scholarly journals Improving dissolving wood pulp quality using Brown-stock fractionation

2018 ◽  
Author(s):  
◽  
Marvin Sydney Potgieter
Keyword(s):  
Chlorine Dioxide ◽  
Wood Pulp ◽  
Pulp Fibres ◽  
Production Stages ◽  
Dissolving Pulps ◽  
Early Production ◽  
Pulp Properties ◽  
Viscose Process

Dissolving wood pulp (DWP) contains high levels of cellulose and has various applications. Production of dissolving wood pulp is accompanied by various challenges such as equipment operational problems and high bleaching costs. These are mainly due to lignin and other impurities contained in wood. Further, these impurities impose threats to the dissolving pulps applications such as the viscose process and the manufacture of finished rayon products. Removal of these contaminants at the early production stages proved effective in meeting by the challenges. Hydrocyclones achieve the separation of heavy and light pulp components in a process known as fractionation. In the case of dissolving wood pulp, hydrocyclones fractionate the pulp fibres into coarse fibres and fine fibres known as fines. Fines are the reject materials and are associated with impurities such as wood resins. Wood pulp was fractionated at 0.8% consistency using a Kadant laboratory hydrocyclone at mass reject rates of 5% and 11%. Pulp properties and application properties were determined and compared to unfractionated pulp. The fractionated pulps showed higher cellulose contents and lower levels of fines and associated resins. Bleaching of the fractionated pulps under a standard ODEDH bleaching sequence showed higher levels of delignification, as measured by brightness, and more favourable application properties. These findings were used to optimise the bleaching sequence by reducing the amount of chlorine dioxide applied in the second chlorine dioxide stage. The optimised bleaching sequence produced pulps with satisfactory fibre and application properties.

scholarly journals In situ SEM micro-indentation of single wood pulp fibres in transverse direction

2010 ◽  
Vol 59 (5) ◽  
pp. 345-349 ◽  
Author(s):  
R.-B. Adusumalli ◽  
R. Raghavan ◽  
P. Schwaller ◽  
T. Zimmermann ◽  
J. Michler
Keyword(s):  
Transverse Direction ◽  
Wood Pulp ◽  
Pulp Fibres ◽  
Micro Indentation

Quantification of water in different states of interaction with wood pulp fibres

Cellulose ◽  
1996 ◽  
Vol 3 (1) ◽  
pp. 189-202 ◽  
Author(s):  
U. Weise ◽  
T. Maloney ◽  
H. Paulapuro
Keyword(s):  
Wood Pulp ◽  
Pulp Fibres

Three-dimensional visualization of confocal images of wood pulp fibres

1992 ◽  
Vol 11 (21) ◽  
pp. 1416-1418 ◽  
Author(s):  
A. G. Robertson ◽  
H. F. Jang ◽  
R. S. Seth
Keyword(s):  
Three Dimensional ◽  
Wood Pulp ◽  
Pulp Fibres ◽  
Confocal Images

Characterization of dissolving pulp by fibre swelling in dilute cupriethylenediamine (CUEN) solution in a MorFi analyser

Holzforschung ◽  
2016 ◽  
Vol 70 (7) ◽  
pp. 611-617 ◽  
Author(s):  
Benoît Arnoul-Jarriault ◽  
Raphaël Passas ◽  
Dominique Lachenal ◽  
Christine Chirat
Keyword(s):  
Crystalline Form ◽  
Dissolving Pulp ◽  
Kraft Pulps ◽  
Fibre Structure ◽  
Birch Wood ◽  
Eucalyptus Wood ◽  
Cold Caustic Extraction ◽  
Dissolving Pulps ◽  
Viscose Process

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.

An XPS round robin investigation on analysis of wood pulp fibres and filter paper

2005 ◽  
Vol 584 (1) ◽  
pp. 126-132 ◽  
Author(s):  
Leena-Sisko Johansson ◽  
J.M. Campbell ◽  
Pedro Fardim ◽  
Anette Heijnesson Hultén ◽  
Jean-Philippe Boisvert ◽  
...  
Keyword(s):  
Filter Paper ◽  
Wood Pulp ◽  
Round Robin ◽  
Pulp Fibres

scholarly journals REVIEW ON PHOTOGRAMMETRIC SURFACE INSPECTION IN AUTOMOTIVE PRODUCTION

2021 ◽  
Vol XLIII-B2-2021 ◽  
pp. 511-518
Author(s):  
M. Hödel ◽  
L. Hoegner ◽  
U. Stilla
Keyword(s):  
Deep Learning ◽  
Machine Vision ◽  
Data Driven ◽  
Quality Data ◽  
Surface Inspection ◽  
Production Environment ◽  
Production Chain ◽  
Production Stages ◽  
Early Production ◽  
Automotive Production

Abstract. When purchasing a premium car for a substantial sum, first impressions count. Key to that first impression is a flawless exterior appearance, something self-explanatory for the customer, but a far greater challenge for production than one might initially assume. Fortunately, photogrammetric technologies and evaluation methods are enabling an ever greater degree of oversight in the form of comprehensive quality data at different automotive production stages, namely stamping, welding, painting and finishing. A drawback lies in the challenging production environment, which complicates inline integratability of certain technologies. In recent years, machine vision and deep learning have been applied to photogrammetric surface inspection with ever increasing success. Given comprehensive surface quality information throughout the entire production chain, production parameters can be dialed in ever tighter in a data-driven fashion, leading to a sustainable increase in quality. This paper provides a review of current and potential contributions of photogrammetry to this end, discussing several recent advances in research along the way. Particular emphasis will be placed on early production stages, as well as the application of machine vision and deep learning to this challenging task. An outline for further research conducted by the authors will conclude this paper.

scholarly journals Assessing wood pulp reactivity through its rheological behavior under dissolution

Cellulose ◽  
2019 ◽  
Vol 26 (18) ◽  
pp. 9877-9888
Author(s):  
Sara Ceccherini ◽  
Thad Maloney
Keyword(s):  
Molecular Weight ◽  
Water Retention ◽  
Wood Pulp ◽  
Degree Of Polymerization ◽  
Cellulose Dissolution ◽  
Water Retention Value ◽  
Cellulosic Fibers ◽  
Measurement Protocol ◽  
Convenient Approach ◽  
Viscose Process

Abstract Recent years have witnessed an increasing interest in man-made cellulosic fibers, whose production generally requires cellulose dissolution and regeneration. Cellulosic fibers are difficult to dissolve. Thus, the recalcitrance of wood pulp can be an estimate of its reactivity. Pulp reactivity is usually assessed via complex and time-consuming laboratory simulations of the viscose process. This study proposes a faster and more convenient approach. The dissolution-based torque reactivity (DTR) test measures the evolution of the rheological properties of a pulp suspension under dissolution in cupriethylenediamine. Reactivity is quantified in terms of initial dissolution rates (IDR) and dissolution times (DT). This study describes the measurement protocol for the DTR test and its application to some commercial pulps and a series of pulps hornified to different extents. The IDR and DT values were compared with other pulp features, including degree of polymerization, molecular weight distribution, specific surface area and water retention value. The DTR test proved to be reasonably precise and fast to carry out. Graphic abstract

ECF Bleaching of Pre-Hydrolyzed Larix Kraft Pulp for Production of Dissolving Pulp

2013 ◽  
Vol 634-638 ◽  
pp. 386-390
Author(s):  
Zhi Li ◽  
Jun Li ◽  
Jun Xu
Keyword(s):  
Hydrogen Peroxide ◽  
Chlorine Dioxide ◽  
Kraft Pulp ◽  
Kappa Number ◽  
Alkaline Extraction ◽  
Polymerization Degree ◽  
Oxygen Delignification ◽  
Elemental Chlorine ◽  
Pulp Properties ◽  
Ecf Bleaching

Elemental Chlorine Free (ECF) bleaching sequence of O1/O2D0EOPD1D2 was adopted to bleach the pro-hydrolyzed Larix kraft pulp, where O1/O2 was two-stage oxygen delignification without interstage treatment, D was chlorine dioxide bleaching, EOP was pressurized alkaline extraction strengthened by hydrogen peroxide. Keeping bleaching temperature and time unchanged, sodium hydroxide charge(NaOH) in O1 stage, chlorine dioxide(ClO2) charge in D0 stage and D2 stage were studied, pulp properties such as brightness, kappa number, alpha-cellulose, pentosan and polymerization degree were measured and compared to establish optimal bleaching conditions. Results show that the optimal charge of NaOH in O1 stage is 2.5%, ClO2 in D0 and D2 stage are 2.5%, 0.6%, and the pulp gained at the optimal bleaching conditions has the properties of 93.9% of alpha-cellulose, 2.60% of pentosan, 375.5 ml/g of viscosity and 86.6%ISO of brightness.

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