Search

The use of paper dry strength additives is one of the methods for producing packaging boards with a lower grammage while maintaining mechanical properties. In the present work, papers were formed using dissolving grade kraft fibres, kraft fibres and carboxymethylated cellulose (CMC) modified kraft fibres (C-kraft fibres), with either cationic starch (CS), anionic polyacrylamide (APAM) or anionic polyelectrolyte complexes (PECs). Fibres and sheets were characterized to evaluate how the saturation adsorption of the different strength additives influences the properties of the treated fibres and the final handsheets. The tensile index of papers made from C-kraft fibres was the highest due to the highest adsorption capacity of strength additives. Moreover, the strength additives increased the tensile index by 33–84 %, while z-directional tensile strength was increased dramatically by 46–139 %. Bending stiffness was improved by 2.6–25 %, and the combination of CS and APAM or PECs resulted in a significant improvement in bending stiffness compared to the addition of CS alone. Importantly, the strength improvement did not sacrifice the density significantly. In summary, the knowledge gained from the current study expands the understanding of strength additives and their relationship with fibres of different surface charge and the overall paper properties. [ABSTRACT FROM AUTHOR]

During the manufacture of low basis weight tissue paper, it is difficult to efficiently use the dry strength agent (DSA) because a large amount of DSA adsorbed fines releases in forming roll by centrifugal forces. In this study, cationic polyvinylamine (C-PVAm) was used as a DSA in an environment where the retention of fines was weak. Addition of C-PVAm to the thermomechanical pulp (TMP) or TMP mixed with softwood bleached kraft pulp (SwBKP) improved the turbidity of filtrate from sheet former, however, the strength of handsheet paper was similar to that without C-PVAm. When C-PVAm was selectively added to SwBKP as much as 4 %, the tensile index could be improved by approximately 10.6 % without changing the retention of fines. In addition, C-PVAm added before the beating of SwBKP showed better results than C-PVAm added after the beating in terms of fines retention, tensile index, and formation. In particular, the tensile index was improved about 7.7 % by adding of C-PVAm 4 % as is before beating of SwBKP. Consequently, it was found that C-PVAm with a high reaction rate can be added before beating of SwBKP to improve the physical strength. [ABSTRACT FROM AUTHOR]

Amphoteric polyacrylamide (AmPAM) is a linear water-soluble polymer that has been applied in papermaking as an agent for flocculation, retention, filtration, and dry-strength improvement. However, AmPAM with different ranges of molecular weight (MW) have different properties in these processes. In this study, a series of AmPAMs were constructed with an anionic monomer, itaconic acid (IA), a cationic monomer, methacryloxyethyl-trimethyl ammonium chloride (DMC), and a main backbone of acrylamide (AM). Four factors influencing free radical polymerization, i.e., reaction temperature, pH, initiator load, and the concentration of monomers, were systematically investigated via an orthogonal test to determine their effects on the MW of AmPAM. Spectroscopy and isoelectric point assays were used to characterize the structure of the produced AmPAM, and the MW was assessed by calculating the viscosity. The reaction temperature had the greatest influence on the MW of AmPAM, followed by the solution pH and the initiator load. To determine the dry strength of papersheets containing AmPAM, the breaking length of handsheets was assessed after adding 0.5% AmPAM (based on fiber) with different MWs. The maximum value, 4.05 km, was 15.0% higher than the control and was obtained using AmPAM with a MW of 330 kDa. [ABSTRACT FROM AUTHOR]

A method (Ankerfors and Lindström in Method for providing nanocellulose comprising modified cellulose fibers, ) was employed to physically attach anionic carboxymethyl cellulose (CMC) chains onto wood pulp, upon which it was fibrillated by a microfluidizer-type homogenizer at high applied pressures and at dilute conditions [<3 % (w/w)]. It was found that the CMC-modified pulp can be fibrillated at the same consistencies as many of the commercially available NFC products. The NFC manufacturing process was also deemed to be energy efficient, as it lacked the need for mechanical pre-treatment, which is often a prerequisite for the production of many existing NFC systems. The CMC-based NFC was studied with respect to the rheological characteristics, and was also characterized using AFM-imaging. Further, The NFC was made into films, and its tensile strength was determined together with its barrier properties. In general, the rheological characteristics (viscosity and storage modulus) together with the tensile strength and oxygen barrier properties of the films were improved with increasing the number of passes through the microfluidizer. The fibrillated CMC-modified pulp was found to be as efficient as other NFC systems when employed as dry strength additive. The employment of the investigated material, which can be produced at acceptable costs and through environmentally benign and industrially relevant processes can, hence, potentially lead to significant future savings in the energy consumption levels in the paper and cardboard manufacturing processes, which have been recognized as major application areas of NFC products. [ABSTRACT FROM AUTHOR]

The oxidation of cellulose nanocrystal (CNC) by sodium periodate can generate aldehyde functions for crosslinking reactions or for further modification, which can extend the range of applications of CNC. In this paper, the effects of reaction conditions during the periodate oxidation of CNC, such as oxidant concentration, pH, temperature and oxidation time on the oxidized CNC yield and the aldehyde content, were investigated and an optimized reaction condition was identified. The generation of aldehyde groups on the CNC was confirmed by Fourier transform infrared spectroscopy analysis, and the decreased crystalline index was observed by X-ray diffraction. The transmission electron microscope observation showed the morphological changes of CNC after the oxidation. The oxidized CNC was used as a strength additive to paper, and the results showed that the dry tensile index was 32.6 % higher than the control sample, and the wet tensile index was reached to 3.08 N.m/g, at the oxidized CNC dosage of 1.2 %. [ABSTRACT FROM AUTHOR]

Corncob, an underutilized agricultural byproduct, was used as the raw material to make a dry-strength additive for paper. Corncob was ground into 80, 100, 150, and 200 mesh powder. The powder was treated with sodium chlorite to remove lignin, and the resulting holocellulose was modified with hydrogen peroxide. The influences of oxidation time, concentration of hydrogen peroxide, dosage of paper strength agent, and the dosage of aluminum sulfate on the paper properties were studied. The results indicate that the oxidized corncobs holocellulose can improve the tensile index, burst index, and folding endurance of paper. Compared with control paper, when the concentration of hydrogen peroxide was 0.9%, the tensile index, burst index, and folding endurance were increased by 24.2%, 14.1%, and 463.8%, respectively. The particle size of raw material, dosage of strengthening agent or aluminum sulfate greatly influences paper properties. Scanning electron microscopy (SEM) analysis showed that the combination between the fibers was improved after adding the strengthening agent, thus improving the strength of the paper. The results can provide a new method for value-added use of corncob. [ABSTRACT FROM AUTHOR]

Highlights: [•] Carboxymethyl cellulose (CMC) was oxidized to form dialdehyde CMC (DCMC). [•] Guanidine hydrochloride (GH) was grafted onto the DCMC to obtain DCMC-GH. [•] The coating of DCMC-GH onto paper resulted in the improvement of paper strength. [•] The DCMC-GH-coated paper exhibited excellent antimicrobial activities. [Copyright &y& Elsevier]

ABSTRACT Biopolymers and their composites were added during the formation of unbleached Kraft bagasse pulp paper sheets to improve the mechanical strength properties of the produced hand sheets. The biopolymers (cellulose, chitosan, and chitosan-cellulose composite) were either crosslinked or noncrosslinked and they were added in series of concentrations from 0.1% to 1.5%. The characterization of the samples using the Fourier transform infrared (IR) technique identified differences in the intensities of the characteristic IR absorption bands for chitosan, cellulose, and their composites, these differences are due to the various degrees of hydrogen bonding. The surface morphology of the biopolymers composites and the treated paper sheets were studied using SEM technique. Both the equilibrium moisture sorption and the diffusion coefficient of the paper sheets containing 1% additives were evaluated at regular time intervals. The long-term stability of the treated paper with biopolymers was verified by exposing the treated and the untreated sheets to hygrothermal ageing. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40761. [ABSTRACT FROM AUTHOR]

The hypothesis has been tested that a carboxymethyl hemicellulose improves more effectively the dry strength of papers than a native hemicellulose. To that end, β- d-glucan from oat was treated with an alkaline ethanolic solution of sodium chloroacetate for different times to obtain a range of carboxymethylated β- d-glucan (CM-glucan) samples. The derivatization was confirmed by Fourier transform infrared spectroscopy and elemental analysis. The physical properties of paper concerning burst and tensile strength as well as folding endurance were essentially improved if CM-glucan was added to unbleached kraft fiber suspension from pine before papermaking. The effects could be maximized by a proper selection of carboxymethylation time and the amount of CM-glucan added to the suspension. The effect was also beneficial in the case of recycled fibers. [ABSTRACT FROM AUTHOR]

new net-cationic polyacrylamide dry strength agent was synthesized through free radical polymerization using acrylamide (AM), itaconic acid (IA), N,N-dimethylacrylamide (F), and sodium methallyl sulfonate (T). Ethylene diamine tetraacetic acid was used as a chelating agent; dimethylaminoethyl methacrylate methyl chloride (DMC) solution was used as a cationic monomer, and ammonium persulfate (APS) was used as an initiator. Orthogonal design and single-factor experiments were utilized to study the effect of many factors, such as reaction time, the ratio of monomers, and the dosage of APS and DMC on the cationic polyacrylamide. The synthesized products were characterized by Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), particle charge detector (PCD), and zeta potential analysis. The results showed that the optimum conditions were as follows: optimal monomer proportion: m(AM):m(IA):m(T):m(F) = 23.79:2.39:0.21:0.32; w (DMC) = 28%; w (APS) = 1.0%, reaction time was 3 hours, reaction temperature was 93 oC, stirring speed was 130 rpm, and reaction pH value was 3.0. The solid content of the polymer was 21.2%. By adding the cationic polyacrylamide to old corrugated container pulp, the tensile index increased by 29.7% and the burst index increased by 66.1%, displaying the obvious enhancement of the paper. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to further evaluate the viability of the integrated pulp mill biorefinery concept. On one side the properties of hot-water pre-extractions were studied, in order to determine the effect of extraction on soda pulping and bleachability. On the other side, the performance of two dry-strength agents on the paper properties obtained from extracted and un-extracted (control) samples were investigated. It was found that hemicelluloses removal of the depithed bagasse chips was 24.6% at 140°C for 10min with a solid to liquor ratio (S:L) of 1:8 (w/w), and that mass removal increased with extraction time and temperature. The hemicelluloses removal reached 65.5% at 170°C for 30min. The residual extracted bagasse were subjected to soda pulping at 160°C for 1h with 11, 14 and 17% active alkali charge and a S:L of 1:5 (w/w). Conventional elemental chlorine free bleaching (D 0 ED 1) sequence was also used to compare the results with the un-extracted ones. Compared with the control sample, the overall pulp yield for extracted bagasse increased considerably while Kappa number and rejects decreased moderately. In addition, yield and Kappa number of the pulps improved with increasing alkali charge from 11% to 17%. After pre-extraction, better brightness compared with the control pulp was also shown. However, hot-water extraction was found to negatively impact some pulp properties including decreases in burst and tensile indices while addition of chitosan and cationic starch could improve the strength properties. Overall, papers treated with chitosan gave superior mechanical properties compared to the papers treated with cationic starch. [Copyright &y& Elsevier]

Abstract: The objective of this study was to evaluate the ability of molasses, a low cost by-product of the sugarcane extraction, for improvement of the physicomechanical properties of old corrugated container (OCC) recycled paper as a dry-strength agent. The influence of fiber beating on the enhancing effect of molasses was also investigated. Five dosages (0%, 5%, 10%, 15%, and 18%) of molasses and 3 levels of freeness (420, 400, and 320mL CFS) were used as variable factors. For each treatment, 6 handsheets, each having an area of 200cm2 and basis weight of 120g/m2, were made. The experimental results showed that except for the case of tear index, the increase in mechanical and physical properties were considerably higher than control (untreated) samples. Significant changes of tensile and burst indices, breaking length, and air resistance were observed after the addition of 18% molasses. From a statistical viewpoint, the addition of molasses had more positive effects on the above-mentioned properties, compared to the fiber beating. However, at a certain dosage of molasses, with increased beating, the strength properties were improved remarkably. This is due to the molasses adsorption efficiency, which depends on the specific surface of particles. The water retention values (WRV) were moderately increased by applying molasses, however with increasing dosage the WRV was improved. From these findings, it is concluded that molasses is a promising dry-strength agent and it can also be used as a replacement for cellulosic fibers. This conclusion is in good agreement with the previous research articles, which introduced molasses as a new additive in papermaking. [Copyright &y& Elsevier]

Cationized birch xylan was prepared and its use as a papermaking chemical was evaluated. The focus was on studying the effects of cationized birch xylan on the wet and dry strength of fine paper. The results of the laboratory experiments show that the addition of 3 percent of cationized birch xylan to birch kraft pulp improved the initial wet strength of the web by 30 percent compared to base stock at a solids content of 55%. Furthermore, the tensile stiffness of the wet web increased by approximately a third and the dry tensile strength improved by 26%, while the dry elastic modulus was not changed. The improvements in the strength properties were clear when compared to the base stock, but not as high as achieved with conventionally used cationized starch. The difference between the xylan and starch is most likely due to the shorter polymer chain length of the cationized xylan. [ABSTRACT FROM AUTHOR]

A novel method was developed for the determination of linting propensity of paper based on printing with an IGT prlntabillty tester and image analysis of the printed strips. On average, the total fraction of the surface removed as lint during printing is 0.01%-0.1%. This value is lower than those reported in most laboratory printing tests, and more representative of commercial offset printing applications. Newsprint paper produced on a roll/ blade former machine was evaluated for linting propensity using the novel method and also printed on a commercial coldset offset press. Laboratory and commercial printing results matched well, showing that linting was higher for the bottom side of paper than for the top side, and that linting could be reduced on both sides by application of a dry-strength additive. In a second case study, varying wet-end conditions were used on a hybrid former machine to produce four paper reels, with the goal of matching the low linting propensity of the paper produced on a machine with gap former configuration. We found that the retention program, by improving fiber fines retention, substantially reduced the linting propensity of the paper produced on the hybrid former machine. The papers were also printed on a commercial coldset offset press. An excellent correlation was found between the total lint area removed from the bottom side of the paper samples during laboratory printing and lint collected on halftone areas of the first upper printing unit after 45000 copies. Finally, the method was applied to determine the linting propensity of highly filled supercalendered paper produced on a hybrid former machine. In this case, the linting propensity of the bottom side of paper correlated with Its ash content. [ABSTRACT FROM AUTHOR]

Hydrophilic natural and synthetic organic substances, which have emphatical affinity with pulp fibers are used for improving the dry strength properties of paper. The study was carried out with secondary fiber material (SFM) from newspapers and neutrally sized offset printing paper. Paper samples were prepared in laboratory conditions from an anionic direct dye, a sizing agent based on alkyl ketene dimmer (AKD), a filler and a cationic low molecular mass Dry Strength Resin (DSR). At constant AKD (1 %, 2 %, 3 % as a commercial product) consumption, the DSR quantity was varied (0.1 %, 0.2 %, 0.3 % of oven dry fibers (o.d.f.). The cationic DSR is appropriate for producing neutrally-sized papers containing recycled fibers with CaCO3 as a filler. It contributes to filler retention and sizing, and the improves strength properties of paper. It is observed that with increasing the DRS consumption the color of the paper becomes darker. [ABSTRACT FROM AUTHOR]

The function of water in the adhesion between wet cellulose fibers both in the assembly of papers and the establishment of the properties is discussed. The contributions of friction and hydrogen bonds are reviewed, together with the new concept of interfiber ordered water structure created by the hydrophilic surfaces of the fibers. Procedures for the enhancement of interfiber adhesion are summarized in terms of the accessibility, the stereotopochemistry and the enthalpies of the interacting moieties on contiguous surfaces. [ABSTRACT FROM AUTHOR]

The influence of polymer characteristics on paper properties has not been well understood. In this work, we aimed at analyzing the performance of various cationic-modified poly vinyl alcohols (CPVA), as dry strength additives, on the properties of high-yield pulp (HYP). Various dosages of CPVA having different molecular weights (MW) and charge densities were applied on HYPs, and the resulting paper properties were evaluated. Also, an atomic force microscope (AFM) was employed to evaluate the attraction/repulsion force developed between modified fibers and AFM probes. Our results showed that the hydrophilicity and contact area of fibers were increased via CPVA application. High MW CPVA with the charge density of 0.7 meq/g was the most effective one in improving the properties of the fiber networks made from HYPs. The changes in the fiber morphology and chemistry played roles in improving the properties of fiber networks. The introduction of similar charges on HYPs via applying various dosages of different CPVAs confirmed that the changes in the fiber chemistry were not the only dominant factor in improving the properties. Additionally, the significance of polymer bridging (polymer characteristics) on the network properties was hindered due to the presence of fines in the HYP. [ABSTRACT FROM AUTHOR]

Surprisingly the strength of wet paper is still poorly understood. Here we show that the traditional explanation of the strength of wet paper is incorrect. Observations that the capillary force in fiber crossings in wet paper approaches zero as the water is evaporated show that they are not responsible for the strength of wet paper. Instead we present evidence that fiber entanglements and friction are the cause. Like paper, films made of nanotubes, nanorods, nanofibers or nanoribbons also consist of randomly oriented fibers, and this field may well benefit from an increased knowledge of paper properties. [ABSTRACT FROM AUTHOR]

High-yield pulp (HYP) is gaining increasing interest in wood-free papers, because it can improve the bulk, formation, and opacity of papers. However, one of the challenges for the papermakers is the strength of papers when a large amount of HYP is replaced with hardwood kraft pulp. In this work, we explored the potential of using cationic-modified polyvinyl alcohol (C-PVA) in increasing the strength properties of HYP. Also, C-PVA was applied to the paper-sheets made of softwood/hardwood bleached kraft pulps (SBKP/HBKP) and HYP under various conditions, and the corresponding paper properties were evaluated. It was observed that C-PVA increased the strength properties of these paper-sheets, and the results obtained from using C-PVA were only slightly less effective than those obtained from using cationic starch (C-starch). Furthermore, the addition of C-PVA to HYP, and subsequently mixing with the blend of SBKP/HBKP (option no. 1) improved the tensile and burst indices, light scattering coefficient and apparent density of paper-sheets more significantly than did the addition of C-PVA directly to the mixed furnish of SBKP/HBKP/HYP (option no. 2). Additionally, atomic force microscope (AFM) analysis showed that the attraction force, developed between the AFM-tip and the fiber surface, was changed by the C-PVA modification. The tensile and burst indices of paper-sheets were improved by adding 10 mg g-1 C-PVA and substituting 30% of HYP for HBKP, whereas the tear index, apparent density, PPS-roughness, and brightness decreased. [ABSTRACT FROM AUTHOR]

In this study, the impact of soda−air−anthraquinone (AQ) pulping conditions on delignification and silica precipitation onto pulp fibers and paper sheets was studied. The results showed that the yield and silica precipitation slightly increased upon application of AQ in soda−air pulping. Scanning electron microscopy (SEM) and elemental analysis confirmed the deposition of silica-related particles on fibers and on paper sheets for both soda−air and soda−air−AQ pulping. Furthermore, increasing the cooking temperature had a stronger impact on delignification and silica deposition than did increasing the cooking time for soda−air−AQ pulping. In another set of experiments, the influence of cationic poly(vinyl alcohol) (CPVA) with two different molecular weights on improving the strength properties of straw pulps produced under various soda−air−AQ pulping conditions was studied. The adsorption of CPVA onto straw pulp and its effect on silica retention for paper sheets were comprehensively investigated. [ABSTRACT FROM AUTHOR]

Abstract: The influence of operational variables in the pulping of vine shoots by use of ethylene glycol [viz. temperature (155–185°C), cooking time (30–90min) and ethylene glycol concentration (50–70% v/v)] on the properties of the resulting pulp (viz. yield, kappa number and viscosity) and paper sheets (breaking length, stretch, burst index, tear index and brightness) was studied. A central composite factorial design was used in conjunction with the software ANFIS Edit Matlab 6.5 to develop fuzzy neural model that reproduced the experimental results of the dependent variables with errors less than 5%. The model is therefore effective with a view to simulating the ethylene glycol pulping process. [Copyright &y& Elsevier]

AbstractThe polysaccharide xyloglucan as a wet-end additive improves paper properties. In the present study, paper strength improvement was analysed for dry handsheets made from chemical, mechanical and recycled pulps coated with xyloglucan in a spray application. Results are compared with sheets made from the same pulps treated with xyloglucan in the wet-end. Kraft pulp handsheets of bleached hardwood and softwood showed significant improvements of tensile, tear and Z-strength by xyloglucan spray treatment versus wet-end application, whereas handsheets of de-inked and thermomechanical pulp were improved only slightly. In both wet-end and spray applications, the effect of xyloglucan addition was intimately related to the presence of non-cellulosic components on the fibre surface. Further strength improvements were obtained for chemical pulps by addition of borax to the spray solution, which were likely to be due to the formation of borate-mediated xyloglucan cross-links. Spray coating of xyloglucan, with or without borax, thus represents a potential new application of this polysaccharide to increase paper dry strength. [ABSTRACT FROM AUTHOR]

It has been speculated in several studies that lignin would impair interfiber bonding when present on the fiber surface due to the hydrophobic nature of lignin. Several experiments were devised in the present study to compare the internal bond strength and specific bond strength of pulp fibers with different surface lignin concentrations. The pulp samples used included unbleached and fully bleached kraft pulp, CTMP pulp with different middle lamella coverage on the fibers, and fully bleached pulp with lignin adsorbed on the fiber surface. With all of the pulp samples used, the internal bond strength was reduced markedly when lignin was present on the fiber surface; but the relative bonded area was not affected significantly. [ABSTRACT FROM AUTHOR]

Abstract: This work focused on studying the dependence of paper sheet strength properties on the composition of additives, namely chitosan, cyanoethyl and carboxymethyl chitosan. Chitosan and its derivatives enhanced the strength properties of unagged and aged paper sheets. Also, cyanoethyl chitosan improved the dielectric properties of the treated paper sheets. The dielectric study was carried out over a frequency range from 100Hz to 100kHz at temperature range from 20 to 140°C. The variations of permittivity ε′ versus the cyanoethyl chitosan content at three different temperatures show the highest dielectric properties at cyanoethyl chitosan of 0.3%. The variation of ε″ versus the applied frequency was fitted by a superposition of Fröhlich and Havriliak–Negami functions in addition to the conductivity term. These functions could be ascribed by the Maxwell–Wagner effect and the orientation of the large aggregates formed by the addition of chitosan to the paper sheet. [Copyright &y& Elsevier]

This article presents the author's views on paper conservation. In the conservation of paper, gamma irradiation has been used for several specific purposes. Its application is based on the high penetration power of gamma rays and their high energy. Gamma irradiation has been used for the destruction of various fungi on several types of paper. High energy irradiation causes excitation and ionization leading to the degradation of the molecules and the creation of free radicals. The accompanying structural changes are in many respects analogous to those observed when cellulose is oxidized, finally resulting in the loss of tensile strength, reduced degree of polymerization and an increase in the number of carboxyl and carbonyl groups.

This article presents the author's views on the effect of relative humidity on the degradation rate of cellulose. The kinetics of acid hydrolysis of cellulose described by researcher A. Ekenstam and called the Ekenstam equation was investigated using some samples of lignin-free paper. The dependence of rate constant against relative humidity has been determined at 90 degree centigrade. It was found that it was safe to use saturated solutions of salts consisting of an alkali metal and a halogen ion. Deposits of these salts on the cellulose did not affect its degradation rate, in contrast to magnesium chloride, which significantly accelerated the degradation process.

This article presents the author's views on paper conservation using aqueous solutions of calcium hydroxide and methyl cellulose. Using solutions of calcium hydroxide results in a higher alkaline reserve compared to treatments using aqueous solutions of calcium bicarbonate, magnesium sulphate or magnesium bicarbonate, respectively. The level of the alkaline reserve in paper was found to be dependent upon the calcium hydroxide content in the solution and the length of treatment. It was also found that paper treated with calcium hydroxide had increased folding endurance and retained its alkaline reserve better after ageing.

This article presents the author's views on the non-destructive method for alkaline reserve determination in paper. Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) is a used for measuring the concentration of ionic substances deposited on cellulosic substrates. The advantages are that it is quite sensitive within the medium infrared range, where ionic inorganic compounds such as sulphates, nitrates, phosphates, silicates arid carbonates absorb strongly. Application of DRIFTS technique to paper is very quick and simple. Measurement of spectra does not require special preparation, and a complete analysis of a book or a document can be accomplished within an hour.

This article presents the author's views on gelatine in historical paper production and as inhibiting agent for iron-gall ink corrosion on paper. During the early days, as a sizing agent hide glue, or gelatine was used, applied by soaking. This form of size and method of application was almost exclusively used until the invention of machine made paper and pulp or internal sizing at the beginning of the 19th century. Two main reaction mechanisms cause the damage that threatens documents written in iron-gall ink. They are acid hydrolysis of cellulose, and oxidation of cellulose, rapidly catalysed by transition metal ions.

Considerable differences will be found between the way many art works and particularly the papers, which act as support and made especially for graphic art, have aged over the years. They confirm an urgent need to use permanent archival materials to ensure the longevity of an art work. To evaluate whether some of papers used by artists are likely to last the test of time it is necessary to determine their permanence and durability. A work of art on paper, such as a print, created for display as the artist intended, should be printed on paper of archival quality, displayed and stored, when not being exhibited, under strictly controlled climatic conditions, with strict light levels.

Two terms, permanence and durability are often used to express the ageing behavior of paper. Permanence relates to the retention of a paper's mechanical properties over prolonged periods, while durability expresses the degree to which a paper retains its original qualifies under continuous usage. Usually, strength and optical properties are important in most papers in which permanence is to be studied. Paper strength depends upon fiber strength and the strength of intermediate bonds, the latter being the more critical, but the significance of fiber strength in the resulting paper strength cannot be neglected.

Presents a study which investigated whether the non-reducing disaccharide trehalose can have a protective effect on paper by inhibiting oxidative degradation and hydrolysis reactions of cellulose, which cause a rapid decrease in the mechanical resistance of paper. Materials and methods; Results; Conclusions.

Abstract: Cationic starch (CS) is routinely used in the papermaking process to improve the dry strength or printability of paper. The effectiveness depends on the distribution of the starch on the pulp fiber, and in this study, time-of-flight secondary ion mass spectrometry was used to investigate this distribution. The characteristic peak at 58m/z was applied to map the CS. Based on the imaging analysis of the handsheets with the CS as an internal additive, the distribution of CS became more uniform with decreasing freeness. The amount of adsorbed CS increased with increasing fiber length and was lower on vessels than on other fibers. These results were related to fibrillation. From the analysis of handsheets with CS as an external additive, the penetration depth of the starch into base paper increased with decreases in the sizing degree of the base paper. [Copyright &y& Elsevier]

Corrections to the article "Wrinkling of a Stretched Thin Sheet" that was published in the 2011 issue is presented.