Bleached Kraft Pulp Research Articles

Evaluation of the Physical Properties of Unbleached Kraft Pulp Produced from Persimmon Byproducts

This study examined the features of unbleached kraft pulp produced from persimmon byproducts (PB-UKP), which can be used to replace commercial kraft pulp. PB-UKPs prepared through the kraft pulping laboratory process were beaten to 500 and 400 mL CSF. Their fiber properties were subsequently analyzed and compared with those of commercial hardwood bleached kraft pulp (Hw-BKP). The physical properties of handsheets made from PB-UKP and Hw-BKP with a grammage of 60 g/m² were also evaluated.BRPB-UKP and Hw-BKP exhibited similar initial fiber properties. However, after beating, the fiber length of PB-UKP was longer than that of Hw-BKP, and the fines content of Hw-BKP increased considerably. Moreover, no noticeable difference was observed in the fiber width of the pulp. As the beating time increased, sheet bulk decreased, and the sheet strengths increased. The tensile and burst strengths of the handsheet made from PB-UKP were higher than those made from Hw-BKP at a similar sheet bulk because PB-UKP had a higher long fiber content. Thus, PB-UKP could be used as a colored raw material to manufacture paper products.

Evaluation of the Physical Properties of Carboxymethylated Cellulose Nanofiber Derived from Red Algae Pulp

This study investigated the utility of red algae bleached pulp (RaBP) as a raw material for producing carboxymethylated cellulose nanofiber (CM-CNF). Hardwood bleached kraft pulp (HwBKP) was used as control. Two types of carboxymethyl celluloses (CMCs) made from RaBP and HwBKP, respectively, were prepared according to the degree of carboxymethylation (CM), while considering the sodium hydroxide and chloroacetic acid dosage: low and high CM. Furthermore, the fiber morphology and charge density of the CMCs were evaluated to verify the carboxymethylation reaction. The final CM-CNFs produced from CMCs were ground for five passes using a microgrinder, and their fiber width, low-shear viscosity, and zeta-potential were analyzed.BRMorphology of CMCs revealed that the fibers were swollen and dissolved in water to produce transparent fibers. The charge density of the CMCs increased with increasing chemical dosage. When comparing CMCs according to species, the fiber size and charge density of CMC made from RaBP showed lower values than HwBKP. As the chemical dosage increased, fiber width and zeta-potential of CM-CNFs decreased, and their low-shear viscosity increased. The CM-CNFs made from RaBP had a lower fiber length and zeta-potential than those made from HwBKP. Therefore, RaBP can be potentially used to manufacture small and anionic CM-CNF by combining a carboxymethylation pretreatment and micro grinding.

Copy Paper from Recycled Egg Cartons – A 12-inch Paper Machine Development Study

The presented research project describes the development of a copy paper product from recycled egg carton fiber material. The development included laboratory handsheet development and machine-made paper product produced on a 12-inch (304 mm) wide laboratory Fourdrinier paper machine which was operated at a speed of 6.4 ft/min (1.95 m/min).
 The final machine-made paper had a recycled egg carton fiber content of 70% and 30% content of northern bleached softwood Kraft fiber as reinforcement fiber material to avoid sheet breaks on the laboratory Fourdrinier paper machine. The produced machine-made paper appeared to be visibly brighter to the eye with the addition of the northern bleached softwood Kraft pulp compared to paper without softwood fibers. Printing tests using an office type laser printer showed good results.
 The produced machine-made paper had a basis weight of 81 g/m² and a solids content of 99.27%. After conditioning at a temperature of 23°C ± 1°C and a humidity of 50% the basis weight increased to 92.13 g/m², with a caliper of 186 μm. The tensile index and tear index was 93.20 Nm/g and 9.78 mN/gm² respectively, opacity measured 96.52%, and brightness measured at 37.09%.
 It was observed that REC pulp fiber material can absorbs more moisture during conditioning which leads to increased basis weight and thickness due to swelling of the fiber material.

Assessment of the Performance of Cationic Cellulose Derivatives as Calcium Carbonate Flocculant for Papermaking.

Cationic polyacrylamides (CPAMs) are usually used as filler retention agents in papermaking formulations. However, increasing environmental restrictions and their non-renewable origin have driven research into bio-based alternatives. In this context, cationic lignocellulosic derivatives have been attracting considerable research interest as a potential substitute. In this work, distinct cationic celluloses with degrees of substitution of between 0.02 and 1.06 and with distinct morphological properties were synthesized via the cationization of bleached eucalyptus kraft pulp, using a direct cationization with (3-chloro-2-hydroxypropyl) trimethylammonium chloride (CHPTAC) or a two-step cationization, where the cellulose was first oxidized to form dialdehyde cellulose and was then made to react with Girard’s reagent T (GT). Fibrillated samples were produced by subjecting some samples to a high-pressure homogenization treatment. The obtained samples were evaluated regarding their potential to flocculate and retain precipitated calcium carbonate (PCC), and their performance was compared to that of a commercial CPAM. The cationic fibrillated celluloses, with a degree of substitution of ca. 0.13–0.16, exhibited the highest flocculation performance of all the cationic celluloses and were able to increase the filler retention from 43% (with no retention agent) to ca. 61–62% (with the addition of 20 mg/g of PCC). Although it was not possible to achieve the performance of CPAM (filler retention of 73% with an addition of 1 mg/g of PCC), the results demonstrated the potential of cationic cellulose derivatives for use as bio-based retention agents.

E. Globulus Vessel and Fibre Chemical Analysis

Hardwood species have a complex cellular structure consisting of fibres, vessel elements and parenchyma cells with different chemical compositions. However, the presence of vessels with significant dimensions in their structure is a recurrent problem in the operation of industrial UWF paper printing. Since the 1980s, vessel picking and ink refusal are problems that paper professionals have tried to solve, but solutions for these have not yet been fully found. If vessels are concentrated in a stream, they can be pre-treated (e.g., by mechanical refining) and reincorporated into the pulp. Other strategies aim at vessel enzymatic and/or chemical passivation and sheet surface chemical treatment, altering the vessel adhesion to the fibre network. This requires vessel concentration at laboratorial level for proper chemical studies, such as FE-SEM, μ-XPS, TOF-SIMS and μFTIR. The main objective of our experimental study was to examine bleached kraft pulp E. globulus vessel and fibre composition. For this we performed EDX and μ-FTIR analysis on both fibre and vessel elements, and obtained the carbohydrate composition, the total acids content, the hexenuronic acids content and the zeta potential.
 Keywords: E. globulus, vessel, EDX, μ-FTIR, sugar content, zeta potential

Oxidation treatments to convert paper-grade Eucalyptus kraft pulp into microfibrillated cellulose

Microfibrillated cellulose (MFC) is an emerging cellulosic material that has shown enormous potential in various industrial sectors such as food packaging, cosmetics, pharmaceuticals, filler for cement and paper, and others. Yet, there is still the need to improve its processing in order to reach its full potential. Despite research efforts for the production of MFC, the production volumes remain low because the costs of these products are hardly competitive with synthetic polymers. The present study investigates the conversion of bleached Kraft pulp into MFC using three different oxidative treatments: (1) oxidation with sodium periodate followed by oxidation with hydrogen peroxide to enrich the pulp with carboxyl groups; (2) activation of hydrogen peroxide with copper to produce hydroxyl radicals; and (3) use of hydrogen peroxide alone in alkaline medium. Treatments (1) and (2) allowed producing interesting MFC with reduced energy consumption.

Unusable cotton spinning mill waste: A viable source of raw material in paper making

Since the reserves of natural renewable resources are being inexorably diminished, the utilization of the recoverable waste in new area is gaining global attention day by day. Besides, as the cost of raw materials constitutes the majority of a production cost, the usage of undesirable but inevitable processing waste in the manufacturing process provides a considerable advantage to the manufacturers. Herein, it has been attempted to exploit unusable cotton spinning mill waste (filter waste derived from humidification plant) to convert it into paper. Handsheets of 70 g/m2 and 80 g/m2 were successfully produced from 100% cotton waste, 100% bleached cotton waste, and blends of bleached cotton waste with bleached hardwood kraft pulp (HWKP) (HWKP is typically used to produce commercial-grade papers). Morphologies and mechanical properties of handsheets were thoroughly investigated by whiteness index, brightness%, breaking length, tear index, bursting index, FTIR spectroscopy, optical microscope, and scanning electron microscope. Based on detailed observations, it is summarized that the produced handsheets, depending on the chemical treatment and blend ratio with HWKP, possess variations in appearances and properties that will have a wide range of potential applications from newsprint, tissue paper to commercial-grade writing and printing papers.

Alkalization of Kraft Pulps from Pine and Eucalyptus and Its Effect on Enzymatic Saccharification and Viscosity Control of Cellulose.

Bleached kraft pulps from eucalyptus and pine were subjected to cold caustic extraction (CCE) with NaOH (5, 10, 17.5, and 35%) for hemicelluloses removal and to increase cellulose accessibility. The effect of these changes was evaluated in enzymatic saccharification with the multicomponent Cellic CTec3 enzyme cocktail, and in viscosity reduction of pulps with the monocomponent Trichoderma reesei endoglucanase (EG). After CCE with 10% NaOH (CCE10) and 17.5% NaOH (CCE17.5), hemicellulose content lower than 1% was achieved in eucalyptus and pine pulps, respectively. At these concentrations, cellulose I started to be converted into cellulose II. NaOH concentrations higher than 17.5% decreased the intrinsic viscosity (from 730 to 420 mL/g in eucalyptus and from 510 to 410 mL/g in pine). Cellulose crystallinity was reduced from 60% to 44% in eucalyptus and from 71% to 44% in pine, as the NaOH concentration increased. Enzymatic multicomponent saccharification showed higher glucose yields in all CCE-treated eucalyptus samples (up to 93%) while only CCE17.5 and CCE35 pine pulps achieved 90% after 40 h of incubation. Untreated bleached pulps of both species presented saccharification yields lower than 70%. When monocomponent EG was used to treat the same pulps, depending on enzyme charge and incubation time, a wide range of intrinsic viscosity reduction was obtained (up to 74%). Results showed that eucalyptus pulps are more accessible and easier to hydrolyze by enzymes than pine pulps and that the conversion of cellulose I to cellulose II hydrate only has the effect of increasing saccharification of CCE pine samples. Viscosity reduction of CCE pulps and EG treated pulps were obtained in a wide range indicating that pulps presented characteristics suitable for cellulose derivatives production.

Effects of pretreatments on the solubilization and theoretical methane production of waste activated sludge from a Brazilian eucalyptus kraft pulp mill

Waste activated sludge (WAS) originating from kraft pulp mill effluent treatment plants represents an important environmental challenge for this industry. Anaerobic digestion is a promising option for WAS treatment, with the added benefit of biogas production. This paper presents the application of thermal, thermal-alkaline, and mechanical pretreatment methods in order to promote the solubilization of organic matter to enhance the anaerobic digestion of the WAS from a Brazilian Eucalyptus bleached kraft pulp mill. A total of 16 pretreatment operating conditions were compared. Chemical analyses showed an improvement in organic matter solubilization, with an increase greater than 7-fold for soluble chemical oxygen demand and 4-fold for biochemical oxygen demand. Nutrient solubilization showed an increase greater than 10-fold for total Kjeldahl nitrogen and 3-fold for total phosphorus. Theoretical biochemical methane potential was improved from 211 mLCH4/gVS for raw sludge to 333-343 mLCH4/gVS after mechanical pretreatment, 314-360 mLCH4/gVS after thermal pretreatment, and 373-378 mLCH4/gVS after thermal-alkaline pretreatment. In general, thermal-alkaline pretreatment showed the best results for all the evaluated parameters, with the advantage of requiring lower temperature and retention time when compared to thermal conditions.

Rewet suppression through press felt engineering

Due to the immense energy and associated financial cost of drying paper, achieving a drier web entering the dryers is a key objective in paper manufacture. One major research thrust has been finding a way to increase press solids by mitigating or eliminating rewet in the press section. For decades, solutions to this problem have remained elusive. In this work, we develop a novel approach that significantly reduces rewet by rupturing the liquid channels between felt and web. We illustrate the effects that altering the mechanical and surface properties of the press felt matrix have on the stability of these liquid channels. In a laboratory-scale platen press, a 40% reduction in the residual water of 120 g/m2 southern bleached softwood kraft (SBSK) pulp handsheets after pressing was observed, corresponding to an increase in press solids from 48% to 61%. For reference, pressing under identical conditions with paper blotters, in which minimal rewet is presumed to occur, resulted in 64% solids. Furthermore, we observed enhanced dewatering across a range of basis weights, applied pressures, and felt types. In addition to measuring the solids content of pressed sheets, we capture and analyze video evidence of the mechanisms at play in our improved dewatering technology.

"EFFECTS OF SURFACTANT APPLICATION ON ACACIA HYBRID KRAFT PULP PROPERTIES"

"Acacia hybrid kraft pulping, with the addition of different non-ionic commercial surfactants, as well as its subsequent elemental chlorine free (ECF) bleaching, was studied. The characteristics of bleachable pulps made by conventional kraft and by kraft-surfactant pulping methods were investigated. The results revealed that the type and dosage of the surfactants during the production of Acacia hybrid kraft pulp had no significant influence on the kappa number, screen yield, and reject. On the other hand, the extractive content and brightness of Acacia hybrid bleached kraft pulp were considerably affected by the types and dosages of surfactants used. The addition of 0.1% LAE (linear alcohol ethoxylate) on oven-dried chips lowered the extractive content by 58.20%, whereas 0.125% PEG (polyethylene glycol esters of fatty acids mixed with block copolymer of ethylene oxide with propylene oxide) on oven-dried chips reduced the brightness by 2.78%. Furthermore, the addition of surfactants had no discernible effect on the specks of dirt."

RECYCLING OF WET-STRENGTH TISSUE PAPER. PART 2. BASIC PROPERTIES OF SECONDARY FIBERS

The present investigation focuses on morphological characteristics, tensile and optical properties of secondary fibers obtained in various conditions of batch low-consistency repulping process for wet-strength tissue paper with 100% of bleached softwood kraft pulp. It was found that length-weighted fiber length and fiber width values as well as fiber length and fiber width distributions remained almost unchanged regardless of the repulping time and the presence of persulfates. The shortened repulping cycle due to the use of persulfates lead to an increase in the shape factor from 83.0% to 84.1–84.4%, decrease in the number of fiber kinks from 0.84 to 0.72–0.74 and an increase in zero-span tensile strength of recycled handsheets by 10–12%. At the same time, the shortened repulping cycle resulted in increase in the coarseness of secondary fibers from 190 mg/m to 230–235 mg/m leading to a slight increase in the bulk of the paper and a decrease in its internal bond strength by an average of 8%. The use of persulfates during wet-strength tissue paper repulping improves the color of recycled handsheets and its brightness by up to 3%.

Addition of polyvinylamine in chemi-thermomechanical pulp and kraft pulp and the effects on dewatering, strength, and air permeance

The addition of polyvinylamine (PVAm) in the wet-end of the papermaking process was investigated. The changes in pulp drainage, vacuum dewatering, tensile strength, and air permeance were measured with and without PVAm. Both chemi-thermomechanical pulp (CTMP) and bleached kraft pulp were used. The dewatering and drainage abilities of the different pulps was examined by measuring the dewatering resistance (°SR), the water retention value (g/g), and the vacuum dewatering. The tensile strength and air permeance values were tested on paper sheets. The results showed that the initial dewatering was faster for pulps with PVAm, and this effect was greater for the CTMP and at higher basis weights. The strength increased when PVAm was added but only if the pulp was washed before sheet forming. The unwashed pulp with PVAm had worse formation, which resulted in lower tensile strength values. The air permeance of the sheets was higher with the addition of PVAm, primarily as a result of higher flocculation. Adding PVAm to the stock suspension in the wet-end of the paper machine has great potential for end-products that require high air permeance and tensile strength properties. PVAm could also act as a dewatering enhancing agent, but caution must be taken regarding the potential of formation problems.

Dissolution of HwBKP with [Bmim]Cl-DMF Solvent and Production of Cellulose Beads: Effect of Mixing Ratio of Solvents

Hardwood bleached kraft pulp (HwBKP) was dissolved with 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) and N,N-dimethylformamide (DMF) at 110℃, and cellulose beads were prepared by dropping the [Bmim]Cl/DMF/cellulose solution into water. The effects of the mixing ratio of [Bmim]Cl and DMF on the properties of the cellulose solution and beads are investigated in this paper. Increasing the DMF ratio decreased the viscosity and surface tension of the cellulose solution. Moreover, all cellulose solutions with various mixing ratios of [Bmim]Cl and DMF showed shear thinning behavior. The cellulose beads with 800-1500 μm diameters were prepared by varying the mixing ratio of [Bmim]Cl and DMF (the cellulose concentration was 3%; the inner diameter of a syringe needle was 0.41 mm). Increasing the DMF ratio increased the particle size of the cellulose beads, and increasing this ratio over 40% created a rough surface on the beads. During dissolution with [Bmim]Cl and DMF and regeneration in water, the cellulose crystal structure was changed to cellulose II and the crystallinity of the cellulose decreased. In addition, the thermal stability of the cellulose beads was slightly lower than that of the HwBKP.

Organosolv Pulping of Hemp Stem for a Potential Papermaking Pulp

Glycol ether-based organosolv pulping process was applied to hemp stem to identify a possible sustainable source for papermaking. The hemp organosolv pulps were produced by controlling the content of glycol ether with water, ranging from 30% to 90% at a fixed cooking temperature, time, and acid catalyst. Hardwood bleached kraft pulp (HwBKP) was used as a reference. In this study, the hemp stem including the bast and core consisted of 33.9% of α-cellulose and 36.7% of hemicellulose. The length-weighted length of the organosolv hemp pulp was 0.5-0.8 mm, which was similar to HwBKP. Morphology of organosolv hemp pulps was fibrillated higher than the HwBKP, resulting in a high tensile index in handsheets. In addition, the air permeability of handsheets of the organosolv hemp pulps increased with the increase of the glycol ether contents in pulping conditions.

The effect of pulp type on the performance of microfibrillar lignocellulosic bismuth-based active packaging material

AbstractThe study aims to investigate the effect of the different lignocellulosic pulp on the composite properties for active packaging application. Microfibrillated cellulose from bleached and unbleached Kraft and thermomechanical pulp (TMP) having different cellulose, hemicellulose, lignin, and extractive content were used as the matrix phase with antimicrobial bis-phosphinato bismuth complex as the dispersed phase. The Kraft pulp has thinner fibres as observed in the SEM images and have higher aspect ratio (EMT 109–157) compared to TMP (EMT 43–51). So, it is more easily fibrillated resulting in a strong close network and therefore resulting in low water vapor transmission rate (WVTR) and high tensile index (20–91 g/m2.day and 59–78 Nm/g respectively) compared to the TMP ones (153–261 g/m2.day and 35–43 Nm/g respectively). While the physical dimension of the fibres controls the mechanical and barrier properties, the leaching and antibacterial performance is related to the bonding of the complex with the matrix. The high hydrophilicity of the bleached kraft pulp results in a weak bond with the hydrophobic bismuth complex, easing its release to kill the surrounding microbial population and thus resulting in larger zones of inhibition against both Gram-positive and Gram-negative bacteria. Therefore, bleached kraft pulp was found to be the most suitable with promising barrier, mechanical and antibacterial properties.

METHODS OF PREPARATION OF NANOFIBRILLATED CELLULOSE FOR SPECIAL FILTER PAPERS WITH EFFECTIVE AIR FILTRATION. SHORT NOTES

Nanofibrillated cellulose was prepared from distillery refuse based on maize starch using the extraction with NaOH and HCl involving centrifugation. SEM images of bleached kraft pulp with/without the addition of nanofibrillated cellulose were compared. Theresults showed that the application of nanofibrillated cellulose caused a visible reduction in the surface porosity. Conversely, mixing of the pulp with the nanofibrillated cellulose resulted in large pores among the fibres. The effect of the cationic retention aid on porosity was not significant, observed in the fines retention. A minimal difference in porosity was found among of fine and coarse fibres.When lyophilisationas drying method was used it yielded nanofibrillated cellulose with a size in the range of approximately 100 to 150 nm.

Beverage Coaster Paper - A Protective Paper Grade Development

Beverage coaster paper represents a specialty paper grade, which has its origin in the late 1880s. Its primary function is to serve as a barrier between the beverage and the table surface by soaking up the condensing water of the cold beverage and protect the wooden table surface as well as the customer from droplets of the condensing water.
 A beverage coaster grade was developed utilizing thermos mechanical pulp, bleached softwood and bleached hardwood Kraft pulp. Manufactured on a 48-inch (1219 mm) wide small commercial Fourdrinier paper machine with an oven dry basis weight basis weight of 473.6, and thickness of 886 µm.
 The water absorbance achieved a value 784 g/m² for the top side and 693 g/m² for the wire side of the paper. The smoothness value was 2734 ml/min for the top and 2784 ml/min for the wire side
 The burst index was measured at 0.56 kPa*m²/g, a tear index of 14.68 mNm²/g for the machine direction and 10.78 mNm²/g for the cross machine direction.
 The manufactured beverage coaster paper had no visible signs of dirt and a yellowish white color, an opacity a value of 100%, a brightness of 79.14% and a whiteness of 54.76%. The yellowish white colour had an 95.24% value for the L*, -1.62 for the a*, and 7.23 for the b*.

Preparation of carboxymethyl cellulose nanofibers and their application in warp size of textile

How to develop the warp sizing process with energy saving and emission reduction have been a problem for the textile sizing industry. In this work, a series of carboxymethyl cellulose nanofibers (CCNFs) with different degree of substitution (DS) were prepared from bleached eucalyptus kraft pulp, and their applications in warp size of textile were investigated in detail. AFM and TEM analyses confirmed that the prepared CCNFs were of nanoscale fibers. Zeta potential analysis showed that CCNFs aqueous dispersion had good stability. Response surface methodology was applied to optimize the high-count cotton warp sizing formula containing a small amount of CCNFs. It could be found that the optimized sizing formula still had much better sizing performance than that of the original sizing formula even if the sizing percentage and temperature were reduced. The results exhibited that CCNFs with DS of 0.38 had a potential industry application prospect as sizing auxiliary in pure cotton warp sizing, and the new developed sizing formula had the advantages of excellent sizing performance, environmental friendliness, energy saving and emission reduction.

Pre-fibrillation of pulps to manufacture cellulose nanofiber-reinforced high-density polyethylene using the dry pulp direct kneading method

The dry pulp direct kneading method is an industrially viable, low-energy process for manufacturing cellulose nanofiber (CNF)-reinforced polymer composites, where the chemically modified pulps are nanofibrillated and uniformly dispersed in the polymer matrix during melt compounding. In the present study, cellulose fibers of various sizes ranging from surface-fibrillated pulps (20 μm in width) to fine CNFs (20 nm in width) were prepared from softwood bleached kraft pulps using a refiner and a high-pressure homogenizer. These cellulose fibers were modified with alkenyl succinic anhydride and dried. The dried fibers were used as a feed material for melt compounding in the dry pulp direct kneading method to fabricate CNF-reinforced high-density polyethylene (HDPE). When surface-fibrillated pulps were employed as a feed material, the pulps were nanofibrillated and dispersed uniformly in the HDPE matrix during melt compounding. The resulting composites had much better properties—i.e., much higher tensile modulus and strength values, and much lower coefficient of thermal expansion values—than the composites produced using pulps without pre-fibrillation. However, when CNFs were used as a feed material, they were shortened and agglomerated during melt compounding, and the properties of the composites consequently deteriorated. The study concludes that surface-fibrillated pulp, which can be produced cost-effectively using a refiner on an industrial scale, is more suitable as a feed material than CNFs for melt compounding in the dry pulp direct kneading method. This finding enables the elimination of a preliminary step in the preparation of CNFs from pulps, which is a time-consuming and energy-intensive process.Graphical abstract