Modification Of Pulp Research Articles

Effect of Pulp Modification and Pulp Mixing Ratio on Fold Crushing Resistance of High Bulk Paper

The demand of packaging paper has been increasing in order to maintain a sustainable environment through the more reliable recycling of the paper packaging. Since better mechanical properties of packaging paper can expand its range of applications, this study aimed to find a way to improve both fold crushing resistance and bulk properties, which are among the most important properties of packaging paper. The study investigated the effects of raw material conditions, such as the type, mixing ratio, and beating degree of pulp fibers, on the properties of high bulk paper. The results showed that the type of wood chips and pulping methods used had a significant impact on mechanical properties and resistance to cracking. Additionally, adding softwood pulp to appropriately beaten hardwood pulp could form a flexible paper structure while maintaining high bulk, thus improving fold crushing resistance.

Enzymatic pulp modification: an excellent way to expand the raw material base for Lyocell applications?

The potential of enzymatic modification procedures was studied to adjust pulp properties for Lyocell process applications. Cellulases with well-defined activity compositions were identified and tested for pulp treatment. The changes of the pulp properties by such biotechnological modification were investigated especially concerning the resulting average degrees of polymerisation (DP) and the molecular weight distributions (MWD).Several industrial cellulases catalysed endo-splitting on solid cellulose. The selected compositions of the tested enzymes effected the intended decrease of the cellulose DP as suitable adaption of the MWD as well as an improvement of the pulp solubility in NMMO. The DP reduction of tested pulp qualities (paper, viscose and plant pulps) reached 20–35% related to the DP of initial pulp. Depending on the used pulp quality, different changes of the molecular weight distributions with increase or decrease of the polydispersities were detected. Because of improved pulp solubility, spinning dopes with excellent solution qualities could be obtained, even when paper pulps with lower α-cellulose were applied. Exemplary, softwood TCF paper pulp was tested for upscaling in staple fibre. Also filament spinning could be successfully carried out. The prepared fibre samples showed good textile-physical properties. Enzymatic treatment could have a great potential for expansion of raw material base in Lyocell process. It could cause cost savings by applying cheaper cellulose pulps. It also provides options for use of alternative pulps from recycled textile fabrics or annual plants, outside of wood or cotton.

Study on the Surface Modification of Pulp with Cationic Polyelectrolyte for the Manufacture of Cationic Cellulose Nanofibril

In this study, we evaluated the effect of modifying the surface of hardwood bleached kraft pulp (HwBKP) on the zeta potential of CNF. Modification of the surface of HwBKP was conducted using C-PAM and poly-DADMAC before mechanical isolation. After the surface of the pulp had been modified, micro-grinding was carried out to make CNF with surface-modified HwBKP. Then the particle size and the zeta potential of the CNFs were analyzed. The average particle size of the CNFs decreased as the pass number of the micro-grinder increased, regardless of the type of polyelectrolytes used. However, the zeta potential of the CNFs manifested different aspects depending on the type of polyelectrolytes used. CNFs made from HwBKP surface-modified with poly-DADMAC showed a charge reversion, but C-PAM could not modify the zeta potential of the CNFs. This result is thought to be due to the different adsorption mechanism, which depend on the type of polyelectrolytes, on the fiber surface. It may be concluded that polyelectrolytes with relatively low molecular weight and high charge density effectively make cationic CNFs by modifying the surface of pulp.

Paper pulp modification and deinking efficiency of cellulase-xylanase complex from Escherichia coli SD5

Ligno-cellulosic enzymes like cellulase and xylanase have potential for modification of paper pulp characteristics. A low molecular weight cellulase - xylanase complex (14KDa) was co-produced using Escherichia coli SD5. Co-existence of these enzymes was found to be advantageous in paper pulp modification and in deinking applications. The cellulase and xylanase exhibited specific activities of 51.95 and 24.64U/mg protein of respectively. Defibrillations, crack formation and changes in functional groups was evident from the SEM and FT-IR analysis of paper pulp following the enzyme treatment. The enzyme facilitated a better reduction of Kappa number and Hexenuronic acid (Hex A) compared to earlier studies. A Δ brightness of approximately 10% were achieved in case of both cellulase and xylanase for different treatment time. The tear strength of recycled paper was also found to increase after the enzymatic treatment. This is the first report on the application of a un-engineered E. coli isolate co-producing cellulase-xylanase for paper industrial application.

Modification of Different Pulps by Homologous Overexpression Alkali-Tolerant Endoglucanase in Bacillus subtilis Y106

Cellulase (mainly endoglucanase, EG) has been used in pulp modification for improving paper quality through environmentally friendly process. But low activity in alkaline pH and high filter paper activity (FPA) were still obstacles for extending the cellulase application in papermaking industry. In the study, an alkali-tolerant EG gene of Bacillus subtilis Y106 was homologous over-expressed for obtaining suitable enzyme used in pulp modification. The engineering strain could produce the crude enzyme with more alkali-tolerant EG and little PFA. Potential of the crude enzyme in modification of different pulps were investigated. It was found that the enzyme could be used for improving drainage and strength properties of pulps from softwood, hardwood and non-wood materials, especially non-wood pulp such as wheat straw pulp. The underlying mechanisms of pulp modification and different effects on various types of pulps by the EG treatment were also discussed by studying the change in fibers characteristics and fiber bonding.

Utility of co-expressed alkali-tolerant endoglucanase and xylanase in ameliorating wheat straw chemical pulp properties

Because of the inferior properties of wheat straw pulp compared with wood pulp, wheat straw pulp needs to be ameliorated to meet the requirements of high-grade paper production. Enzymatic treatment with cellulase and/or xylanase is recognized as an environmentally friendly and effective method for pulp modification; however, an improper enzyme system and low enzyme activity in alkaline pH are still the main obstacles to the industrial application of the enzymes. In this study, we co-expressed alkali-tolerant endoglucanase (EG) and xylanase in Bacillus subtilis Y106-WT and successfully produced alkali-tolerant enzymes that simultaneously contained high EG and xylanase activity, but little FPA and cellobiohydrolase (CBH) activity, i.e., the activities of EG, xylanase, FPA and CBH of the crude enzyme from the fermentation liquor were 8.20, 60.40, 0.12 and 0.02 IU/ml, respectively, after 64 h of fermentation. Compared to the control, the pulp brightness, breaking length, burst index and tear index of wheat straw chemical pulp increased by 2.0% ISO, 8.7%, 16.6% and 9.3%, respectively, and the beating degree decreased by 15% after treatment using the recombinant enzyme with 0.20 IU/ml EG and 1.5 IU/ml xylanase. The synergistic effect between endoglucanase and xylanase occurred during the enzymatic treatment. The possible mechanism of pulp modification was also discussed.

Photochromic paper from wood pulp modification via layer-by-layer assembly of pulp fiber/chitosan/spiropyran

Cellulosic fiber introducing with photochromic properties can be used in many fields such as security packaging, printing paper, and rewritable paper. To introduce photochromic property to individual fiber, a polyelectrolyte composite layer composed of cationic chitosan (CS) and anionic carboxyl–containing spiropyran (SPCOOH) on pulp fibers was designed using layer-by-layer assembly technique. Scanning electron microscope observation showed that the SPCOOH was successfully absorbed onto the surface of fiber. The photochromic characteristic of LbL–treated fiber could be triggered by UV–vis absorption spectrum and the LbL–treated fibers had a good compatibility with pulp fibers. This study gives a highly effective method to impart the photochromic characteristic to paper.

Research on Biological Modification of Pulp to Improve the Strength of Paper

Based on the domestic OCC pulp as raw material, it was found that the optimum conditions for laccase treatment were: the concentration of laccase 16U/g dry pulp, the pulp consistency 5%, temperature 50 °C, pH=5.0 and reaction time 90min. OCC treated with laccase alone can improve paper strength properties. The dry tensile index and wet tensile index of the control sample were 21.80 Nm/g and 0.22 Nm/g, respectively. The dry tensile index and wet tensile index after OCC treated with laccase alone were 23.36 Nm/g and 0.28 Nm /g. Comparing to the control pulp, the dry tensile index and wet tensile index of OCC treated with laccase were increased by 6.88% and 27.3%, respectively. At the same time, the laccase system can obviously improve the strength of the pulp properties with adding the mediator, especially using histidine, the dry and wet strength of paper was largely improved.

Research on Biological and Mechanical Modification of Pulp to Improve the Strength of Paper

By the preceding experiments, we concluded that the optimum conditions for laccase treatment were: the concentration of laccase 16U/g dry pulp, the pulp consistency 5%, temperature 50 °C, pH=5.0 and reaction time 90min. We studied the change of water retention value and carboxyl content changes under the best conditions. As well as we studied the effect of pulp strength properties by biological treatment combined with mechanical treatment. Moreover, environmental scanning microscope images showed that more collapse and more fibrillation were observed on the beating combined with laccasehistidine-treated fiber surface than the control samples, which led to form better bonding between fibers in handsheets resulting in the increase of the paper strength of beating combined with laccasehistidine-treated OCC pulp.

Direct grafting modification of pulp in ionic liquids and self-assembly behavior of the graft copolymers

In this paper, a novel biodegradable biomass-based amphiphile was prepared by direct grafting copolymerization of dissolved pulp with hydrophobic poly (l-lactide) in ionic liquids BmimCl. The molecular structures of the obtained copolymers were confirmed with 1H-NMR, 13C-NMR and 2D HSQC NMR, and their physical properties were studied by TGA and XRD analysis. The self-assembly behaviors of these amphiphilies in aqueous solution was characterized by fluorescence spectrum and their critical micelle concentrations (CMC) were determined to be in the range of 0.326–0.062 mg/mL. TEM observations and DLS analysis revealed that the pulp-derived micelles had spherical and uniform morphology and small diameters (25–125 nm). It was also found that the surface tension of these copolymers solution firstly decreased dramatically with increasing concentration and then approached to a plateau value when the concentration was above their CMC value. MTT assay showed that the pulp-derived amphiphilic micelles exhibited good biocompatibility, which informed that these micelles could be expected to be used in biological regions, especially for the hydrophobic drug delivery system.

Reactivity of dissolving pulps modified by TEMPO-mediated oxidation

The reactivity of dissolving pulps towards derivatization or dissolution is a crucial quality parameter and is mainly determined by the accessibility of the hydroxyl groups. When dissolving pulps are produced from paper-grade pulps by cold caustic extraction (CCE), their reactivity is often inferior as compared to commercial prehydrolysis kraft dissolving pulps. It was hypothesized that pulp reactivity can be enhanced by the introduction of small amounts of substituents to facilitate interchain accessibility. In this study, CCE-treated Eucalyptus globulus kraft paper pulp was subjected to TEMPO-mediated oxidation to initiate partial oxidation of the C6-hydroxyl groups to carboxyl groups. The effect of this pulp modification on the reactivity towards xanthation and the subsequent dissolution in diluted aqueous alkali solution (viscose process) as well as the dissolution in complexing and non-complexing solvents, respectively, was thoroughly examined. The results revealed that the oxidized pulps rich in C6-carboxylate groups impeded the xanthation reaction obviously because of the reduced availability of hydroxyl groups. When N-methylmorpholine-N-oxide monohydrate was used as a direct solvent, a very high content of C6-carboxylate groups was found to reduce the solubility of the pulp fibers as less hydrogen bonds can be formed with NMMO·H2O. In the case of dissolution in the complexing solvent cupriethylenediamine, the dissolution mechanism of cellulose was not deteriorated by the high content of C6-carboxylate groups. Instead, the oxidation procedure increased the hydrophilic character and the swelling capacity of the outer cell wall layers allowed homogeneous dissolution.

Production of Multi-Fiber Modifying Enzyme fromMamillisphaeriasp. for Refining of Recycled Paper Pulp

Enzymatic modification of pulp is receiving increasing interest for energy reduction at the refining step of the paper-making process. In this study, the production of a multi-fiber modifying enzyme from Mamillisphaeria sp. BCC8893 was optimized in submerged fermentation using a response-surface methodology. Maximal production was obtained in a complex medium comprising wheat bran, soybean, and rice bran supplemented with yeast extract at pH 6.0 and a harvest time of 7 d, resulting in 9.2 IU/mL of carboxymethyl cellulase (CMCase), 14.9 IU/mL of filter paper activity (FPase), and 242.7 IU/mL of xylanase. Treatment of old corrugated container pulp at 0.2-0.3 IU of CMCase/g of pulp led to reductions in refining energy of 8.5-14.8%. The major physical properties were retained, including tensile and compression strength. Proteomic analysis showed that the enzyme was a complex composite of endo-glucanases, cellobiohydrolases, beta-1,4-xylanases, and beta-glucanases belonging to various glycosyl hydrolase families, suggestive of cooperative enzyme action in fiber modification, providing the basis for refining efficiency.

Study on Graft Modification of Waste Newspaper Pulp Fiber

It is study that graft modification of waste newspaper pulp fiber. Grafting rate of waste newsprint pulp increases with increasing initiator dosage, DADMAC dosage, reaction temperature and pulp consistency. When those conditions reach a certain value, grafting rate will lower, but the reducing speed is different. The optimal conditions of waste newsprint pulp modification is the initiator dosage is 8%, mole rate of cationic monomer in total monomers is 60%, reaction temperature is 50°C and reaction time is 2h. Grafting rate of waste newsprint pulp is 15.89% under these conditions.

Application of Advanced Wet-End System Using Carboxymethyl Cellulose to Mixed Pulp Slurries for Wood-Containing Paper Production

A pulp modification technique using carboxymethyl cellulose (CMC) at the wet end was applied to mixed pulp slurries containing softwood bleached kraft pulp (SBKP), deinked pulp (DIP), and hydrogen peroxide-bleached thermomechanical pulp (TMP). Introduction of anionic sites by adsorption of the added CMC molecules on the fibers was confirmed by an increase in negative charge of the mixed pulp fibers. Sizing degree of the handsheets prepared with 2% aluminum sulfate and 0.2% rosin dispersion size was clearly improved by 0.1% CMC addition. On the other hand, we observed no significant differences in rosin size content between the handsheets prepared with and without CMC. These results indicate that some mechanisms other than enhancement of rosin size retention may have brought about the clear improvement of sizing performance by the CMC addition. Changes in distribution of rosin size components or some structural changes of rosin size components in the handsheets by the CMC addition may be candidates for sizing development. The CMC addition technique at the wet end is, therefore, also applicable to mixed pulps containing DIP and TMP.

Carboxymethyl Cellulose Treatment As a Method to Inhibit Vessel Picking Tendency in Printing of Eucalyptus Pulp Sheets

This article presents an industrially feasible method to effectively reduce vessel picking tendency by a simple chemical modification of pulp. ECF-bleached eucalyptus kraft pulp was treated with carboxymethyl cellulose (CMC) under specified conditions. The aim was to study the effects on vessel element structure and vessel picking tendency of the laboratory sheets prepared. In addition to the improved strength properties of the sheets, a significant decrease in vessel picking tendency was noted in the laboratory printing test. Whereas refining improved mainly the bonding ability of fibers, CMC treatment effectively enhanced the bonding of vessels as well. Moreover, filmlike structures were formed in the fibrillated areas of the CMC-treated handsheets, and they were concluded to reinforce bonding within the sheet. Also, fragmentation of vessel elements through CMC modification was found to be important and to result in a decreasing picking tendency.

Fourier transform Raman difference spectroscopy for detection of lignin oxidation products in thermomechanical pulp.

Spruce thermomechanical pulp (TMP) was oxidized by the 2,2'azinobis-3-ethylbenzthiazoline-6-sulfonate cation radical (ABTS*+) in the presence and absence of oxygen. The pulp modification was monitored by Fourier transform (FT) Raman difference spectroscopy and other nondestructive spectroscopic methods. The ABTS*+ oxidative system resulted in modifications very similar to the laccase-ABTS-oxygen system, except for the FT-Raman results, which showed a difference in mechanisms attributed to a difference in produced Raman bands. Oxygen resulted in no oxygen-derived products, but only enhanced the production of a specific Raman band of several oxidation-produced bands. Detailed information on lignin reactions can be obtained from FT-Raman signals.

An Infrared Spectroscopic Study of Chemically Modified Chemithermomechanical Pulp

Abstract FT-IR spectroscopy was used to characterize chemically modified wood pulp and to judge the efficiency of different pulp modification processes. Treatment of wood pulp with aliphatic anhydrides was shown to be more effective in a polar solvent such as DMF compared to a non-polar one typified by xylene. The esterification of hydroxyl group associated with the cellulosic material was indicated by the characteristic absorption bands of the resulting cellulosic esters; the degree of hydroxyl conversion was determined by the ratio of peak intensity of hydroxyl and carbonyl stretching vibrations. The so-called “Infrared Acetyl Index” was shown to give a linear correlation with the gravimetrically determined anhydride uptake. Isocyanate modification of wood pulp yielded more complex infrared spectra, because of various secondary reactions of the reactive isocyanate component. Various aromatic isocyanates, used for chemical treatment of the wood pulp, led mainly to urethane formation, as evidenced by the ...

Characterization of chemically modified chemithermomechanical pulp by thermal analysis: Part 2. Treatment with isocyanates

Chemithermomechanical pulp (CTMP) was chemically treated with different mono-, di., and polyisocyanates in dimethylformamide as solvent without any catalyst. Gravimetrical and thermoanalytical methods (differential scanning calorimetry and thermo- gravimetry) were used to determine hydrophilicity and thermal stability of the modified CTMP. Aliphatic isocyanates, such as n-butylisocyanate and hexamethylenediisocyanate, showed a low potential of reaction with CTMP, compared to aromatic isocyanates with equal functionality like phenylisocyanate and diphenylmethane diisocyanate. The use of diphenylmethane diisocyanate and its oligomeric modification poly(methylene(polyphenyl-isocyanate)) as coupling agent did yield an increased thermal stability of the modified pulp compared to untreated pulp. CTMP treated with either one of these two components exhibited identical thermoanalytical behavior. Treatment with the aromatic diisocyanate MDI, however, resulted in an increased reduction of water uptake. FT-IR studies of the isocyanate-modified pulps showed urethane formation as being the main component of these chemical pulp modification processes. The use of phenylisocyanate at high concentration for pulp modification did alter markedly the differential scanning calorimetrical and thermogravimetrical pattern of the CTMP compared to the same treatment with low concentration of phenylisocyanate. The presence of an intense endothermic peak in DSC experiments indicates that in addition to the urethane formation, at least one more reaction component is formed. This might be due either to a secondary reaction between isocyanate and humidity which yields urea or to an isocyanate trimerization product, an isocyanurate. The presence of this secondary reaction component is linked with a high reduction in water uptake of the modified pulp. Model reactions between CTMP and phenylisocyanate under varied reaction conditions confirmed the adsorption or inclusion of a secondary reaction product.

Review of the effect of grinding media on flotation of sulphide minerals

Over the past thirty years, research has revealed that the type of grinding media can have an important effect on flotation separation through modification of pulp chemistry.This paper reviews the results from some key investigations. It introduces some possible mechanisms and presents the effect of grinding media types on flotation of specific minerals.

Chemical Modification of Pulp and Physically Added Chemicals in Paper Making. Pt. II. Grafting Copolymerization with Hydrophilic and Hydrophobic Monomers and Their Binary Mixtures in Comparison to Physically Added Homopolymers and to Classical Chemical Modification

Article Chemical Modification of Pulp and Physically Added Chemicals in Paper Making. Pt. II. Grafting Copolymerization with Hydrophilic and Hydrophobic Monomers and Their Binary Mixtures in Comparison to Physically Added Homopolymers and to Classical Chemical Modification was published on January 1, 1974 in the journal Holzforschung (volume 28, issue 2).