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1
Pintor-Ibarra, Luis Fernando, José de Jesús Rivera-Prado, Sarai Ramos-Vargas, Teófilo Escoto-García, Nancy Eloisa Rodríguez-Olalde, and José Guadalupe Rutiaga-Quiñones. "Kraft pulping and bleaching of Eichhornia crassipes (Mart.) Solms (water hyacinth)." BioResources 15, no. 4 (October 22, 2020): 9243–64. http://dx.doi.org/10.15376/biores.15.4.9243-9264.
Анотація:
Eichhornia crassipes (water hyacinth) was pulped by means of a kraft pulping process with reagent loads of 10 and 20% on a dry matter basis to determine yield, rejects, kappa number, and ash. Fiber classification, brightness, opacity, and viscosity were measured in the brown pulp. Bleaching was performed by means of an O1O2D1(PO)D2HD3 sequence. Yield, kappa number, pH, ash, brightness, opacity, and viscosity were evaluated in the bleached pulp. Finally, a microanalysis of inorganic elements was carried out in both the bleached and unbleached pulp ash. The highest kraft pulp yield was 26.4%, with a 10% reagent load at 120 °C and 30 minutes cooking. It was determined that E. crassipes cellulosic pulp contains large amounts of fines. Results of the bleaching sequence indicate low brightness (58.0 %) and low viscosity (6.43 cP). The most abundant inorganic elements in the ash of both bleached and unbleached pulp were Ca, Mg, P, and Si. These results suggest that E. crassipes biomass might complement cellulosic fibers in pulping processes of low yield, such as the wood fibers used to produce handmade paper.
2
Dislaire, Claire, Bastien Seantier, Marion Muzy, and Yves Grohens. "Mechanical and Hygroscopic Properties of Molded Pulp Products Using Different Wood-Based Cellulose Fibers." Polymers 13, no. 19 (September 23, 2021): 3225. http://dx.doi.org/10.3390/polym13193225.
Анотація:
With an increasing interest for molded pulp product (MPP) in the industry, it is important to fully understand how the manufacturing process is different from papermaking. One specific way to differentiate the processes is to compare their resulting products. As the paper industry uses several wood fibers with various pulping processes, it is interesting to compare some of these fibers, to further progress our understanding of the MPP process. In this study, six different wood fibers were used (as received) and analyzed to obtain the sample with the lowest moisture uptake and highest tensile properties. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and fiber analysis module (MorFi) observations were performed, as well as moisture uptake measurements after sorption and tensile tests. We observed significant differences between the fibers tested. Kraft fibers (bleached softwood kraft pulp (BSKP), bleached hardwood kraft pulp (BHKP), and unbleached softwood kraft pulp (USKP)) showed smoother surfaces and less non-cellulosic molecules, such as hemicellulose, lignin, and pectin, in the SEM images. Bleached chemi-thermomechanial pulp (BCTMP) and recycled pulps (R-NPM and R-CBB) both showed non-cellulosic molecules and rougher surfaces. These results were confirmed with the FTIR analysis. With kraft fibers, MPP mechanical properties were lower than non-kraft fibers. Resulting moisture uptake is in between the recycled fibers (lowest moisture uptake) and BCTMP (highest moisture uptake). The removal of non-cellulosic molecules reduces the mechanical properties of the resulting MPP. The incorporation of non-wood molecules, as found in recycled fibers, also reduces the mechanical properties, as well as moisture uptake, when compared with BCTMP.
3
Rosenau, Thomas, Antje Potthast, Paul Kosma, Hans U. Suess, and Norbert Nimmerfroh. "Isolation and identification of residual chromophores from aged bleached pulp samples." Holzforschung 61, no. 6 (November 1, 2007): 656–61. http://dx.doi.org/10.1515/hf.2007.108.
Анотація:
Abstract Three bleached and subsequently aged cellulosic pulps have been analysed for their chromophore content according to the chromophore release and identification (CRI) method. Several chromophores have been unambiguously identified, despite their very low content (ppb range). This is the first report on defined chromophoric structures isolated from bleached pulps. It is also the first application of the CRI method to cellulose I substrates, rather than to cellulose II substrates (fibres) and cellulose derivatives as hitherto performed. A common feature of the chromophores is the 2-hydroxy-[1,4]benzoquinone moiety, which is strongly stabilized by resonance or tautomerism. The structure of the chromophores indicates that oxidised carbohydrate structures act as precursor moieties, which condense upon ageing to the chromophore structures identified.
4
BOTARO, VAGNER ROBERTO, KÁTIA MONTEIRO NOVACK, JORGE LUIZ COLODETTE, and LEONARDO SOUZA DE CAUX. "Effect of ultraviolet irradiation on the thermal stability of bleached eucalyptus kraft pulp." February 2012 11, no. 2 (March 1, 2012): 69–74. http://dx.doi.org/10.32964/tj11.2.69.
Анотація:
The changes occurring on cellulosic fibers caused by ultraviolet irradiation at 360 nm for 24 h and 48 h were investigated. A never-dried industrial Eucalyptus urograndis elemental chlorine free–bleached kraft pulp sample (O/OD[EP]DP sequence) was used throughout the work. After irradiation, the cellulosic fibers were analyzed for polymerization degree changes, extractive and pentosan content, ultraviolet and visible spectrometric changes of water leachate from the fibers and thermal analysis (TGA/DTA). The ultraviolet treatment had no effect on the degree of cellulose polymerization. The water extracted from ultraviolet-treated fibers revealed cellulose oxidation, with increasing absorbance signals for carbonyl and carboxyl groups. Those oxidations influenced fiber thermal stability.
5
Hospodarova, Viola, Nadezda Stevulova, Jozef Junak, Anton Geffert, Frantisek Kacik, and Jaroslav Briancin. "Cement Materials Based on Cellulosic Fibers for Plasters." Selected Scientific Papers - Journal of Civil Engineering 12, no. 1 (June 27, 2017): 37–46. http://dx.doi.org/10.1515/sspjce-2017-0004.
Анотація:
Abstract This paper presents physical and mechanical properties of cementitious composites/plasters containing cellulosic fibers in portion 2.0% and 5.0% of filler replacement after 28 days of hardening. Cellulosic fibers (Greencel) originated from bleached wood pulp and unbleached waste paper used in this experimental work were characterized from the point of view cellulose structure. Experimental investigations reveal that adding cellulosic fibers reduces composites density (up to 8.2 %) in comparison with composites without any fibers. Moreover, the presence of wood pulp and recycled fibers in composites cause higher values of water absorbability than sample without fibers. Also, the decrease in compressive strength values for tested fiber cement plasters was observed (14.1 - 18.0 MPa) in comparison to reference sample (26.6 MPa). But the identified compressive strength values are in accordance with European standard (5 MPa) for plasters.
6
Vargas, R., J. R. Sanjuán D., J. A. Silva G., J. Rivera P., F. J. Fuentes T., and H. G. Richter. "Properties of bleached pulp sheets of avocado wood (Persea americana Mill.) pulped by Kraft and Soda processes." Madera y Bosques 12, no. 1 (August 31, 2016): 29–36. http://dx.doi.org/10.21829/myb.2006.1211248.
Анотація:
Chips of avocado wood (Persea americana Mill.) were pulped by means of conventional Soda and Kraft pulping processes. The pulps were bleached with an elemental-chlorine-free sequence OD1-Eop-D2, pre-setting reaction conditions for the first chlorine dioxide stage (D1) . The results show that during the chemical pulping process, avocado wood is easier to cook than other hardwoods such as eucalyptus. The avocado pulp also showed a very good bleachability, reaching brightness levels of up to 92% ISO compared to 84% for eucalyptus after the ECF bleaching sequence. The avocado Kraft pulps required more chemical input in the bleaching sequence than the Soda pulps. On the other hand, the physico-mechanical properties of the pulp were not notably reduced by the bleaching process, the Kraft pulp being stronger than the soda pulp. Strength properties of avocado are similar to those of eucalyptus; therefore this raw material constitutes a worthwhile choice for cellulosic fiber supply.
7
Dalvi, Leandro Coelho, Christiane Laine, Tommi Virtanen, Tiina Liitiä, Tiia-Maria Tenhunen, Hannes Orelma, Tekla Tammelin, and Tarja Tamminen. "Study of xylan and cellulose interactions monitored with solid-state NMR and QCM-D." Holzforschung 74, no. 7 (July 28, 2020): 643–53. http://dx.doi.org/10.1515/hf-2019-0221.
Анотація:
AbstractDevelopment of physical properties of bleached eucalyptus kraft pulp is typically based on the refining process. However, many studies have reported that xylan deposition is a viable alternative. As the mechanisms of xylan and cellulose interactions are not clear, the main goal of this study was to achieve a better understanding of these interactions. Considering that a sample of pulp enriched with xylan is a very complex matrix, a model system was developed. Cellulosic thin films were prepared by spincoating and the Langmuir-Schaefer (LS) method from trimethylsilylcellulose (TMSC). Their interactions with xylan were analyzed using the quartz crystal microbalance with dissipation (QCM-D) monitoring technique. The topological changes on cellulose were studied using atomic force microscopy (AFM). For the 13C solid-state nuclear magnetic resonance (NMR) studies, samples were prepared using commercial microcrystalline cellulose (MCC) and xylan. The xylan was extracted from bleached birch kraft pulp using a cold caustic extraction (CCE) method. The QCM-D monitoring showed deposition only with higher concentrations of xylan solution (1 mg · l−1) for the LS method. The AFM images showed that xylan deposits as agglomerates on the cellulose surface, and the NMR experiments showed that there are interactions for the more ordered region of the cellulose fiber and for the less-ordered region.
8
Palme, Anna, Hans Theliander, and Harald Brelid. "Acid hydrolysis of cellulosic fibres: Comparison of bleached kraft pulp, dissolving pulps and cotton textile cellulose." Carbohydrate Polymers 136 (January 2016): 1281–87. http://dx.doi.org/10.1016/j.carbpol.2015.10.015.
9
Kidalova, Lucia, Nadežda Števulová, and Anton Geffert. "Study of Cement Composites Properties with Filler Based on Wood Pulp." Advanced Materials Research 897 (February 2014): 165–70. http://dx.doi.org/10.4028/www.scientific.net/amr.897.165.
Анотація:
Sustainable building materials are based on the use of renewable materials instead of non-renewable. A large group of renewable raw materials are materials of plant origin containing cellulosic fibres which are used as filler into building material with reinforcement function of composite. This study aimed to establish the mechanical and physical properties of cement composites with organic filler, such as wood pulp. Pulp derived from wood pulping process is very interesting material as reinforcement in cement which contributes to a reduction of pollutants. In this paper, utilization of unbleached and bleached wood pulp in combination with cement matrix with emphasis on the physical and mechanical properties is studied. Varying the producing technology (wood pulp and cement ratio in mixture) it is possible to obtain composites with density from 940 to 1260 kg.m-3 and with compressive strength from 1.02 to 5.44 MPa after 28 days of hardening. The experimental results of mechanical properties indicate that cement composites with using unbleached wood pulp reaches higher values than composites based on bleached wood pulp. The percentage of water uptake increased with increasing the volume ratio of unbleached wood pulp in composite.
10
Pratiwi, Wieke, Andoyo Sugiharto, and Susi Sugesty. "The Effect of Pulping Process Variable and Elemental Chlorine Free Bleaching on the Quality of Oil Palm Trunk Pulp." JURNAL SELULOSA 8, no. 02 (December 31, 2018): 85. http://dx.doi.org/10.25269/jsel.v8i02.218.
Анотація:
Oil Palm Trunk (OPT) is a non-wood cellulosic raw material which is not yet widely utilized in pulping and papermaking. Research on the utilization of abundant Oil Palm Trunk (OPT) from Sabah (Malaysia) and Lebak (West Java Province) for pulp production was carried out using kraft and soda anthraquinone processes with active alkali (AA) of 13-17%. The raw material was chipped and depithed as pretreatment. Bleaching of pulp was carried out using Elemental Chlorine Free (ECF) process. Analysis of raw material covered physical and chemical properties, and fiber morphology. Both OPT fibers were classified into the moderate fiber length (1.05-1.37 mm). Sabah OPT were very bulky with the chips pile density of 102.16 kg/m3 and 62.91 kg/m3 for undepithed and depithed OPT, respectively. The physical properties of OPT pulps were comparable to that of Acacia mangium pulp. With respect to the bleachability and physical properties, pulping of Lebak OPT using kraft or soda-anthraquinone process with AA of 15% were considered as optimum condition. Depithing on Sabah OPT with high pith content could increase physical properties of pulp. ODEoDnD bleaching sequence on pulps from Sabah OPT gave satisfactory results with respect to the physical properties. Since Sabah OPT had a high pith content, the yields of bleached pulp were relatively low (24.67-26.73%). However, the physical properties of the undepithed and depithed Sabah OPT bleached pulp were higher compared to those of the SNI of Leaf Bleached Kraft Pulp (LBKP).Keywords: depithing, Elemental Chlorine Free, bleached pulp, physical properties, LBKP Pengaruh Variabel Proses Pulping dan Pemutihan Elemental Chlorine Free pada Kualitas Pulp Batang Kelapa SawitAbstrakBatang Kelapa Sawit adalah bahan baku selulosa non-kayu yang belum banyak digunakan dalam pembuatan pulp dan kertas. Penelitian tentang pemanfaatan Batang Kelapa Sawit (BKS) dari Sabah (Malaysia) dan Lebak (Provinsi Jawa Barat) yang berlimpah untuk produksi pulp menggunakan proses kraft dan soda antrakuinon dengan alkali aktif (AA) kisaran 13-17% telah dilakukan. Penyerpihan dan proses depithing bahan baku dilakukan sebagai perlakuan awal. Pemutihan pulp dilakukan menggunakan Elemental Chlorine Free (ECF). Analisis bahan baku mencakup sifat fisik dan kimia, serta morfologi serat. Kedua serat BKS dapat diklasifikasikan sebagai serat moderat dengan panjang 1,05-1,37 mm. BKS dari Sabah sangat ruah dengan densitas tumpukan serpih masing-masing 102,16 kg/m3 untuk yang belum di-depithing dan 62,91 kg/m3 untuk yang telah di-depithing. Sifat fisik pulp BKS sebanding dengan pulp dari Acacia mangium. Sehubungan dengan kemampuan pemutihan dan sifat fisik, pembuatan pulp BKS dari Lebak menggunakan proses kraft atau soda-antrakuinon dengan AA 15% adalah kondisi optimal. Depitihing BKS dari Sabah dengan kandungan pith yang tinggi dapat meningkatkan sifat fisik pulp. Pemutihan dengan urutan ODEoDnD untuk pulp BKS dari Sabah memberikan hasil sifat fisik yang memuaskan. BKS dari Sabah memiliki kandungan pith yang tinggi sehingga rendemen pulp yang diputihkan relatif rendah (24,67-26,73%). Namun, sifat-sifat fisik pulp putih BKS dari Sabah yang belum dan telah di-depithing lebih tinggi dibandingkan SNI Pulp Kraft Putih Kayudaun (LBKP).Kata kunci: depithing, Elemental Chlorine Free, pulp putih, sifat fisik, LBKP
11
Morais, Flávia P., Ana M. M. S. Carta, Maria E. Amaral, and Joana M. R. Curto. "Cellulose fiber enzymatic modification to improve the softness, strength, and absorption properties of tissue papers." BioResources 16, no. 1 (December 11, 2020): 846–61. http://dx.doi.org/10.15376/biores.16.1.846-861.
Анотація:
Effects of enzymatic modification were evaluated in bleached Eucalyptus kraft and sulfite cellulosic pulps, separately, to improve key tissue paper properties and design new Eucalyptus fiber applications. Different cellulase dosages (0.01 mg and 0.1 mg of enzyme/g of pulp) and reaction times (30 min and 60 min) were used to modify the fibers and replace the traditional mechanical based refining or beating process. The results showed that for enzymatic modified kraft and sulfite pulps, the softness properties were improved by 1 and 2 units, respectively, for each unit of decreased strength properties. To achieve a balance between the tissue properties, the different fiber pulp furnishes that contained 80% of the enzymatically treated kraft pulp and 20% of the sulfite pulp with and without enzymatic treatment, were studied. Overall, the structures made with these mixtures presented softness properties in the commercial range (57.8 to 74.4), improved absorption properties (107 mm to 120 mm of capillary rise), and good strength properties (13.0 to 17.7 N.m/g). This study was conducted in order to adjust the fiber furnishes according to industrial tissue standards, using one Eucalyptus fiber type providing strength and another providing softness.
12
Števulova, Nadežda, Viola Hospodárova, and Adriana Eštoková. "Study of Thermal Analysis of Selected Cellulose Fibres." GeoScience Engineering 62, no. 3 (December 1, 2016): 18–21. http://dx.doi.org/10.1515/gse-2016-0020.
Анотація:
Abstract This paper provides the investigation of thermal analysis of cellulose fibres which will be used into building materials as a partial filler replacement. Cellulosic fibres come from two various sources: bleached wood pulp and unbleached waste paper whereas these natural fibres have different cellulose contents and another manufacturing process. Natural fibres have been widely used as reinforcing fillers in composite materials in recent years. As a result, they are subjected to thermal degradation during composite processing. It is thus of practical significance to understand and predict the thermal decomposition process of natural fibres and the knowledge will help better design the composite process and estimate the influence on composite properties by the thermal decomposition of natural fibres. The results obtained from the thermal analysis of cellulosic fibres showed differences in their thermal decomposition and also differences in the weight loss due to their chemo-mechanical treatment, the presence of impurities and CaCO3 originating from filler in paper making.
13
Pu, Yunqiao, and Arthur J. Ragauskas. "Structural analysis of acetylated hardwood lignins and their photoyellowing properties." Canadian Journal of Chemistry 83, no. 12 (December 1, 2005): 2132–39. http://dx.doi.org/10.1139/v05-231.
Анотація:
Lignin was isolated from aspen bleached chemithermomechanical pulp by employing a mild acid hydrolysis procedure, and the extracted material was acetylated with acetic anhydride. Nuclear magnetic resonance analyses indicated that the relative ease of acetylating lignin hydroxyl groups was phenolic >> γ-side chain > α-side chain. Non-acetylated and acetylated lignins were impregnated onto cellulosic test sheets, and the photo-behavior of the lignins was examined under irradiation with two light sources, a fluorescent lamp and a black lamp. Optical reflective studies indicated acetylation efficiently inhibited the photodiscoloration of aspen bleached chemithermomechanical pulp lignin under visible and near-UV light irradiation. The photostability of the lignin was correlated to the extent of lignin acetylation. The observed photo-stabilization of acetylated lignin during light irradiation was attributed to the acetylation of phenoxy and aliphatic hydroxyl groups in lignin.Key words: green chemistry, hardwood lignin, acetylation, photo-stabilization, photoyellowing, NMR.
14
Ahrenstedt, Lage, Antti Oksanen, Kristian Salminen, and Harry Brumer. "Paper dry strength improvement by xyloglucan addition: Wet-end application, spray coating and synergism with borate." Holzforschung 62, no. 1 (January 1, 2008): 8–14. http://dx.doi.org/10.1515/hf.2008.002.
Анотація:
Abstract The 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.
15
Azevedo, Catarina A., Sofia M. C. Rebola, Eddy M. Domingues, Filipe M. L. Figueiredo, and Dmitry V. Evtuguin. "Relationship between Surface Properties and Fiber Network Parameters of Eucalyptus Kraft Pulps and Their Absorption Capacity." Surfaces 3, no. 3 (June 30, 2020): 265–81. http://dx.doi.org/10.3390/surfaces3030020.
Анотація:
Water absorption capacity is a key characteristic of cellulosic pulps used for different commodities. This property is influenced by the affinity of the pulp fiber surface with water, chemical composition of the pulp, morphology, and organization of fibers in the network. In this study, surface properties of six industrial Eucalyptus bleached kraft pulps (fluff pulps) dry-defiberized in a Hammermill, which were obtained by wood pulping and pulp bleaching under different production conditions, were studied while employing dynamic water vapor sorption and contact angles measurements. The absorption properties of air-laid pulp pads were analyzed following the absorbency testing procedure and the relationship between these properties and pulp’s chemical composition and fiber network structure were assessed by multivariate analysis. The results showed that the accessibility of the fiber surface is related to the reduction of the contact angles, but, at the same time, to the longer absorption time and less absorption capacity of the fiber network. Therefore, the absorption properties of the pulps are not necessarily directly related to their surface properties. Indeed, absorptivity is related to the surface chemical composition, fiber morphology, and fiber network structure. Thus, surface carboxylic groups promote total water uptake, resulting in better absorption capacity. Greater fiber coarseness and deformations (curl and kink) provide a less wettable surface, but a more porous network with higher specific volume, resulting in more absorbent air-laid formulations.
16
Demuner, Iara Fontes, Jorge Luiz Colodette, Fernando José Borges Gomes, and Rubens Chaves de Oliveira. "Study of LCNF and CNF from pine and eucalyptus pulps." Nordic Pulp & Paper Research Journal 35, no. 4 (November 18, 2020): 670–84. http://dx.doi.org/10.1515/npprj-2019-0075.
Анотація:
AbstractNanocelluloses produced from wood pulp are widely studied for various economic applications. Most studies of cellulose nanofibrils (CNF) use lignin-free fibres obtained from bleached pulps; however, unbleached fibres with residual lignin may also be used to obtain lignocelluloses nanofibrils (LCNF). Research on lignocellulose nanofibrils is a recent subject in the field; thus, the aim of the present study was to determine the ultrastructure of lignocellulose nanofibrils compared to cellulose nanofibrils produced from the same raw material. Understanding of nanoparticle properties is of great relevance for their various applications; therefore, complete characterisation of the chemical, physical, and morphological structures of LCNF and CNF produced from pine and eucalyptus woods was performed. Unbleached cellulosic fibres are a viable alternative for LCNF production, which has properties comparable to that of traditional CNF production that uses lignin-free fibres. LCNF from pine and eucalyptus were obtained with 4.0 % and 1.8 % residual lignin, respectively. The nanofibrils had high thermal stability because LCNF had a higher maximum degradation temperature. Due to the low interaction of lignin with water, LCNF had a lower water retention value than CNF.
17
Kasmani, Jafar Ebrahimpour, Hassan Mohammadpour, and Ahmad Samariha. "Replacement of imported long fiber kraft pulp with lignocellulosic nanofibers and cationic materials in the production of durable paper." BioResources 16, no. 2 (April 1, 2021): 3662–77. http://dx.doi.org/10.15376/biores.16.2.3662-3677.
Анотація:
Usage of cellulosic nanofibers, starch-nanocellulose, and polyacrylamide-nanocellulose hybrid systems were investigated for the replacement of imported long bleached kraft fibers in the production of durable papers. In this study, imported softwood kraft pulp was added to cotton pulp at four levels. Nanofibrillated cellulose (NFC) prepared from chemimechanical pulp was added to cotton pulp at a 5% level with optional 1% cationic starch or 0.1% cationic polyacrylamide. Comparative tests were done without NFC at three levels of either cationic starch or cationic polyacrylamide. For each condition, 80 gm-2 handsheets were made, and the physical, mechanical, and optical properties of the paper were compared. The results showed that increases of NFC yielded higher surface smoothness, tensile strength, resistance to bursting, tearing energy, folding endurance, yellowness, and opacity. It also reduced brightness and porosity whether added singly or in combination with cationic starch or polyacrylamide. Increasing cationic starch also increased surface smoothness, tensile strength, resistance to bursting, and folding endurance, but paper opacity was reduced. The field emission-scanning electron microscopy results showed that increased NFC reduced porosity, the paper surface became smoother, and the pores were relatively filled. Finally, the combined treatment of 5% NFC and 1% cationic starch is introduced as a suitable combination.
18
Frigieri, Tânia Cristina, Gustavo Ventorim, and Jaqueline Silveira Comelato Favaro. "THE EFFECT OF WATER REDUCTION IN KRAFT PULP WASHING IN ECF BLEACHING." Revista Árvore 40, no. 6 (December 2016): 1091–98. http://dx.doi.org/10.1590/0100-67622016000600015.
Анотація:
ABSTRACT The main objective of this work was to study the technical viability of using the cellulose bleaching effluent, at several stages of the process, seeking fresh water reduction in pulp washing, and evaluating its effect on pulp quality. Eucalyptus spp. industrial cellulosic pulp with oxygen was used in this experiment. The same bleaching sequence D(E+P)DP was performed ten times, under the same conditions (temperature, consistency and time). Counter current washing was used in the bleaching stages, and each sequence was carried out with different washing factors: 9, 6, 3, 0 m3 of distilled water/ton of pulp, trying to reach brightness of 92 ± 0,5% ISO. The ten sequences sought to achieve the stability of the effluent organic load, measured by the chemical oxygen demand (COD). Then, the COD results were compared to the brightness ones from the bleached pulp. The evaluated results from the ten sequences and four different washings showed an increasing in COD due to the organic load accumulation, resulting from the reuse of effluent from previous sequences. This COD increasing provided the lower brightness results during the cycles, besides the water reduction, evidencing the necessity of washing between bleaching stages. In this study, the obtained result for the pulp washing up to 3m3/t was tolerable and even recommended. On the other hand, the pulp without any washing (0m3/t), due to the lack of enough brightness, it is commercially unviable.
19
Agnes, Erick Afonso, Tânia Vieira De Mello, Éverton Hillig, and Ricardo Yoshimitsu Miyahara. "WOOD PULP FOR POLYMER COMPOSITES PRODUCTION." FLORESTA 51, no. 1 (December 29, 2020): 044. http://dx.doi.org/10.5380/rf.v51i1.67291.
Анотація:
The use of cellulosic fibers in composites is advantageous compared to inorganic materials, because they present lower density, abrasiveness and cost, besides the renewable origin. This study aimed to evaluate the influence of wood pulp obtained by the chemical (bleached and unbleached) and mechanical process, and wood-flour of Pinus taeda as reinforcement in low density polyethylene (LDPE) matrix. The composites were extruded and the specimens molded by compression. The samples were characterized by thermal analysis, density, mechanical properties and scanning electron microscopy (SEM). The incorporation of the wood pulps and the wood flour in the matrix improved the composites mechanical properties and reduced the rate of material degradation. All fibers types acted as nucleating agents because the composites had better mechanical properties than pure LDPE. There was influence of the studied parameters on tensile and flexural strength and the interactions were significant. In general, the highest values of strength and stiffness were obtained with the use of thermo-mechanical process pulp as reinforcement and the lowest values with the use of unbleached chemical process pulp. micrographs analysis showed that the coupling agent was effective for compatibilizing the wood fibers with the LDPE in the composites. It was possible to produce composite materials with good physical and mechanical properties and improved thermal stability by experimental model.
20
Lohtander, Tia, Reima Herrala, Päivi Laaksonen, Sami Franssila, and Monika Österberg. "Lightweight lignocellulosic foams for thermal insulation." Cellulose 29, no. 3 (January 6, 2022): 1855–71. http://dx.doi.org/10.1007/s10570-021-04385-6.
Анотація:
AbstractFoams are mainly composed of dispersed gas trapped in a liquid or solid phase making them lightweight and thermally insulating materials. Additionally, they are applicable for large surfaces, which makes them attractive for thermal insulation. State-of-the-art thermally insulating foams are made of synthetic polymeric materials such as polystyrene. This work focuses on generating foam from surfactants and renewable lignocellulosic materials for thermally insulating stealth material. The effect of two surfactants (sodium dodecyl sulphate (SDS) and polysorbate (T80)), two cellulosic materials (bleached pulp and nanocellulose), and lignin on the foaming and stability of foam was investigated using experimental design and response surface methodology. The volume-optimized foams determined using experimental design were further studied with optical microscopy and infrared imaging. The results of experimental design, bubble structure of foams, and observations of their thermal conductivity showed that bleached pulp foam made using SDS as surfactant produced the highest foam volume, best stability, and good thermal insulation. Lignin did not improve the foaming or thermal insulation properties of the foam, but it was found to improve the structural stability of foam and brought natural brown color to the foam. Both wet and dry lignocellulosic foams provided thermal insulation comparable to dry polystyrene foam. Graphical abstract
21
Števulová, Nadežda, Viola Hospodarova, Vojtěch Václavík, and Tomáš Dvorský. "Physico-Mechanical Properties of Cellulose Fiber-Cement Mortars." Key Engineering Materials 838 (April 2020): 31–38. http://dx.doi.org/10.4028/www.scientific.net/kem.838.31.
Анотація:
This paper is aimed to investigate the total sand filler replacement by two types of cellulosic fibers (bleached wood pulp - WP and recycled fibers from waste paper - RF) in cement-based mortars. Two different types of cement mortar, one with addition of finely ground limestone and other with powdered granulated slag, were mixed with fibers. The changes in consistency of fresh fiber cement mortars and development of compressive and flexural strength of mortars in dependence on hardening time up to 90 days was studied. The development of compressive and flexural strength with increasing hardening time of cellulose fiber mortars and two binders with different properties confirmed that binder mixtures containing finely ground slag and recycled cellulose fibers achieved higher values of these strength parameters. Also adhesion testing of fiber cement mortars on two substrates (ceramic fitting and aerated concrete block) after 28 days of their application showed better adhesion of cement mortars with finely ground granulated slag on the ceramic fitting surface compared to the mortars containing finely ground limestone. However, any cracks have occurred on both substrates during the maturing of mortars with slag. Based on the above facts, it can be concluded that suitable plaster mixtures for their use in the interior appear the cement recipes with both cellulose fibers (wood pulp and fibers from recycled waste paper) and with finely ground limestone.
22
Xiao, Yuehua, and Gyosuke Meshitsuka. "Development of high-retention water absorbent from cellulosic materials: water absorbent from bleached kraft pulp." Journal of Wood Science 47, no. 5 (October 2001): 394–99. http://dx.doi.org/10.1007/bf00766792.
23
Stone, Derek W., Sarath M. Vega Gutierrez, Zielle M. Walsh, and Seri C. Robinson. "Preliminary Exploration of the Red Pigment from Scytalidium cuboideum as a Cellulosic Pulp Colorant." Challenges 13, no. 1 (April 7, 2022): 15. http://dx.doi.org/10.3390/challe13010015.
Анотація:
Pollution from the international dye industry continues to be a global problem. Biotechnology offers new options, including a closer look at select wood decay fungi to replace inorganic dyes. The pigments produced by a small group of soft rotting fungi are generally naphthoquinonic and remarkably stable. From this group, the dramada crystals, produced by Scytalidium cuboideum, are of particular interest. To test the application of this pigment as a natural colorant of cellulosic pulps, four different bleached pulps were selected (one hardwood, three softwood), in three different mediums (acetone, ethanol, and DI water). The pigment generated a significant change of color, but there was no significant difference in color intensity based on the solvent carrier. These preliminary results are promising as they open the door for further exploration of applications of fungal pigments in the paper industry. Once these pigments can be reliably grown, they will offer a sustainable organic alternative to polluting inorganic dyestuffs and help reduce the toxic effluent released into the soil and waterways.
24
Sanglard, Marion, Christine Chirat, Bevan Jarman, and Dominique Lachenal. "Biorefinery in a pulp mill: simultaneous production of cellulosic fibers from Eucalyptus globulus by soda-anthraquinone cooking and surface-active agents." Holzforschung 67, no. 5 (July 1, 2013): 481–88. http://dx.doi.org/10.1515/hf-2012-0178.
Анотація:
Abstract Industrial Eucalyptus globulus wood chips were submitted to different autohydrolysis conditions followed by kraft cooking and soda-anthraquinone cooking. The autohydrolyzed wood chips were much easier to delignify than the control wood chips. Soda-anthraquinone cooking could be performed at a cooking temperature that was 20°C lower than that for the kraft cooking on control wood chips. Furthermore, the active alkali could be reduced. The resulting unbleached pulps reacted as well to oxygen delignification as the control pulps and could be further bleached to 90% ISO brightness with a D(EP)D sequence. The autohydrolysis liquors were investigated for their suitability as a source for the synthesis of alkylpolyxylosides (APX). These surface-active agents are synthesized through the reaction between the saccharides of the autohydrolysates and a fatty alcohol, with the former being the hydrophilic and the latter being the hydrophobic part of the molecule. The impact of the substances detected in autohydrolysates on the APX synthesis was studied. It was demonstrated that lignin dissolved during autohydrolysis should at least partially be removed before the production of APX.
25
Korpela, Antti, Atsushi Tanaka, and Alistair W. T. King. "A comparative study of the effects of chemical crosslinking agents on NBSK handsheet properties." BioResources 18, no. 1 (December 7, 2022): 937–48. http://dx.doi.org/10.15376/biores.18.1.937-948.
Анотація:
Chemical crosslinking is an established method for improving the wet performance of paper. In the chemical crosslinking process, covalent bonds are formed between cellulosic surfaces. The formed intra- and inter-fiber bonds increase the paper’s wet strength and reduce its water absorptivity. The majority of published studies concern crosslinking treatments with glyoxal, citric acid (CA), or with 1,2,3,4-butanetetra-carboxylic acid (BTCA). The most severe disadvantage of the crosslinking treatments with glyoxal, CA, and BTCA is that the formed crosslinks make the fibers and the paper more brittle. This downside effect has largely impeded the utilization of crosslinking in paper and paperboard making. In the present study, handsheets made from Nordic bleached softwood kraft pulp (NBSK) were crosslinked with methylated 1,3-dimethylol-4,5-dihydroxyethylene urea (mDMDHEU), which is commonly used in cotton fabric finishing. Similar to using glyoxal and citric acid, crosslinking with mDMDHEU notably increased the handsheet wet strength and decreased the water absorption. Compared to the use of glyoxal or CA, the crosslinking with mDMDHEU did not make the handsheets that brittle. These results suggest that mDMDHEU could be a more viable crosslinking agent for improving the wet performance of paper products.
26
Potthast, Antje, Sonja Schiehser, Thomas Rosenau, Herbert Sixta, and Paul Kosma. "Effect of UV radiation on the carbonyl distribution in different pulps." Holzforschung 58, no. 6 (October 1, 2004): 597–602. http://dx.doi.org/10.1515/hf.2004.113.
Анотація:
Abstract The effect of UV irradiation on unbleached and TCF-bleached dissolving pulp samples of different provenience, a beech sulphite and an eucalyptus prehydrolysis kraft pulp, has been analyzed according to the CCOA method, evaluating the changes in the molecular weight distribution, the total number of carbonyl groups and the carbonyl group profiles of each pulp. In the case of TCF bleached material, slightly more carbonyl groups were introduced into the kraft pulp as compared to the sulfite pulp. Cellulose degradation was relatively low in both pulps. In the case of unbleached sulfite pulps, the residual lignin had only a minor effect on the molecular weight distribution and the oxidation state of the cellulose, whereas for eucalyptus kraft pulp a pronounced introduction of carbonyl groups accompanied by severe degradation of cellulose was observed. The presence of hemicelluloses governed the photochemical behavior and the carbonyl profiles of the low molecular weight region of the cellulose.
27
Hassan, Mohammad L., Wafaa S. Abou-Elseoud, Amal H. Abdel Kader, and Enas A. Hassan. "Rice straw paper sheets reinforced with bleached or unbleached nanofibers." Nordic Pulp & Paper Research Journal 36, no. 1 (February 18, 2021): 139–48. http://dx.doi.org/10.1515/npprj-2020-0073.
Анотація:
Abstract Cellulose nanofibers isolated from unbleached pulp are characterized by different surface properties due to presence of lignin at their surface, in addition to lower cost than isolated from bleached pulp. In the current work, the effect of cellulose nanofibers isolated from unbleached neutral sulfite and bleached soda rice straw pulps (so called UBCNF and BCNF) on improving paper sheet properties of unbleached and bleached rice straw pulp (so called UBP and BP) was studied. The effect on mechanical properties (tensile strength, burst strength, and tearing resistance) and physical properties (porosity and water vapor permeability) was studied. Scanning electron microscopy (SEM) was used to assist in explaining the obtained results. The result showed that using BCNF and BP resulted in better improvement in mechanical properties and also more effective in reducing porosity of paper sheets than in case of using UBCNF and UBP. These results indicated stronger bonding between nanofibers and pulps’ fibers in case of using BCNF and BP (surfaces rich in cellulose hydroxyl groups) than in case of UBCNF and UBP (surfaces rich in lignin). Water vapor permeability of paper sheets made from unbleached or bleached pulps did not significantly affect by the addition the nanofibers.
28
Chen, Zhiwen, Thomas Q. Hu, Ho Fan Jang, and Edward Grant. "Multivariate Analysis of Hemicelluloses in Bleached Kraft Pulp Using Infrared Spectroscopy." Applied Spectroscopy 70, no. 12 (October 28, 2016): 1981–93. http://dx.doi.org/10.1177/0003702816675363.
Анотація:
The hemicellulose composition of a pulp significantly affects its chemical and physical properties and thus represents an important process control variable. However, complicated steps of sample preparation make standard methods for the carbohydrate analysis of pulp samples, such as high performance liquid chromatography (HPLC), expensive and time-consuming. In contrast, pulp analysis by attenuated total internal reflection Fourier transform infrared spectroscopy (ATR FT-IR) requires little sample preparation. Here we show that ATR FT-IR with discrete wavelet transform (DWT) and standard normal variate (SNV) spectral preprocessing offers a convenient means for the qualitative and quantitative analysis of hemicelluloses in bleached kraft pulp and alkaline treated kraft pulp. The pulp samples investigated include bleached softwood kraft pulps, bleached hardwood kraft pulps, and their mixtures, as obtained from Canadian industry mills or blended in a lab, and bleached kraft pulp samples treated with 0–6% NaOH solutions. In the principal component analysis (PCA) of these spectra, we find the potential both to differentiate all pulps on the basis of hemicellulose compositions and to distinguish bleached hardwood pulps by species. Partial least squares (PLS) multivariate analysis gives a 0.442 wt% root mean square errors of prediction (RMSEP) for the prediction of xylan content and 0.233 wt% RMSEP for the prediction of mannan content. These data all support the idea that ATR FT-IR has a great potential to rapidly and accurately predict the content of xylan and mannan for bleached kraft pulps (softwood, hardwood, and their mixtures) in industry. However, the prediction of xylan and mannan concentrations presented a difficulty for pulp samples with modified cellulose crystalline structure.
29
Borrega, Marc, and Hannes Orelma. "Cellulose Nanofibril (CNF) Films and Xylan from Hot Water Extracted Birch Kraft Pulps." Applied Sciences 9, no. 16 (August 20, 2019): 3436. http://dx.doi.org/10.3390/app9163436.
Анотація:
The effects of xylan extraction from birch kraft pulp on the manufacture and properties of cellulose nanofibril (CNF) films were here investigated. Hot water extractions of bleached and unbleached kraft pulps were performed in a flow-through system to remove and recover the xylan. After the extraction, the pulps were oxidized with 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) and fibrillated in a high-pressure microfluidizer. Compared to CNF from bleached kraft pulp, the CNF dispersions obtained from water-extracted pulps were less viscous and generally contained a higher amount of microfiber fragments, although smaller in size. In all cases, however, smooth and highly transparent films were produced from the CNF dispersions after the addition of sorbitol as plasticizer. The CNF films made from water-extracted pulps showed a lower tensile strength and ductility, probably due to their lower xylan content, but the stiffness was only reduced by the presence of lignin. Interestingly, the CNF films from water-extracted bleached pulps were less hydrophilic, and their water vapour permeability was reduced up to 25%. Therefore, hot water extraction of bleached birch kraft pulp could be used to produce CNF films with improved barrier properties for food packaging, while obtaining a high-purity xylan stream for other high-value applications.
30
Uraki, Yasumitsu, and Yoshihiro Sano. "Polyhydric Alcohol Pulping at Atmospheric Pressure: An Effective Method for Organosolv Pulping of Softwoods." Holzforschung 53, no. 4 (July 1, 1999): 411–15. http://dx.doi.org/10.1515/hf.1999.068.
Анотація:
Summary Polyhydric alcohol pulping was developed to separate components of low-quality softwoods that are produced by thinning and improvement cutting as well as to establish a self-supporting pulping system. Propylene glycol (PG) was superior to ethylene glycol (EG) as solvent for polyhydric alcohol pulping at atmospheric pressure. PG pulping of fir, larch and cedar, with sulfuric acid as a catalyst, gave satisfactory pulps with few rejects and a very low level of residual lignin as compared with EG pulping. The PG pulps were readily bleached to approximately Kappa number 1 and 80% brightness by one treatment with sodium chlorite. The yield of bleached pulp from fir was 44.7% based on chips. The bleached pulps had very high α-cellulose content and crystallinity, and their mechanical properties were similar to those of kraft pulp. Therefore, polyhydric alcohol pulping appears to be promising for pulping of softwoods by an organosolv method.
31
Nocanda, Xolani, Per Tomas Larsson, Andrew Spark, Tamara Bush, Ann Olsson, Mzekelo Madikane, Ajay Bissessur, and Tommy Iversen. "Cross polarisation/magic angle spinning 13C-NMR spectroscopic studies of cellulose structural changes in hardwood dissolving pulp process." Holzforschung 61, no. 6 (November 1, 2007): 675–79. http://dx.doi.org/10.1515/hf.2007.095.
Анотація:
Abstract Cross polarisation/magic angle spinning 13C NMR spectroscopy has been used to study structural changes in cellulose induced by the dissolving pulp process. The cellulose structure in several dissolving pulps was investigated for commercial and laboratory cooked Eucalyptus 92α and 96α. The average lateral dimension, or average thickness, of the cellulose fibril aggregates is related to the amount of surface area exposed and could be one controlling factor for the chemical reactivity of commercial dissolving pulps during modification reactions. The thickness of the cellulose fibril aggregates governs the amount of surface area present in the fibre wall, and cellulose surface material constitutes the part of the cellulose that is directly accessible to reagents. In all sample series investigated, the raw pulp was found to be less aggregated than the corresponding bleached final pulp. Furthermore, an irreversible increase in fibril aggregate width was observed on free drying for both laboratory cooked and commercial pulps. Upon rewetting with water, the freely dried 96α pulp was found to be more aggregated than the freely dried 92α pulp, although sugar analysis showed very similar carbohydrate compositions. As indicated by the molecular mass distribution, the commercial 92α pulp contained larger amounts of degraded cellulose; this may be a plausible explanation for the different behaviour of the 92α and 96α pulps during free drying.
32
Saariaho, A. M., A. S. Jääskelinen, P. Matousek, M. Towrie, A. W. Parker, and T. Vuorinen. "Resonance Raman spectroscopy of highly fluorescing lignin containing chemical pulps: Suppression of fluorescence with an optical Kerr gate." Holzforschung 58, no. 1 (February 5, 2004): 82–90. http://dx.doi.org/10.1515/hf.2004.011.
Анотація:
Abstract Raman spectroscopy using 400 nm excitation was successfully applied to chemical pulp samples and the fluorescence background that usually limits the application of this method to such samples was effectively suppressed. This enabled the detection of much weaker Raman bands from the pulps. The rejection ratio of the fluorescence background to Raman scattering was estimated to be about 250. The resonance Raman spectra of peroxide bleached chemical pulps had chromophoric lignin bands at 1605 and 1655 cm−1, whereas the chlorine dioxide bleached pulps had only the aromatic band at 1605 cm−1. The square root of the aromatic chromophore band relative to cellulose band correlated linearly with the brightness which is in accordance with the Kubelka-Munk theory. This correlation indicated that the resonance enhanced Raman bands were mainly due to chromophoric lignin structures. Chlorine dioxide and peroxide bleached pulps gave different correlations to brightness, which was an indication of different kinds of chromophores in these pulps. The intensity of the aromatic band relative to the cellulose band was about 20 times higher with the ultraviolet (257 nm) than with the visible (400 nm) excitation. This clearly illustrated the importance of working with different excitation wavelengths. On one hand the UV excitation is more sensitive towards aromatic residual lignin in pulp, and on the other hand the visible excitation enables the selective detection of chromophoric lignin structures.
33
Boschetti, Walter Torezani Neto, Ana Márcia Macedo Ladeira Carvalho, Angélica de Cássia Oliveira Carneiro, Graziela Baptista Vidaurre, Fernando José Borges Gomes, and Déborah Nava Soratto. "Effect of Mechanical Treatment of Eucalyptus Pulp on the Production of Nanocrystalline and Microcrystalline Cellulose." Sustainability 13, no. 11 (May 24, 2021): 5888. http://dx.doi.org/10.3390/su13115888.
Анотація:
This study aimed to assess the effect of mechanical pretreatment on bleached eucalyptus kraft pulp fibers and investigate the influence of reaction time and temperature on the properties and yield of nanocrystalline cellulose (NCC) and microcrystalline cellulose (MCC). Two types of pulps were hydrolyzed, pulp 1 (control, whole fibers) and pulp 2 (mechanically pretreated, disintegrated fibers). NCC and MCC particles were obtained by sulfuric acid hydrolysis (60% w/w) of eucalyptus pulps under different conditions of time (30–120 min) and temperature (45–55 °C). Physical treatment of kraft pulp facilitated acid hydrolysis, resulting in higher NCC yields compared with no pretreatment. The morphologic properties and crystallinity index (CI) of NCC and MCC were little affected by pulp pretreatment. NCC particles obtained from pulps 1 and 2 were needle-shaped, with mean diameters of 6 and 4 nm, mean lengths of 154 and 130 nm, and CI of 74.6 and 76.8%, respectively. MCC particles obtained from pulps 1 and 2 were rod-shaped, with mean diameters of 2.4 and 1.4 µm, mean lengths of 37 and 22 µm, and CI of 73.1 and 74.5%, respectively. Pulps 1 and 2 and their respective NCC and MCC derivatives had a cellulose I crystalline structure.
34
LIU, WEN, SHUKE ZHOU, XIAOHUA QI, and JUNWEN PU. "Preparation of acetate-grade dissolving pulp from eucalyptus by processes including alkaline pretreatment and combined post-treatments with xylanase and alkali." September 2013 12, no. 9 (October 1, 2013): 19–24. http://dx.doi.org/10.32964/tj12.9.19.
Анотація:
In this investigation, alkaline pretreatment before kraft pulping and combined post-treatments with xylanase and alkali after bleaching were applied to obtain an acetate-grade dissolving pulp. Bleaching sequences using oxygen or hydrogen peroxide were also studied. The brightness, α-cellulose content, and degree of polymerization (DP) of the bleached pulps from different bleaching sequences were evaluated. Alkaline pretreatment resulted in a higher α-cellulose content in the pulp. When a D1ED2P bleaching sequence was applied, the pulp obtained had an ISO brightness of 87.5%, a DP of 1050, and an α-cellulose content of 92.7%. The requirements for an acetate-grade dissolving pulp can then be met when followed by combined post-treatments with xylanase and alkali under the optimal conditions of 120 IU•g–1 xylanase dosage and 4% sodium hydroxide concentration.
35
Ruffin, Brigitte, та Alain Castellan. "Photoyellowing of peroxide-bleached lignin-rich pulps: a photochemical study on stilbene-hydroquinone chromophores issued from β-5 units of lignin during refining and (or) bleaching". Canadian Journal of Chemistry 78, № 1 (15 січня 2000): 73–83. http://dx.doi.org/10.1139/v99-230.
Анотація:
The contribution of stilbene-parahydroquinone structures, formed from β-5 units during refining and bleaching, in photoreversion of peroxide-bleached high-yield pulps, was studied using 4'-benzyloxy-2,5-dihydroxy-3,3'-dimethoxystilbene (I), as a model compound. The various photoproducts formed during irradiation of I in solution or adsorbed on cellulose paper were identified. Isomerization of the stilbene double bond and oxidation of the hydroquinone into quinone were observed in solution, whereas in the solid state only the formation of the quinone was found to operate. Our attempts to detect and quantify stilbene-hydroquinones forming from β-5 units created on peroxide bleached mechanical pulp were not met with success.Key words: lignin, stilbene, hydroquinone, lignin model compound, pulp, photoyellowing.
36
SHARMA, ARVIND, GUNJAN DHIMAN, PRITI S. LAL, RAVI D. GODIYAL, and BIPIN P. THAPLIYAL. "CHARACTERISATION OF MORINGA OLEIFERA (DRUMSTICK) WOOD FOR PULP AND PAPER MAKING." Cellulose Chemistry and Technology 55, no. 3-4 (April 20, 2021): 255–62. http://dx.doi.org/10.35812/cellulosechemtechnol.2021.55.25.
Анотація:
"Moringa oleifera (drumstick) wood was evaluated in terms of its chemical composition, morphological features, Kraft pulping behavior, ECF bleaching and mechanical strength properties – important parameters for pulp and paper making – in comparison with Acacia mangium. Moringa oleifera was found to have the following composition: holocellulose 65.5%, lignin 20.5%, pentosan 11.6%, -cellulose 40.5% and extractives content of 5.15%, which made it comparable with the Acacia mangium wood sample. The alkali prehydrolysis of Moringa oleifera was carried out using 2% NaOH at 150 °C. The prehydrolysis liquor (PHL) was found to contain 50.9 mg/kg of calcium, 5140 mg/kg of potassium and 312 mg/kg of iron content. The prehydrolysis step was followed by Kraft pulping in order to obtain chemical grade pulp of kappa number 15-16 under optimized conditions. The Moringa oleifera pulp was bleached using the DEpD bleaching sequence to reach 85% brightness (ISO). The bleached pulp had an average fiber length of 1.21 mm, which was higher than that of Acacia mangium – 0.782 mm. The mechanical strength properties of the unbleached and bleached pulps, such as tear, tensile and burst indices, were also determined to show their suitability for pulp and paper production."
37
Jiang, Yu, Yangmei Chen, Qitang Wu, and Zebin Wei. "Fiber structures and properties of eucalyptus kraft pulp via different bleaching methods." Nordic Pulp & Paper Research Journal 34, no. 3 (September 25, 2019): 280–88. http://dx.doi.org/10.1515/npprj-2019-0030.
Анотація:
Abstract The fiber morphology, the content of hydrogen bonds (HBs) of different models, cellulose crystalline structure, water retention value (WRV), and strength properties of eucalyptus pulp bleached by different bleaching methods (hydrogen peroxide bleaching and sodium dithionite bleaching) were investigated. The results of fourier transform infrared spectrometer (FTIR) showed that the content of intramolecular hydrogen bonds (HBintra) increased by 11.6 % and 4.8 % after hydrogen peroxide bleaching and sodium dithionite bleaching, respectively. The energy of the hydrogen bonds was changed after bleaching treatment. The hydrogen bonding distances showed a small change after different bleaching treatment. The results of X-ray diffraction (XRD) demonstrated a decrease in the average width of crystallite size in the (002) lattice plane after different bleaching treatment, which was the same trend with the variability of cellulose crystallinity. Compared with the unbleached pulp, the WRV and strength properties of the bleached pulp increased after each bleaching process. Tear index of handsheets made from the hydrogen peroxide and sodium dithionite bleaching pulps were 46.0 % and 54.8 %, respectively. The sodium dithionite bleaching treatment had more significant effects on fiber swelling capability.
38
GONDO, TOMOHISA, MASASUKE WATANABE, OSAMU KITAO, and AKIRA ISOGAI. "Application of Advanced Wet-End System Using Carboxymethyl Cellulose to Mixed Pulp Slurries for Wood-Containing Paper Production." May 2009 8, no. 5 (June 1, 2009): 32–37. http://dx.doi.org/10.32964/tj8.5.32.
Анотація:
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.
39
FERDOUS, TASLIMA, M. A. QUAIYYUM, KAZI M. YASIN ARAFAT, and M. SARWAR JAHAN. "Characterization of chia plant (Salvia hispanica) for pulping." October 2020 19, no. 10 (November 1, 2020): 511–24. http://dx.doi.org/10.32964/tj19.10.511.
Анотація:
In this paper, chia plant was characterized in terms of chemical, morphological, and anatomical properties. Chia plant was characterized with low α-cellulose (30.5%); moderate lignin (23.2%) with syringyl to guaiacyl ratio of 1.41; and shorter fiber length (0.67 mm) with thinner cell wall (1.91 μm) and good flexibility coefficient (71.44). Anatomical features showed that chia plant consists of vessels, fibers, parenchyma cells, and collenchyma cells. Chia plant pulping was evaluated in soda-anthraquinone (soda-AQ) and formic acid/peroxyformic acid (FA/PFA) processes. Chia plant was difficult to delignify in the alkaline process. The FA/PFA process produced higher pulp yield at the same kappa number than the soda-AQ process. Unbleached soda-AQ chia pulp exhibited good proper-ties in terms of tensile, bursting, and tearing strengths, even at the unrefined stage, due to high drainability of the pulps. Alkaline peroxide bleached FA/PFA pulp exhibited better papermaking properties and 2% higher brightness than the D0(EP)D1 bleached soda-AQ pulp.
40
Gueneau, Basile, Nathalie Marlin, Alain Deronzier, and Dominique Lachenal. "Pulp delignification with oxygen and copper(II)-polyimine complexes." Holzforschung 68, no. 4 (May 1, 2014): 377–84. http://dx.doi.org/10.1515/hf-2013-0134.
Анотація:
Abstract Ten Cu(II)-polyimine complexes were tested as potential catalysts in oxygen delignification of softwood kraft pulps. The ligands were chosen from the terpyridine and the phenanthroline families, including several neocuproines. One diamine-phenanthrene (daphen) was also investigated. The main purpose was to examine whether the presence of methyl or phenyl substituents would direct the oxidation toward lignin. As a catalyst for comparison, unsubstituted 1,10-phenanthroline was selected, which is known to activate both delignification and carbohydrate degradation during oxygen bleaching of kraft pulp. The variation of ligands was aiming at the complex solubility and redox potential of the parameters. The experiments were performed on a mixture of mechanical pulp and fully bleached kraft pulps, a fully bleached pulp alone, and an industrial unbleached pulp. Concerning the oxygen activation in delignification of kraft pulp, 4,7-diphenyl-1,10-phenanthroline was as good as 1,10-phenanthroline, but appeared to be more selective, which resulted in a higher DPv of cellulose after treatment. This was interpreted by the structural similarities between the ligand and the kraft lignin and by a better stability of the intermediate complex with lignin. Two Cu(II)-phenanthroline derivatives complexes (4,7- and 5,6-dimethyl-1,10-phenanthroline) were also identified as effective oxygen activators for the removal of native lignin.
41
Arnoul-Jarriault, Benoît, Raphaël Passas, Dominique Lachenal, and Christine Chirat. "Characterization of dissolving pulp by fibre swelling in dilute cupriethylenediamine (CUEN) solution in a MorFi analyser." Holzforschung 70, no. 7 (July 1, 2016): 611–17. http://dx.doi.org/10.1515/hf-2015-0167.
Анотація:
Abstract The swelling of dissolving pulps has been investigated by a new method based on the MorfiR analyser, which is measuring the width variation of thousands of fibres in a cupriethylenediamine (CUEN) solution in a few minutes. Pulps from various origins were analysed coming from softwood, birch wood, eucalyptus wood, kraft pulps, sulphite pulps and ECF and TCF bleached pulps, which were modified by several treatments including chemical (cold caustic extraction, hypochlorite) or enzymatic (cellulase) methods. The swelling was much affected by the crystalline form of cellulose and the hemicellulose content but did not depend neither on the cellulose DP nor on the fibre structure (hardwood vs. softwood). The dissolving pulp reactivity in the viscose process was also assessed by swelling in dilute solutions of cupriethylenediamine (CUEN) instead of the Fock’s method.
42
Larsson, Per Tomas, and Lennart Salmén. "Influence of cellulose supramolecular structure on strength properties of chemical pulp." Holzforschung 68, no. 8 (December 1, 2014): 861–66. http://dx.doi.org/10.1515/hf-2013-0226.
Анотація:
Abstract The industrially produced chemical pulps have lower strength properties than those obtained under laboratory conditions, and this difference is referred to as the strength delivery (SD) problem. In this study, the hypothesis was put forward that the SD could, at least in part, be accounted for by the supramolecular structure of the cellulose microfibrils of the fiber wall. To test the hypothesis, two bleached softwood kraft pulps (BSKP) were manufactured from the same starting material with different degrees of cellulose aggregation, but the pulps were otherwise as similar as possible in other controllable respects. The chemical and physical properties, including the pulp strength, were tested. A selective increase of the degree of cellulose microfibril aggregation resulted in a pulp with a decreased tear index (TI) at a specified tensile index, and this decrease was similar in magnitude to what is typically encountered in SD. Accordingly, the current experimental study succeeded in mimicking the SD problem. The lateral fibril aggregate dimensions (LFAD) seem to play a pivotal role and it can be safely concluded in general that the supramolecular structure of cellulose in the fibers may be an important factor contributing to the SD problem.
43
Du, Min, Xin Ping Li, and Meng Luo. "Influence of Cellulase to Filtration and Fiber Morphology of Bleached Softwood Pulp." Advanced Materials Research 550-553 (July 2012): 1182–85. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.1182.
Анотація:
Cellulase named as Celluclast 1.5L was used to deal with bleached softwood pulp. By analyzing the changes of fiber polymerization, fiber length and pulp freeness before and after enzymatic treatment, studied the influence of cellulase to filtration and fiber morphology of bleached softwood pulp, and discussed the mode of action of cellulase to bleached softwood pulp. The results show that while the enzyme dosage increasing, the degree of cellulose hydrolysis increases; the pulp polymerization degree decreases; fiber length decreases and the content of fines increase. Pulp filtration first increases and then decreases, but fiber surface does not appear the phenomenon of fibrillating. It indicates that the action of cellulase to fiber is from the inside to outside.
44
Olmstead, Jennifer A., Jian H. Zhu, and Derek G. Gray. "Fluorescence spectroscopy of mechanical pulps III: Effect of chlorite delignification." Canadian Journal of Chemistry 73, no. 11 (November 1, 1995): 1955–59. http://dx.doi.org/10.1139/v95-241.
Анотація:
Many paper and wood samples fluoresce, but the sources of the emission are not well understood. Fluorescence excitation and emission spectra of paper sheets prepared from thermomechanical pulp (TMP) and bleached chemithermomechanical pulp (BCTMP) showed that the emission from the BCTMP was significantly higher than that from the TMP. Removing almost all of the lignin from both pulps by means of an acid chlorite treatment did not reduce the fluorescence significantly. By means of an approximate correction for changes in sheet reflectivity caused by the chlorite treatment, the fluorescence intensity was found to increase with lignin removal. Clearly, fluorescence is not simply related to lignin content. Keywords: wood pulp, lignin, cellulose, fluorescence spectra, acid chlorite delignification.
45
Hassan, Mohammad, Ragab E. Abou Zeid, Wafaa S. Abou-Elseoud, Enas Hassan, Linn Berglund, and Kristiina Oksman. "Effect of Unbleached Rice Straw Cellulose Nanofibers on the Properties of Polysulfone Membranes." Polymers 11, no. 6 (May 29, 2019): 938. http://dx.doi.org/10.3390/polym11060938.
Анотація:
In addition to their lower cost and more environmentally friendly nature, cellulose nanofibers isolated from unbleached pulps offer different surface properties and functionality than those isolated from bleached pulps. At the same time, nanofibers isolated from unbleached pulps keep interesting properties such as hydrophilicity and mechanical strength, close to those isolated from bleached pulps. In the current work, rice straw nanofibers (RSNF) isolated from unbleached neutral sulfite pulp (lignin content 14%) were used with polysulfone (PSF) polymer to make membrane via phase inversion. The effect of RSNF on microstructure, porosity, hydrophilicity, mechanical properties, water flux, and fouling of PSF membranes was studied. In addition, the prepared membranes were tested to remove lime nanoparticles, an example of medium-size nanoparticles. The results showed that using RSNF at loadings from 0.5 to 2 wt.% can significantly increase hydrophilicity, porosity, water flux, and antifouling properties of PSF. RSNF also brought about an increase in rejection of lime nanoparticles (up to 98% rejection) from their aqueous suspension, and at the same time, with increasing flux across the membranes. Tensile strength of the membranes improved by ~29% with addition of RSNF and the maximum improvement was obtained on using 0.5% of RSNF, while Young’s modulus improved by ~40% at the same RSNF loading. As compared to previous published results on using cellulose nanofibers isolated from bleached pulps, the obtained results in the current work showed potential application of nanofibers isolated from unbleached pulps for improving important properties of PSF membranes, such as hydrophilicity, water flux, rejection, and antifouling properties.
46
Sousa, Cátia T., Dmitry V. Evtuguin, and José L. Amaral. "Hardwood kraft pulp structural features affecting refinability." Holzforschung 71, no. 7-8 (July 26, 2017): 619–24. http://dx.doi.org/10.1515/hf-2016-0205.
Анотація:
Abstract Two industrial bleached Eucalyptus globulus kraft pulps (pulps A and B), cooked from the same wood stock with slightly different alkali charges and temperatures, showed different refinability in the laboratory beating of pulp using a PFI mill. The easy to refine pulp (A) and the difficult to refine pulp (B) did not reveal significant differences in their biometric data and general chemical composition, but pulp A showed ca. 5%–10% higher mechanical strength and twice as high refinability compared to pulp B. These differences were ascribed to slightly higher intrinsic viscosity and higher xylan content of pulp A compared to pulp B (1010 vs. 860 cm3 g−1 and 20.1 vs. 17.8%, respectively). The xylan structure and its location in fiber cells were also different, which affected the pulp’s refinability. The presence of high proportion of xylan in the bulk of fibers, rather than in their outer layers, seems to favor the pulp beating. An interpretation was also proposed, according to which the aggregation of cellulose fibrils during cooking, i.e. a partial coalescence of fibril crystallites, may also have a negative effect on pulp refinability.
47
Laine, C., X. Wang, M. Tenkanen, and A. Varhimo. "Changes in the fiber wall during refining of bleached pine kraft pulp." Holzforschung 58, no. 3 (May 12, 2004): 233–40. http://dx.doi.org/10.1515/hf.2004.036.
Анотація:
Abstract The effect of refining on the fiber wall was studied for bleached kraft pulp fractions from pine first thinnings and pine sawmill chips. Hydrocyclone fractionation of both pulps produced fractions enriched in earlywood and latewood fibers. Some external fibrillation but no changes in fiber wall thickness were observed for the thin-walled earlywood fibers during refining. Refining the thick-walled latewood fibers led to extensive external fibrillation and a decrease in fiber wall thickness. The pore structure of the fiber wall opened up during refining for all pulp fractions. Earlywood fibers were more porous than latewood fibers, and fibers from first thinnings more porous than those from sawmill chips. The earlywood fibers from first thinnings had more large pores than the other fiber fractions. In the region of the smaller pores, the pore volume did not change significantly with refining, whereas in the region of the larger pores it increased markedly. In all the fractions investigated, specific hydrolytic enzymes hydrolyzed cellulose more easily after refining. This is an indication of an increase in cellulose surface area and/or disordering of cellulose as a result of refining, probably due to local disorder of the cellulose in the fibril aggregates. Bonding developed most strongly for the earlywood fiber fraction from first thinnings. This is concluded to be due to a combination of fiber dimensions and fiber wall porosity.
48
Sarıkaya, Engin, and Hakan Demirel. "Development of cellulose-based toys with moulded fibre production method." BioResources 15, no. 3 (July 21, 2020): 6902–11. http://dx.doi.org/10.15376/biores.15.3.6902-6911.
Анотація:
In this work, a toy was developed from bleached sulphate pulp via a moulded fibre production technique. Moulded fibre products are generally used to preserve main products from damage during transportation and stow them in a particular order. This work investigated the use of moulded fibre products in daily life as final products. Bleached softwood sulphate pulp was used for the experiments to avoid the potential hygiene problems of using recycled paper for toy production. The physical properties of different degrees of refined sulphate pulp were evaluated during toy sample production. The results indicated that toys produced with bleached softwood sulphate pulp had optimum compression strength (22 kpgf) at the 35 SR° freeness level. Produced prototypes satisfied EN 71-3:2013+A1(2014) in terms of migration element limits.
49
Mortha, Gérard, Jennifer Marcon, David Dallérac, Nathalie Marlin, Christophe Vallée, Nadège Charon, and Agnès Le Masle. "Depolymerization of cellulose during cold acidic chlorite treatment." Holzforschung 69, no. 6 (August 1, 2015): 731–36. http://dx.doi.org/10.1515/hf-2014-0270.
Анотація:
Abstract A cold holocellulose treatment (cHolT) was studied on a bleached kraft pulp (BKP) of Eucalyptus to observe the degradation of polysaccharides in pulp by chlorite at room temperature under conditions of slightly acidic pH and high chlorine charge (313% of active chlorine on BKP). Based on literature data, cellulose depolymerization is expectable by chlorite treatments at 70°C and reinforced chlorite charge, while the addition of dissolved lignin could protect cellulose. In the present study, polysaccharide degradation was followed by TAPPI viscosity, size-exclusion chromatography coupled to multidetectors, pulp yield, kappa number, elemental sugar analysis of pulps, and total organic carbon detection in filtrates. cHolTs were repeated several times without significant polysaccharide degradation, but the insertion of a caustic extraction stage at 70°C induced little degradation. This study opens the way to the setup of inert delignification procedures to be applied on raw or processed lignocellulosic samples from biorefinery studies.
50
Vänskä, Emilia, and Tapani Vuorinen. "Effect of cellulase-assisted refining on the thermal degradation of bleached high-density paper." Holzforschung 69, no. 6 (August 1, 2015): 703–12. http://dx.doi.org/10.1515/hf-2014-0194.
Анотація:
Abstract Pulp was treated with cellulase, and the chemical, physical, and optical properties of the refined pulps in paper sheets were measured in terms of the degree of polymerization of cellulose, tensile strength, elongation, burst strength, light scattering, and brightness. The sheets were thermally treated for 20 and 60 min at 225°C in the presence of 1% and 75% (v/v) water vapor. The cellulase treatment intensified the fibrillation of fibers and reduced the specific energy consumption during refining. It was demonstrated based on the water retention value that the refining modified the water-bonding ability of the pulp fibers, which was further enhanced in the case of cellulase-treated pulps. However, the enzymatic pretreatment impaired the physical properties, such as the tensile strength, elongation, and burst strength of the high-density paper. These changes further reduced the thermal strength stability of the paper. In addition, considerable brightness loss of the cellulase-treated high-density paper was observed compared to the reference paper, indicating more severe thermal degradation reactions as a consequence of enzyme-assisted refining.