.2.
Mechanical Pulp
1.3.
Recovered Paper, Recycled Fibers
1.3.1.
Role of Recovered Paper in the Paper and Board Industry
1.3.2.
Main Definitions for Statistics
1.3.3.
Utilization Rates for Different Paper Grades
1.3.4.
Resources of Recovered Paper
1.3.5.
Lists for Recovered Paper Grades
1.3.6.
Use of Recovered Paper Grades
2.
Mineral Additives
2.1.
Pigments as Fillers
2.1.1.
Why Use Fillers?
2.1.2.
Choice of Fillers
2.1.3.
Characterization of Fillers
2.1.4.
Main Mineral Fillers
2.1.5.
Specialty Filler Pigments
2.2.
Coating Pigments
2.2.1.
Main Coating Pigments
2.2.2.
Special Pigments
2.2.3.
Additional Pigments
The incorporation of fillers in paper has been common practice for many years. Though the term ‘filler’ is somewhat uncomplimentary, this group of predominately inorganic materials has become a very essential component of many grades of paper. The original purpose of adding filler to the paper matrix was to lower furnish costs with the amount of filler limited only by strength considerations. Today the principal need for fillers is to impart specific quality improvements to the sheet. Depending on the performance characteristics of the fillers and the amount added to the paper, these products can improve the optical, physical, and aesthetic properties of the finished sheet. Today the practice of utilizing fillers is based on choosing materials which will provide both cost and quality improvements. The conversion to alkaline papermaking in North America has emphasized this approach, where fillers designed to add value to the paper are routinely used. This trend has been confirmed by the rapid growth in the tonnage of valued-added speciality fillers purchased by paper mills.
Nano-structured calcium silicate is a proprietary new material comprising nanosize platelets that self-assemble into particles of about 1-5 mu m in size with an open framework structure. These exhibit a high pore volume and liquid absorption capacity of about 500-600 g oil 100 g(-1) silicate and a high accessible surface area of up to about 500 m(2) g(-1), both of which are controllable in the synthesis process. It has a high whiteness and brightness. Alkane phase change materials (PCMs) can readily be accommodated in amounts up to 300-400 wt% in the pores of the silicate to yield a new composite phase change material with a thermal buffering capacity of about 100-110 J g(-1). Above the PCM melting point, the liquid phase is fully contained in the pores with the composite material remaining as a powdery solid. The new nano-structured calcium silicate - PCM composite can be incorporated into liners and coating formulations to impart effective thermal buffering to packages and paper board coatings. The preparation and characterisation of the thermal properties of this nano-structured calcium silicate - PCM composite are presented here.
Flame retardancy was imparted through the addition of an organophosphorus agent which enhances paper utilisation and increases the value of paper products. For that purpose paper was impregnated with a solution containing a flame retardant agent, a binder and its catalyst, which was then linked during the curing step. N-hydroxymethyl-3-dimethylphosphonpropionamide was used as the organophosphorus flame retardant (FR) agent with two types of binders: either melamine formaldehyde or citric acid. The use of a bonding agent is necessary in order to form covalent linkages between the FR agent and cellulose macromolecules. The first binder type implements an etherification mechanism which requires phosphoric acid for the catalysation. Second binder type implements esterification mechanism which requires phosphono based catalysts. Citric acid represents a new class of environmentally friendly agents, and as such is recommended for usage. A non-durable flame retardant based on boron compounds was used in the study for comparison. Flame retardancy was tested according to the ISO 6940 and 6941 methods, as well as with the limiting oxygen index (LOI) technique according to ASTM D 2863-97, while the tensile indices were measured according to ISO 1924-2.
The possibility of application of Mg-Al hydrotalcite (HT) as a flame-retardant filler in papermaking and its influence on the properties of the paper were investigated. The experimental results showed that Mg-Al hydrotalcite can increase the opacity and brightness of the paper, at the same time, it can decease the strength properties of the paper in a certain degree. Without adding CPAM and with filling 40% Mg-Al hydrotalcite, the oxygen index of the paper is above 25% and the paper belongs the grade which is difficult to burn. The oxygen index reaches 26.2% when adding 0.025% CPAM and filling 30% Mg-Al hydrotalcite. The oxygen index is close to 25% when the basis weight of the paper is 240g/m2 and Mg-Al hydrotalcite dosage is 20%, and the paper basically reaches the grade which is difficult to burn.
The feasibility and technological conditions of the preparation of flame retardant paper based on fiber loading technology using in-situ synthesis of Mg-Al hydrotalcites in the lumen or cell wall of the pulp fibers were investigated. Sodium hydroxide solution, sodium carbonate solution and sodium meta-aluminate solution were added into the dispersed fibers, then magnesium chloride solution was added. The effects of reactant concentration, reaction temperature and reaction time on the various performances of flame retardant paper were systematically studied. The results indicated that preparing flame retardant paper based on fiber loading technology using in-situ synthesis of Mg-Al hydrotalcites in the pulp fibers is feasible. The oxygen index of the flame retardant paper produced is above 25% and reaches the grade which is difficult to burn when the deposition of Mg-Al hydrotalcites in the pulp fibers is higher than 25%. The deposition of Mg-Al hydrotalcites on the fiber surface, in the cell wall and lumen of the pulp fibers is found by SEM observation.
The influences of carbon fibers length, wet pressing, wood fiber beating and its proportion on the conductive property of the carbon fiber conductive paper were investigated in this paper. The influencing mechanism was introduced and discussed. It was found that the carbon fibers length has very important effect on the conductive network; wet pressing, wood fiber beating and wood fiber proportion affect the contact resistance greatly. By adjusting the carbon fibers length, wood fiber proportion and papermaking process, conductive network can be optimized and the conductivity of the paper can be enhanced.
The feasibility of producing paper with antibacterial properties based on the photocatalytic activity of TiO2 (anatase) was evaluated. Eighty percent of the bacteria deposited onto photocatalytic paper, were killed by thirty minutes exposure to 25 W/m2 UVA. To achieve this effect it was determined that the water content of the paper must be 40% or greater, and the TiO2 must be located on the exposed surface because UV intensity is attenuated by paper. Finally, the target bacteria must also be on the paper surface to be treated; the reactive oxygen species generated by photocatalysis are too reactive to persist in solution. The decolourisation of anionic reactive black 5 is an effective assay for photocatalytic activity, except when the paper is impregnated with cationic wet strength resin, which strongly adsorbs the dye.
Catalytic Paper has virtues of suspended TiO 2 and immobilized TiO 2 which opens up a new research field for its application in environmental pollution controlling. In order to increase the strength of catalytic paper inorganic fibers are used as the carrier of TiO 2. The catalytic activity can be improved by adding zeolite, depositing noble metal on TiO 2 and using other semiconductor as catalytic. The main application of catalytic paper are minerization of noxious organic matters, sterilization and used as catalyst in chemical reactions. Finally, it is pointed out that four problems must be solved in order to prepare catalytic paper with high strength and high catalytic activity.
Distribution of magnetite components present in magnetic pulps, which were prepared by in situ synthesis according to the previously reported method, was studied. Transmission electron microscopic (TEM) observations and electron diffraction analysis combined with TEM revealed that highly crystalline magnetite particles were present in the magnetic pulps. Mapping analysis of the magnetic pulp using iron of magnetite as a marker element was then carried out by means of an energy-dispersive X-ray analyzer attached with TEM. The obtained results showed that magnetite was formed in micropores in cell walls of the magnetic pulps. Also in the case of magnetic pulps prepared by in situ synthesis of manganese-ferrite, zinc-ferrite and manganese-zinc-ferrite, it was indicated that these ferrite components were present in micropores in cell walls.
The mechanical strength of magnetic lumen loaded handsheets was reported to be lower than the unloaded handsheets. This effect is due to the deposition of filler inside the fiber lumen and some on the fibre surface which interfere with the fibre to fibre bonding. Hence, in order to improve the handsheets strength, cationic starch is used as a dry strength additive. In this study, mixed tropical hardwood pulps were used throughout the experiment. The magnetite particles were deposited in the fibre lumen via the lumen loading technique. The addition of cationic starch was found to increase the handsheet strength. However, it disturbed and influenced the location and distribution of the magnetic fillers. Some of the magnetite particles were observed to be displaced from the fiber lumen and pit apertures. The charges of the filler particles and cationic starch played an important role in producing charge repulsion and pulling effect which lead to filler dislocation.
Magnetic paper was prepared from unbleached kraft pulp lumen-loaded to 10-21% with ferrites. While addition of aluminum sulphate to the lumen-loading process had little effect on maghemite adsorption, the inter-stage treatment of lumen-loaded pulp with 0.5% cationic polyethylenimine at pH 5.5 for 23 h increased pigment retention in the fibre lumens by 110%. Multilayered paper containing fibres loaded with maghemite exhibited bulk magnetic properties comparable to commercial storage and identification media. The utilization of bleached kraft pulp as the outer layer of a multi-ply sheet increased brightness by 25 units.
NB This study explored and demonstrated one possibility of the "fiber engineering" concept via an in-situ chemical polymerization methodology, specifically, to deposit polypyrrole on fiber surface and thus render cellulose fibers electrically conductive: not only a novel functionality was imparted to pulp fibers but processability of the intrinsic conducting polymer (ICP) was greatly improved. Reaction and processing conditions were optimized in terms of electrical and mechanical properties of the paper sheet prepared from the modified fibers, and the resultant hybrid material was characterized with respect to its chemistry and polypyrrole distribution. Good adhesion of the conductive polymer to fibers was achieved. It was found that with the same amount of monomer used, paper obtained by mixing treated fibers with untreated ones had higher conductivity while having higher tensile strength compared with paper obtained exclusively from treated fibers. The percolation model and a multiple-percolation-theory were adopted for the first time to describe such paper-conducting polymer composites and to explain this interesting experimental finding.
The main purposes of filler addition in papermaking are to improve paper properties and reduce cost. The cost reduction is attributed to the low cost of the filler itself and to the energy savings that occur during the papermaking process. In this work, the effects of clay filler addition on the energy savings during the papermaking process, including water drainage, pressing, and drying, were systematically investigated. Experimental results indicated that the addition of filler could dramatically increase the drainage rate and the water removal rates during pressing and drying. With 20% filler addition, the drainage time decreased by 20% compared to the unfilled paper. At a filler content of 23%, the solids content of the handsheets after pressing increased at least 5 absolute points, and the drying rates increased by 20%. All these improvements can offer considerable benefits for paper mills, including enhanced machine speeds and large energy savings.
During the past decade semiconductor nanocrystals have been studied extensively, in particular ZnS nanocrystals doped with optically active luminescent centres. Such materials have created new opportunities in the areas of photo-voltaic solar cells and light-emitting diodes. In this study, photoluminescent cellulose fibres were prepared by coating bleached Kraft fibres (Pinus radiata) with ZnS nanocrystals doped with Mn2+ and Cu2+ ions. In doing so, the inherent properties of the fibre (such as tensile strength and flexibility) have been preserved, but imparted to it are the photoluminescent properties of the coating. A wet chemical synthesis method was used in which homogenous solutions of zinc salts and transition metal salts were precipitated with sodium sulfide. Dopant concentrations ranged from 0.1 to 2 wt%. After successive washings and sonication, the particles remained bonded to the surface of the fibre, and the fibres were able to be formed into a paper sheet. Samples were characterized by photoluminescence spectroscopy, scanning electron microscopy, X-ray diffraction, energy dispersive spectroscopy and X-ray photoelectron spectroscopy.
TiO2-containing papers with highly photocatalytic activity have been prepared. Their photocatalytic activity was investigated by measuring the decomposition of gaseous acetaldehyde under illumination from a weak UV light source such as a conventional white fluorescent light bulb. It was found that the photocatalytic efficiency of the TiO2-containing papers was higher than that of Degussa P-25, one of the most efficient commercial TiO2 powders, indicating that paper pulp serves as a good matrix for highly efficient TiO2 photocatalysts.
In situ synthesis of iron oxide particles in O-(carboxymethyl)ated cellulose fibers and sulfonated wood fibers was performed by careful oxidation of ferrous hydroxide precipitated by alkali from the ferrous ion-exchange form of the matrix. This “biomimetic” chemistry yielded magnetic fibers containing small ferrite (Fe3O4) particles of ∼ 10 nm in size. Magnetic hysteresis-loop measurements showed that the material, in the form of a thin parchment-like film, is superparamagnetic, that is, it possesses no remanent magnetization. The process described herein could be practiced with a wide range of natural biopolymers in order to obtain magnetically responsive materials suitable for such biotechnological applications as magnetic separations.
One of the processes for the preparation of magnetic paper is the in-situ synthesis of magnetic particles, i.e. magnetite and substituted ferrites. This process gives rise to the formation of ferrite particles associated with or inside the cellulose fibers. In this work, the influence of the fibers during the synthesis of crystals and aggregates of ferrites is evaluated. The magnetic, morphological and structural properties of the magnetic paper and the ferrite particles obtained are reported.
Magnetic cellulose fibres have been successfully produced by the lumen-loading process. Lumen loading allows filler particles to be introduced exclusively into the lumens of wood fibres while leaving the external surfaces free of filler. The filler is protected by the cell wall from dislodgement during papermaking and the particles do not interfere with inter-fiber bonding. This leads to a lumen-loaded fibre with high resistance to unloading during papermaking and result in papers with a higher strength than those conventionally loaded. Kenaf and black spruce pulp have been loaded with magnetite (Fe3O4). To improve the lumen loading degree, polymeric retention aids have been introduced. Polyethylenimine (PEI) as retention aid in the preparation of lumen-loaded fibre has been found beneficial in the preparation of magnetic cellulose fibres. The maximum lumen loading degree 0.235g/g pulp was achieved. The factors, which affect the lumen loading degree, included dosage of PEI, pulp drying history, impregnation time and speed. The characteristics of the magnetite surface and its behaviour in water solution in the presence of PEI and aluminum sulfate, the mechanism of adsorption and the kinetics of lumen loading are fully elucidated. Electrophoretic mobility of magnetite is positive in acidic solution and becomes more negative with increasing pH. pHpzc is about 5.5. The magnetite particles are negatively charged without any addition of PEI. The particles reach the point of zero charge when ∼0.15mg/g pigment of PEI is added and become positively charged with further addition of PEI.
Conducting polymers have generated a great deal of interest because of their physical and chemical properties as well as their potential in industrially useful materials. However, one of the shortcomings of most conducting polymers is that they are often formed as intractable films that are difficult to process [1]. To overcome this problem we have incorporated various conducting polymers into sheets of paper in order to create new composite materials which combine the universal properties of a paper sheet or paper products with the chemical and electrically conducting properties of the conducting polymer.Various composite paper – conducting polymer products have been prepared by polymerizing polypyrrole and polyaniline directly onto the paper sheet using ferric chloride as the oxidant. Electronmicroscopy shows that the polymers comprise spheres of about 50–150 nanometers in size fused together such that they fully encapsulate the individual cellulose fibres in the paper sheet. The open matrix of fibres characteristic of the original paper sheet is maintained and hence provides a much greater specific surface area for the conducting polymer than that of a continuous flat sheet which would be the case if the polymer simply formed a laminar coating on the paper surface. In the case of polyaniline, it was also possible to form a different morphology of the polymer comprising a mix of nano-size spheres, rods and plates using ammonium persulfate as the oxidant. Conductivities of up to 6 Scm−1 have been measured for paper-polypyrrole composites and up to 2x10−3 Scm−1 for paper-polyaniline composites.
A new nano-structured calcium silicate (NCS) – phase change composite material has been developed to provide effective thermal buffering for paperboard packages during the transport and temporary storage of chilled perishable food from the supplier to the market. NCS is a proprietary material comprising nano-size platelets stacked together in a unique open framework structure having a high pore volume and liquid absorbency. Alkane phase change materials (PCMs) which absorb and release latent heat energy (∼160–190Jg−1) can be used in heat storage and release applications as they are non-toxic and their operating temperature range can be tuned by the hydrocarbon chain length. The major practical problem of containing the liquid phase has been overcome here by incorporating the alkane PCM (Rubitherm RT6, melting point 8°C) into the highly porous NCS matrix to a level of about 300 wt% of NCS. A paperboard container constructed and lined with six bubble wrap “Post-It” bags containing 400g NCS-300PCM composite provided sufficient thermal buffering capacity to maintain the temperature inside the container at 10°C for some 5h after the outside temperature had increased to about 23°C. A similar performance was obtained when the container was filled with 2kg of asparagus, as a model for perishable food. The NCS-300PCM composite therefore provides sufficient thermal buffering to ensure perishable food in a paperboard container remains below 10°C during transport and temporary storage en route from the supplier to the market.
Superparamagnetic cellulosic fibers were prepared by synthesizing ferrites by an in situ method. Five cycles of the reaction were performed on the following four substrates: sodium carboxymethylcellulose lap pulp (Na-CMC), calcium alginate fibers, continuous filament rayon tire cord, and sulfonated thermomechanical wood pulp (TMP). Vibrating sample magnetometry showed that the sulfonated TMP exhibited the highest saturation magnetization (∼25 J/T/kg of sample after five cycles of reaction). TEM micrographs of sections of sulfonated TMP fibers showed that the largest concentration of ferrites (∼100 Å in size) were arranged at the external fiber surfaces. The micrographs also showed ferrites of less than 20 Å in size, dispersed across the fiber cell wall. Electron diffraction indicated that the major components of the oxides were γ-Fe 2O 3 (needles) and Fe 3O 4 (disks). Room-temperature Mössbauer spectra of the sulfonated TMP, after the in situ reaction, indicated the presence of small superparamagnetic ferrites for the first and second cycle samples. A ferrimagnetic component was observed for the third cycle sample and predominated in the fourth and fifth cycle samples as a result of larger ferrite grains being formed both on the surface and inside the lumen of the pulp fibers.
Conductive papers were developed for preventing or reducing electromagnetic interference (EMI), and their shielding efficiency was evaluated. This type of conductive paper consists of wood pulp, synthetic pulp and metallized polyester fibers (0.5–2.0 mm long and 14 m in diameter) whose surfaces are coated with nickel alone (Ni-PET) or copper and nickel double layers (Ni-Cu-PET) by electroless plating. In this report, the effect of the characteristics of these metallized fibers, such as their conductivity, geometry and the concentration of fibers in paper, which lead to high efficiency for shielding effectiveness is discussed. For instance, one of the conductive papers (80 g/m2) which was prepared by mixing 40% Ni-Cu-PET and 60% synthetic polyethylene pulp showed over 40 dB shielding effectiveness between 10 MHz and 1 GHz.
Magnetic pulps were prepared from unbleached kenaf (hibiscus cannabinus L.) kraft pulps. Fe3O4 or magnetite powder was used to load into the pulp’s lumen and pit. Aluminum sulphate [Al2(SO4)3] (alum) and polyethylenimine (PEI), both mainly function as retention aid were used throughout the experiment and found to be beneficial in the preparation of this magnetic pulps. The ash content method was used to determine the amount of magnetite retained in the lumen and pit. The utilization of PEI up to 2% per pulp fibres was found to be the best result on lumen loading. The deposition of magnetite powder in lumen and pit is found decrease as the addition of PEI used is more than 2% per pulp fibres. Scanning electron microscope (SEM) clearly shows the distribution of magnetite deposited in the lumen. Tensile index and folding endurance of the loaded fibre decreased slightly as the percentage of loading pigment increased.
Two types of powders, titanium dioxide (TiO2) photocatalyst and zeolite adsorbent, were made into a paper-like composite by a papermaking technique using a dual polyelectrolyte system. The photodegradation behavior of bisphenol A (2,2-bis(4-hydroxyphenyl)propane, BPA) in water was investigated under UV irradiation. It was found that TiO2 sheets could photocatalytically decompose BPA in an aqueous medium. Composite TiO2–zeolite sheets, however, demonstrated a higher efficiency for BPA removal from water than did zeolite-free TiO2 sheets owing to the synergistic effect obtained through the combined use of TiO2 and zeolite, as reported in our previous study. Furthermore, the total organic carbon (TOC) content of the system was reduced, evidently through the use of composite sheets, rather than a TiO2 powder suspension or zeolite-free TiO2 sheets. Trace amounts of intermediates resulting from BPA degradation were detected in the water treated with the composite sheets. In general, various intermediates are formed during the TiO2 photodecomposition of organic compounds, which can potentially cause a secondary pollution because the degradation products sometimes turn out to be more hazardous than the parent compound. The composite TiO2–zeolite sheets prepared in the present study helped to overcome this problem by allowing the elimination of BPA without the release of hazardous intermediates into water: most of the intermediates were temporarily captured by the zeolite adsorbent contained in the composite sheets, and eventually decomposed through TiO2 photocatalysis. Paper-like TiO2–zeolite composites clearly offer great advantages in efficacy and safety for the aqueous decomposition of BPA.
Unbleached kenaf fibers were selected for the manufacture of magnetic paper using chemical coprecipitation method. This method involved precipitation and loading of nano-sized ferrite particles into the lumen of the kenaf fibers. While the degree of loading depended on both the degree of agitation and temperature of the coprecipitation, the thermal stability of the produced magnetic paper depended mainly on the temperature. The magnetic particles deposited on the fiber surface had detrimental effects on the strength of the produced paper. The coercivity value of the magnetic paper depended on the type of ferrite produced from the coprecipitation.
Magnetic cellulose fibres can be prepared either by ‘lumen loading’ or by in situ synthesis of ferrites. By using the lumen-loading technology, commercially available magnetic pigments can be introduced into the lumens of softwood fibres from which magnetic paper may be prepared. Lumen-loaded fibres act as magnetic dipoles allowing manipulation of fibre orientation in papermaking. In situ synthesis of iron oxide particles is performed through oxidation of ferrous hydroxide precipitated with caustic from the ferrous ion-exchanged form of sodium carboxymethyl cellulose fibres. The latter are characterized by conductometric titration to determine the number of functional groups available for the in situ chemistry. Superparamagnetically responsive fibres have smaller and less-coloured pigments which are only magnetic in the presence of a field.
Magnetic paper lumen via loading process was prepared from never-dried and dried kraft kenaf pulp. PEI was used as retention aid during the inter-stage treatment. The paper produced from the magnetic pulp showed an increase of magnetic properties as the loading increased. The physical properties of the paper such as tensile index, burst index, tear and folding endurance showed a reduction in the strength value as the loading capacity increased. The flocculation study shows that the magnetic colloid exists in multi particles aggregates form in water solution, which caused by magneto-dipole interaction.
A well-adherent surface of titanium oxide nanoparticles was produced on cellulose fibers at low temperature from an aqueous titania sol that was obtained via hydrolysis and condensation reactions of titanium isopropoxide in water. SEM investigations of the formed titania films revealed a semi-spherical particle morphology with grain size about 10 nm in diameter. The coated substrates showed substantial bactericidal properties under UV radiation, ambient fluorescent white light and dark conditions. The possible mechanisms for the antibacterial activity are discussed. The stability of the titania coatings was investigated by comparing the UV transmission profiles of coated fibers before and after repeated washing.
A new salt-free approach was developed for fabricating conductive paper by layer-by-layer (LBL) assembly of conductive indium tin oxide (ITO) nanoparticles and polyelectrolytes onto wood fibers. Subsequent to the coating procedure, the fibers were manufactured into conductive paper using traditional paper making methods. The wood fibers were first coated with polyethyleneimine (PEI) and then LBL assembled with poly(sodium 4-styrenesulfonate) (PSS) and ITO for several bilayers. The surface charge intensity of both the ITO nanoparticles and the coated wood fibers were evaluated by measuring the zeta-potential of the nanoparticles and short fibers, respectively. The ITO nanoparticles were found to preferentially aggregate on defects on the fiber surfaces and formed interconnected paths, which led to the formation of conductive percolation paths throughout the whole paper. With ten bilayer coatings, the as-made paper was made DC conductive, and its sigma(dc) was measured to be 5.2 x 10(-6) S cm(-1) in the in-plane (IP) direction, while the conductivity was 1.9 x 10(-8) S cm(-1) in the through-the-thickness (TT) direction. The percolation phenomena in these LBL-assembled ITO-coated paper fibers was evaluated using scanning electron microscopy (SEM), current atomic force microscopy (I-AFM), and impedance measurements. The AC electrical properties are reported for frequencies ranging from 0.01 Hz to 1 MHz. A clear transition from insulating to conducting behavior is observed in the AC conductivity.
In this study, magnetic cellulose fibers have been prepared by coating bleached Kraft fibers (Pinus radiata) with magnetite nanoparticles. In doing so, the inherent properties of the fiber (such as tensile strength and flexibility) have been preserved, but imparted to it are the magnetic properties of the coating. The surface coating approach used differs from other methods in the literature in which the lumen loading or in situ approach is taken. After successive washings and sonication, the particles remained bonded to the surface of the fiber, and the fibers could be formed into a paper sheet. The chemical and physical characterization of these materials were carried out using scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and SQUID magnetometry. SEM shows the surface of the fibers to be completely encapsulated by the ferrite nanoparticles. This is also confirmed by EDS. XRD line broadening analysis shows the average particle sizes of the nanoparticles range from 12-26 nm. Magnetically responsive cellulose fibers such as those synthesized in this study, will allow the investigation of new concepts in papermaking and packaging, security paper, and information storage. Potential applications are in electromagnetic shielding, magnetographic printing and magnetic filtering.
A novel paper-based material containing titanium dioxide (TiO(2)) photocatalyst was successfully prepared by a papermaking technique with the internal addition of inorganic fibers on which TiO(2) particles were supported. Photodegradation performance of acetaldehyde gas, an indoor pollutant, and the durability of the TiO(2)-containing papers were investigated under UV irradiation. Ceramic fiber suspension and polydiallyldimethylammonium chloride as a cationic flocculant were mixed, followed by the addition of TiO(2) suspension and anionic polyacrylamide. Subsequently, the inorganic mixture was poured into a pulp suspension, and TiO(2) handsheets then prepared by a papermaking method. The tensile strength of TiO(2)-containing paper without a ceramic carrier decreased by more than 30% after 240-h UV irradiation (2 mW/cm(2)), although the strength of the TiO(2) sheet with ceramic fibers remained reasonably stable. The efficiency of acetaldehyde decomposition by the TiO(2) paper containing an inorganic carrier was nearly equal to that of the carrier-free TiO(2) paper. Scanning electron microscopic observation suggested that most TiO(2) particles were predominantly supported on the inorganic fiber matrix, and were mostly out of contact with organic pulp fibers. The TiO(2) paper with an inorganic carrier demonstrated both excellent photocatalytic performance and durability, which before had been mutually incompatible for organic materials containing TiO(2) photocatalyst. The two-stage mixing procedure for TiO(2) sheet-making is promising for the simple manufacture of high performance paper with photocatalytic ability.
Toluene and formaldehyde are malodorous and cause indoor pollution. These materials have received much attention as hazardous and malodorous substances. It is well known that long-term exposure to even fairly low levels of toluene and formaldehyde brings about the risk of asthma and eczema. In this study, a composite TiO2-zeolite (ZE) sheet prepared using a papermaking technique was applied to remove toluene and formaldehyde under UV irradiation. The optimum composition of the TiO2 (Ti)-ZE sheet was studied in detail with regard to the effective removal of various indoor pollutants. Gaseous toluene and formaldehyde were removed by a composite TiO2-ZE sheet with different efficiencies depending upon the ratio of Ti/ZE in the composite sheet. The composite sheets could decompose formaldehyde and toluene repeatedly after being recharged. It was shown that the sheets are potentially applicable as highly functional materials to be placed on walls and ceilings of houses for the removal of various indoor pollutants.
Photocatalytic paper encompasses a range of materials based on paper and nonwoven fabrics which performs a function based on the light-activated catalytic activity of colloidal TiO(2). The literature describing photocatalytic paper is surveyed, including mechanisms, applications, limitations and future opportunities. The technology is in its infancy with less than 10 patents and as many scientific publications appearing over the last decade. The main applications described are the destruction of organic molecules (mineralization) and photo-disinfection (sterilization). These disclosures build upon a much larger literature describing photochemical properties of TiO(2) both supported on non-cellulose substrates or simply as suspended particles in water or air. Current photocatalytic paper developments include methods to fix TiO(2) to cellulose substrates to minimize photochemical damage to the paper. Another theme is the use of multiple approaches, such as zeolites, for enhanced mineralization, and metals, such as silver and copper, for enhanced photocatalytic disinfection.
TiO2 powder-containing paper composites, called TiO2 paper, were prepared by a papermaking technique, and their photocatalytic efficiency was investigated. The TiO2 paper has a porous structure originating from the layered pulp fiber network, with TiO2 powders scattered on the fiber matrix. Under UV irradiation, the TiO2 paper decomposed gaseous acetaldehyde more effectively than powdery TiO2 and a pulp/TiO2 mixture not in paper form. Scanning electron microscopy and mercury intrusion analysis revealed that the TiO2 paper had characteristic unique voids ca. 10 microm in diameter, which might have contributed to the improved photocatalytic performance. TiO2 paper composites having different void structures were prepared by using beaten pulp fibers with different degrees of freeness and/or ceramic fibers. The photodecomposition efficiency was affected by the void structure of the photocatalyst paper, and the initial degradation rate of acetaldehyde increased with an increase in the total pore volume of TiO2 paper. The paper voids presumably provided suitable conditions for TiO2 catalysis, resulting in higher photocatalytic performance by TiO2 paper than by TiO2 powder and a pulp/TiO2 mixture not in paper form.
The opacifying power of synthesized polycrystalline TiO2 particles in a cellulose matrix was found experimentally and theoretically to be superior to that of a commercial rutile pigment, depending on crystal structure of the synthesized particles. The crystal structure of the particles was varied by calcination of amorphous titania nanoparticles at different temperatures and was characterized using SEM, TEM, and XRD. Polycrystalline anatase pigments had less opacifying power than commercial rutile, while polycrystalline pigments containing a one-to-one mixture of anatase and rutile had similar opacifying power as the commercial pigment if they have a similar overall particle size. The polycrystalline rutile pigments composed of a linear linkage of several individual rutile crystals gave 6% more opacity than the commercial rutile pigment. Theoretical light scattering calculations using the T-matrix method showed the light scattering efficiency of linearly arranged polycrystalline rutile particles to depend on number and size of crystals composing the particle. It is suggested that the efficiency of rutile pigments can be increased dramatically by controlling both the primary crystal size and the overall particle size. It is believed that the greater than expected light scattering efficiency of the biphasic pigment results from reflection and refraction of light at the grain boundaries between crystals of different phase, which have different refractive indices.
Conductivity decay of cellulose-polypyrrole conductive paper composite prepared by insitu polymerization method
- J Wang
- F Yang
- K F Chen
- R D Yang
- J Li
- M Patel
- Z Ziaee
- L Qian
- Y Guan
- P Fatehi
- H Xiao
- Y Ma
- P Liu
- C Si
- Z Liu
- X Y Chen
- X R Qian
- C Dong
- J Cairney
- Q Sun
- O L Maddan
- G He
- Y Deng
- C Ding
- X Qian
- J Shen
- X An
- B Huang
- G J Kang
- Y Ni
- L Hu
- J W Choi
- Y Yang
- S Jeong
- F L Mantia
- L F Cui
- Y Cui
Retrieved Jan. 16, 2010. URL: http://www.esf.edu/joachim/2005forum/
YDeng.ppt.
(55) Wang, J. Study on antiseptic paper and wet tissue using chitosan
and its derivatives as antimicrobial agents. Master Thesis. Tianjin University
of Science and Technology of China, 2005.
(56) Yang, F.; Chen, K. F.; Yang, R. D.; Li, J. Inorganic silverimpregnated zeolite antibiotic papers and method of producing the same.
Chinese Patent 101182689, 2008.
(57) Patel, M. Developments in antibacterial paper. 2009. Retrieved Jun.
6, 2010. URL: http://www.pira-international.com/Core/DownloadDoc.aspx?documentID)1385.
(58) Ziaee, Z.; Qian, L.; Guan, Y.; Fatehi, P.; Xiao, H. Antimicrobial/
Antimold polymer-grafted starches for recycled cellulose fibers. J. Biomater.
Sci., Polym. Ed. 2010, 21, 1359-1370.
(59) Ma, Y.; Liu, P.; Si, C.; Liu, Z. Chitosan nanoparticles: Preparation
and application in antibacterial paper. J. Macromol. Sci., B 2010, 49, 9941001.
(60) Chen, X. Y.; Qian, X. R. Preparation of antibacterial paper by filling
tetrapod-like zinc oxide whiskers at wet end. China Pulp Pap. 2010, 29
(5), 30-34.
(61) Dong, C.; Cairney, J.; Sun, Q.; Maddan, O. L.; He, G.; Deng, Y.
Investigation of Mg(OH) 2 nanoparticles as an antibacterial agent. J.
Nanopart. Res. 2010, 12, 2101-2109.
(62) Ding, C.; Qian, X.; Shen, J.; An, X. Preparation and characterization
of conductive paper via in-situ polymerization of pyrrole. BioRes. 2010, 5,
303-315.
(63) Huang, B.; Kang, G. J.; Ni, Y. Preparation of conductive paper by
in-situ polymerization of pyrrole in a pulp fibre system. Pulp Pap. Can.
2006, 107 (2), 38-42.
(64) Johnston, J. H.; Moraes, J.; Borrmann, T. Conducting polymers
on paper fibers. Synth. Met. 2005, 153, 65-68.
(65) Johnston, J. H.; Kelly, F. M.; Burridge, K. A.; Borrmann, T. Hybrid
materials of conducting polymers with natural fibres and silicates. Int. J.
Nanotechnol. 2009, 6, 312-328.
(66) Li, J.; Qian, X.-r.; Chen, J.-h.; Ding, C.-y.; An, X.-h. Conductivity
decay of cellulose-polypyrrole conductive paper composite prepared by insitu polymerization method. Carbohydr. Polym. 2010, 82, 504-509.
(67) Hu, L.; Choi, J. W.; Yang, Y.; Jeong, S.; Mantia, F. L.; Cui, L. F.;
Cui, Y. Highly conductive paper for energy-storage devices. Proc. Natl.
Acad. Sci. U.S.A. 2009, 106, 21490-21494.
(68) Shinagawa, S.; Kumagai, Y.; Urabe, K. Conductive papers containing metallized polyester fibers for electromagnetic interference shielding.
Filler modification engineering for improved paper properties and papermaking process. TAPPI 2nd Annual PaperCon'09 Conference -Solutions for a Changing World
- D Song
- C Dong
- A J Ragauskas
- Y Deng
Song, D.; Dong, C.; Ragauskas, A. J.; Deng, Y. Filler modification
engineering for improved paper properties and papermaking process. TAPPI
2nd Annual PaperCon'09 Conference -Solutions for a Changing World,
2009.
PTS-Seminar Wet End Operations-Vorgänge in der Siebpartie
- M Laufmann
Laufmann, M. Fillers for paper: A global view. PTS-Seminar Wet
End Operations-Vorgänge in der Siebpartie, 1998. Retrieved Jun. 6, 2010.
URL:
http://www.omya.de/web/omya_at.nsf/Attachments/
DC167D8418BDC7D4C1256B6D0045017B/$FILE/Omyape1.pdf.
- K M Beazley
Beazley, K. M. Fillers -A Brief chronological review. Pap. Technol.
1985, 26 (6), 266-268.
Filler particle shape vs. paper properties -A review
- M A Hubbe
- R A Gill
Hubbe, M. A.; Gill, R. A. Filler particle shape vs. paper properties
-A review. Proceedings from TAPPI Paper Summit -Spring Technical
and International EnVironmental Conference 2004, 141-150.