softwood pulp
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2021 ◽  
Vol 3 ◽  
Author(s):  
Nicklaus Carter ◽  
Isabelle Grant ◽  
Marley Dewey ◽  
Mary Bourque ◽  
David J. Neivandt

Cellulose nanomaterials are produced employing a multitude of methodologies including electrospinning, bacterial generation, acid digestion, and a variety of mechanical defibrillation techniques; the morphology of the nanomaterial produced is specific to the production process. Feedstocks range from various forms of woody biomass, to fungi, and have a great impact on the resulting product. The mechanical defibrillation technique, such as that employed in the present work, continuously breaks down cellulose fibers suspended in water via segmentation and defibrillation through grinding and refining. The process is typically operated until a desired level of fines is achieved in the resultant slurry of cellulose nanofiber (CNF), alternatively known as cellulose nanofibril. Mechanical defibrillation processes can be built to produce several liters in a small batch system or up to tons per day in a continuous pilot scale refiner system. In the present work a continuous system was developed with the capacity to produce 14 L of cellulose nanofiber slurry with consistent specifications and in a manner compliant with GMP/GLP protocols in order to be amenable to biomedical applications. The system was constructed within an ISO class 7 cleanroom and refining was performed on bleached softwood pulp suspension in purified water. This manuscript details the continuous grinding system, the processes employed to produce cellulose nanofiber, and characterizes the resultant cellulose nanofiber slurry and sheets formed from the slurry.


2021 ◽  
Vol 55 (9-10) ◽  
pp. 1083-1094
Author(s):  
DIMITRINA TODOROVA ◽  
◽  
VESKA LASHEVA ◽  

The aim of the present work has been to study the influence of chitosan addition into the composition of paper intended for documents on its ageing stability, with a view of enhancing the resistance of paper strength and optical properties over time. The chitosan solution was added during the formation of the paper sheets in various amounts: 0.2%, 1% and 2% o.d.f. Paper samples of different fibrous compositions were prepared from bleached sulphate softwood pulp (BSWP) and bleached sulphate hardwood pulp (BHWP) in the following ratios: 50% BSWP:50% BHWP, 80% BSWP:20% BHWP, 100% BSWP and 100% BHWP. Then, paper samples were subjected to accelerated thermal ageing for 24 hours at 105 °C. It was found that the use of chitosan as additive in the composition of bleached cellulose paper samples led to improved strength and hygroscopic properties. The study showed that chitosan could be used in the production of kraft document papers comprising aluminium sulphate, as the presence of aluminium sulphate had no negative effect on the action of the biopolymer. Regarding the complex evaluation of the properties of the obtained papers, it could be summarized that, for the studied fibrous compositions, the optimum amount of the additive was 1% chitosan for a fibrous composition of 50% bleached softwood pulp and 50% bleached hardwood cellulose. Therefore, preparing document paper with the addition of chitosan is a convenient procedure to enhance a number of paper properties, even after the ageing process.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jing Liu ◽  
Xin Jin ◽  
Haitang Liu ◽  
Yongzhen An ◽  
Jie Li ◽  
...  

Abstract In this investigation, softwood pulp and bleached wheat straw pulp were used as raw materials, and Calcium Sulfate Whiskers (CSW) were used as fillers. Based on the structural properties and characteristics of CSW, the printing properties of the paper with CSW, such as whiteness, opacity, pH value, uniformity, Z-direction tensile strength and surface strength, were analyzed. The results showed that CSW has low solubility, high retention and fiber-like appearance. The whiteness of the paper is the best when the filling amount of CSW is 20 %. The paper opacity of softwood pulp increases significantly, and the opacity of bleached wheat straw pulp decreases significantly when CSW is more than 30 %. The addition reduces pH and surface strength of the paper. The evenness of the paper does not change obviously. The Z-direction tensile strength of the paper decreases in the softwood paper, but increases obviously in the bleached wheat straw paper.


TAPPI Journal ◽  
2021 ◽  
Vol 20 (9) ◽  
pp. 553-563
Author(s):  
MD. MOSTAFIZUR RAHMAN ◽  
FRANTISEK POTUCEK

This study investigates the influence of the degree of delignification of kraft spruce pulp cooked at seven different kappa numbers, ranging from 18.1 to 50.1, on the efficiency of displacement washing under laboratory conditions. Although the pulp bed is a polydispersive and heterogeneous system, the correlation dependence of the wash yield and bed efficiency on the Péclet number and the kappa number of the pulp showed that washing efficiency increased not only with an increasing Péclet number, but also with an increasing kappa number. The linear dependence between the mean residence time of the solute lignin in the bed and the space time, which reflects the residence time of the wash liquid in the pulp bed, was found for all levels of the kappa number. Washing also reduced the kappa number and the residual lignin content in the pulp fibers.


Author(s):  
Mithuna M

Abstract: Soilless substrates have many advantages over soil based system as they provide optimal conditions for plant growth when compared to soil-based agricultural practices. Different substrates are currently being used as support to the root system of plant. Substrates can be organic such as peat, bark, bagasse, sawdust, rice hulls, wood chips, etc. They can be inorganic mineral based such as sand, gravel, perlite, and stone wool slab. As the second phase of an earlier work by one of the authors on softboard as a novel wood fibre-based substrate for hydroponic systems, the present study was carried out to explore the effects of biochar amendment to wood pulps (or pulp wastes generated from fiberboard factories), on seed germination and seedling growth of Green gram (Phaseolus aureus) crop. The study also included a comparison of seedling growth in hardwood pulp and softwood pulp and to select the most suitable one for container cultivations. Keywords: Sawdust, biochar, wood pulp, green gram, container cultivation


2021 ◽  
Author(s):  
Ravikant A Patil ◽  
van Heiningen Adriaan

Abstract The objective of this work was to determine the effect of sodium methyl mercaptide (SMM) on the minimization of peeling reactions of southern pine chips in the kraft pulping process. Two methods were evaluated for SMM addition to the pulping process: 1) pre-treatment before pulping or 2) co-addition with white liquor. The effect of SMM charge, pre-treatment temperature and time, and pH of pre-treatment liquor was studied. The experimental results showed about 1.5 to 2.5 % (on O.D. (oven dry) wood basis) increase in the pulp yield after pre-treatment with or co-addition of 4.38% SMM (on O.D. wood basis). The use of 4.38% SMM allowed a decrease of the white liquor effective alkali charge (EA, on O.D. wood basis) by 3%. 4.38% SMM charge seemed to be optimum for the pre-treatment. Pre-treatment at lower pH resulted in a significant decrease in yield and an increase in rejects. The increase in pulp yield was mostly due to the increased retention of cellulose and xylan. The retention of galactoglucomannan was negligible. About 80% of the cellulose yield increase is due to the suppression of primary peeling. The remainder (0.3–0.4% of the yield increase (on O.D. wood basis) is due to reduced alkaline hydrolysis and subsequent secondary peeling.


BioResources ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. 5350-5360
Author(s):  
Antti Korpela ◽  
Aayush Kumar Jaiswal ◽  
Jaakko Asikainen

Alkyl ketene dimer (AKD) and rosin sizing are used in papermaking to decrease paper’s tendency to absorb liquid water. Earlier information regarding the effects of internal sizing on paper dry strength is not consistent. In the present laboratory study, AKD sizing of handsheets made from Nordic bleached softwood pulp (NBSK), and rosin sizing of handsheets made from Nordic hardwood chemi-thermomechanical pulp (CTMP) were done via an internal sizing method, and by immersing handsheets in aqueous sizing agent dispersion. In the study, AKD sizing had no significant effect on the dry strength of NBSK handsheets. The result corresponds to practical experiences of papermakers. However, both AKD sizing methods resulted in a substantial and long-lasting increase of handsheet wet-strength. Unlike internal AKD sizing of NBSK handsheets, rosin internal sizing of CTMP handsheets resulted in decreased handsheet dry strength. The decrease indicates that, under the conditions present during the experiment, rosin sizing agents interfered with interfiber hydrogen bonding of CTMP fibers. Given that, in practice, no such undesired effects have been commonly linked to rosin sizing, the observed effect may be specific to sheet-making conditions. However, the effect of rosin sizing on strength properties and their variation cannot be ruled out completely.


TAPPI Journal ◽  
2021 ◽  
Vol 20 (4) ◽  
pp. 241-251
Author(s):  
HO-GYUNG GU ◽  
BYUNG-GUL MIN ◽  
JI-YOUNG LEE ◽  
SEE-HAN PARK ◽  
MIN-SEOK LEE ◽  
...  

Refiner plates made using sand casting have a draft angle, which results in a trapezoidal bar shape. These trapezoidal bar plates have a limited throughput compared to the vertical bar plates, and eventually the edges of the bars become dull, resulting in longer time to reach the target freeness and shorter service life. The new light-weight refiner plate with a bar insertion method into a plate base was developed by selecting an aluminium-based alloy as the plate base material and a stainless steel alloy with high wear resistance as the bar material. The light-weight plate with sharp bar edges was very effective in reducing refining energy by reaching the target freeness faster than the sand-cast bar plate. Finally, the lightweight sharp bar plate, which weighed only about half the weight of the cast bar plate, was expected to significantly contribute to easy replacement, improved paper quality, and larger throughput without excessive loss of fiber length.


2021 ◽  
Vol 55 (3-4) ◽  
pp. 263-270
Author(s):  
JUHA FISKARI ◽  
OLGA DERKACHEVA ◽  
TUOMAS KULOMAA

"In our previous work, we demonstrated how lignin condensation and precipitation taking place in kraft pulping can be detected and even quantified by Fourier Transform Infrared (FTIR) spectroscopy. Because lignin reactions in acid sulfite pulping are very different from those occurring during kraft cooking, a new analysis method is proposed to rapidly analyze the condensed lignin in acid sulfite pulp. This kind of analysis is useful for sulfite pulp mills to detect the elevated risk of black cook. This paper presents and discusses the novel method using FTIR spectroscopy to rapidly analyze lignin condensation in softwood pulp samples from acid sulfite processes. Several softwood pulp samples from acid sulfite pulping at varying levels of condensation were included in this research. According to the results, FTIR spectroscopy allows indirect quantification of lignin condensation in a difficult matrix of wood constituents, such as in incompletely delignified acid sulfite pulp."


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Thomas Harter ◽  
Ingo Bernt ◽  
Stefanie Winkler ◽  
Ulrich Hirn

AbstractScientific publications and newsfeeds recently focused on flushable wet wipes and their role in sewage system blockages. It is stated that although products are marked as flushable, they do not disintegrate after being disposed of via the toilet. In this work it is shown that wetlaid hydroentangled wet wipes lose their initially good dispersive properties during their storage in wet condition. As a consequence, we are suggesting to add tests after defined times of wet storage when assessing the flushability of wet wipes. Loss of dispersibility is found for both, wet wipes from industrial production and wipes produced on pilot facilities. We found it quite surprising that the wet wipes’ dispersibility is deteriorating after storage in exactly the same liquid they are dispersed in, i.e. water. This is probably why the effect of wet storage has not been investigated earlier. It is demonstrated that the deteriorating dispersibility of these wipes is linked to the used type of short cellulosic fibres — only wipes containing unbleached softwood pulp as short fibre component were preserving good dispersibility during wet storage. Possible mechanisms that might be responsible are discussed, e.g. long term fiber swelling causing a tightening of the fiber network, or surface interdiffusion.


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