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

Study on Effort of Ultrasonic Treatment on Water Retention Value of Pulp Fiber

2014 ◽  
Vol 1030-1032 ◽  
pp. 458-461
Author(s):  
Quan Xiao Liu ◽  
Dan Xi Li ◽  
Wen Cai Xu
Keyword(s):  
Ultrasonic Treatment ◽  
Processing Time ◽  
Water Retention ◽  
Wood Pulp ◽  
Pulp Fiber ◽  
Ultrasonic Power ◽  
Pulp Fibers ◽  
Water Retention Value ◽  
Absorbent Cotton ◽  
Coniferous Wood

Effects of ultrasonic processing conditions on water retention value of bleaching coniferous wood pulp fibers, absorbent cotton pulp fiber and straw pulp fiber were discussed. Results showed that ultrasonic power and processing time have an significant impact on water retention value of three kinds of pulp, the effort of ultrasonic treatment temperature on water retention value of three kinds of pulp is less. The water retention value of bleaching coniferous wood pulp fibers, absorbent cotton pulp fiber and straw pulp fiber, respectively, reach the maximum at power of 300W, 500W, 400W, and processing time of 60min, 120min, 60min.

Water retention value for characterizing fibrillation degree of cellulosic fibers at micro and nanometer scales

Cellulose ◽  
2018 ◽  
Vol 25 (5) ◽  
pp. 2861-2871 ◽  
Author(s):  
Feng Gu ◽  
Wangxia Wang ◽  
Zhaosheng Cai ◽  
Feng Xue ◽  
Yongcan Jin ◽  
...  
Keyword(s):  
Water Retention ◽  
Water Retention Value ◽  
Cellulosic Fibers

Study on Mercerization Orthogonal Experiment of Coniferous Wood Pulp Fiber

2014 ◽  
Vol 1030-1032 ◽  
pp. 454-457
Author(s):  
Quan Xiao Liu ◽  
Dan Xi Li ◽  
Wen Cai Xu
Keyword(s):  
Water Retention ◽  
Orthogonal Experiment ◽  
Wood Pulp ◽  
Pulp Fiber ◽  
Pulp Fibers ◽  
Water Retention Value ◽  
Treatment Conditions ◽  
Fiber Cell Wall ◽  
Coniferous Wood ◽  
Wood Pulp Fiber

Effects of mercerizing treatment on water-retention value of bleaching coniferous wood pulp fibers were discussed and the mercerizing treatment conditions were optimized. The best conditions of mercerizing treatment is NaOH concentration of 7mol/L, temperature of 40°C and processing time of 100min. SEM showed that the fiber cell wall swelling increase after mercerization.

The Use of Novel F-RAFT Agents in High Temperature and High Pressure Ethene Polymerization: Can Control be Achieved?

2007 ◽  
Vol 60 (10) ◽  
pp. 788 ◽  
Author(s):  
Markus Busch ◽  
Marion Roth ◽  
Martina H. Stenzel ◽  
Thomas P. Davis ◽  
Christopher Barner-Kowollik
Keyword(s):  
Molecular Weight ◽  
High Pressure ◽  
High Temperature ◽  
Degree Of Polymerization ◽  
Molecular Weight Distributions ◽  
High Pressure High Temperature ◽  
Reversible Addition ◽  
Weight Distributions ◽  
Raft Agent ◽  
Initial Results

Simulations are employed to establish the feasibility of achieving controlled/living ethene polymerizations. Such simulations indicate that reversible addition–fragmentation chain transfer (RAFT) agents carrying a fluorine Z group may be suitable to establish control in high-pressure high-temperature ethene polymerizations. Based on these simulations, specific fluorine (F-RAFT) agents have been designed and tested. The initial results are promising and indicate that it may indeed be possible to achieve molecular weight distributions with a polydispersity being significantly lower than that observed in the conventional free radical process. In our initial trials presented here (using the F-RAFT agent isopropylfluorodithioformate), a correlation between the degree of polymerization and conversion can indeed be observed. Both the lowered polydispersity and the linear correlation between molecular weight and conversion indicate that control may in principle be possible.

Effects of a PFI refiner’s operational parameters on the swellability of recycled fiber

TAPPI Journal ◽  
2020 ◽  
Vol 19 (5) ◽  
pp. 239-246
Author(s):  
XIAONING SHEN ◽  
BO LI ◽  
WENXUAN MO ◽  
XIN-SHENG CHAI
Keyword(s):  
Water Retention ◽  
Fiber Quality ◽  
Operational Parameters ◽  
Fiber Morphology ◽  
Water Retention Value ◽  
Electron Microscopic ◽  
Mathematical Relation ◽  
Scanning Electron Microscopic ◽  
Recycled Fiber ◽  
Scanning Electron

This paper presents data on the effects of operational parameters (number of revolutions, linear pressure, and gap) of the PFI refiner on the swellability of recycled fiber, which was characterized by water retention value (WRV). The results showed that the increase of recycled fiber’s WRV was proportional to the number of revolutions and the linear pressure, but inversely proportional to the gap. The mathematical relation between these parameters and the fiber WRV could be described by an empirical model for gaps greater than 0.1 mm. Scanning electron microscopic images of fiber morphology showed that the basic framework of fibers could be maintained with the gap greater than 0.1 mm, but was destroyed with smaller gaps. This model provides a technical reference for quantitative control of refining treatment and an effective method for improving recycled fiber quality.

New model for predicting tensile strength and density of eucalyptus handsheets based on an activation parameter calculated from fiber distribution characteristics

Holzforschung ◽  
2010 ◽  
Vol 64 (2) ◽  
Author(s):  
Iiro Pulkkinen ◽  
Juha Fiskari ◽  
Ville Alopaeus
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Wall Thickness ◽  
Water Retention ◽  
Activation Parameter ◽  
Water Retention Value ◽  
Data Set ◽  
Network Activation ◽  
Fiber Wall ◽  
Fiber Segment

Abstract The activation parameter developed is based on the fiber wall thickness distribution, fiber curl distribution, and water retention value of the unrefined fibers. The mechanical properties of paper that contain chemical pulp depend, among other things, on the free fiber segment activation between fiber-fiber crossings that is created during drying. Experimental data revealed that the degree of fiber swelling is responsible together with the fiber shape factor (curl) and fiber wall thickness for the extent of fiber network activation. The amount of bonding between fibers also affects fiber segment activation. Based on the experimental data, it was deduced that interfiber bonding ability of fibers, characterized as the water retention value, was mainly responsible for the development of handsheet density. Tensile index development was more affected by the morphology of fibers, which was the main determinant for high activation potential of fibers. Factor analysis was used to identify the main causes of variation for a refining data set of 20 Eucalyptus grandis samples. Three independent descriptors were found to be responsible for the majority of the variation: the bonding and activation factor, the factor of microcompressions, and the factor of fiber wall thickness and fiber curl. The activation parameter developed in this study can be used to determine the effect of fiber segment activation and inter-fiber bonding on the inplane mechanical properties of paper.

Recycled fiber treated with NaOH/urea aqueous solution: effects on physical properties of paper sheets and on hornification

2018 ◽  
Vol 33 (4) ◽  
pp. 651-660 ◽  
Author(s):  
Yingju Miao ◽  
Yunfei Zhi ◽  
Heng Zhang ◽  
Ying Chen ◽  
Shaoyun Shan ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Physical Properties ◽  
Water Retention ◽  
Crystalline Region ◽  
Cellulose Film ◽  
Reinforced Concrete Structure ◽  
Water Retention Value ◽  
Fiber Network ◽  
Urea Aqueous Solution ◽  
Intramolecular Hydrogen

Abstract Hydrogen bonding among fiber microfibrils is the primary cause of fiber hornification, wherein NaOH/urea aqueous solution precooled to −13 °C can disassemble inter- and intramolecular hydrogen bonds. Whether hornified fibers treated with this process can significantly improve fiber swelling ability and physical properties of the resulting paper sheets remains a problem. In this investigation, the 6th cycle fiber was pretreated with this procedure, and the water retention value of the fiber before and after treatment and the physical properties of the resulting paper sheets were studied. The results indicate that the lignin decline, complete swelling of flat fiber, filling of cellulose film between the interfiber network, and decreasing crystalline region all contribute to the increase in water retention value. The water retention value of repaired fiber is equivalent to that of virgin pulp, and hornification reverses by 89 %. In addition, the cellulose film filling among the fiber network constructs a similar reinforced concrete structure, which causes the tear, burst, and tensile index of the resulting paper sheets to increase by 145 %, 98 %, and 43 %, respectively.

scholarly journals Study on MMA and BA Emulsion Copolymerization Using 2,4-Diphenyl-4-methyl-1-pentene as the Irreversible Addition–Fragmentation Chain Transfer Agent

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 80
Author(s):  
Zuxin Zhang ◽  
Daihui Zhang ◽  
Gaowei Fu ◽  
Chunpeng Wang ◽  
Fuxiang Chu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Tensile Properties ◽  
Chain Transfer ◽  
Monomer Conversion ◽  
Degree Of Polymerization ◽  
Polymerization Rate ◽  
Chain Transfer Agent ◽  
Regulation Mechanism ◽  
Transfer Coefficients ◽  
Emulsion Copolymerization

As a chain transfer agent, 2,4-diphenyl-4-methyl-1-pentene (αMSD) was first introduced in the emulsion binary copolymerization of methyl methacrylate (MMA) and butyl acrylate (BA) based on an irreversible addition–fragmentation chain transfer (AFCT) mechanism. The effects of αMSD on molecular weight and its distribution, the degree of polymerization, polymerization rate, monomer conversion, particle size, and tensile properties of the formed latexes were systematically investigated. Its potential chain transfer mechanism was also explored according to the 1H NMR analysis. The results showed that the increase in the content of αMSD could lead to a decline in molecular weight, its distribution, and the degree of polymerization. The mass percentage of MMA in the synthesized polymers was also improved as the amounts of αMSD increased. The chain transfer coefficients of αMSD for MMA and BA were 0.62 and 0.47, respectively. The regulation mechanism of αMSD in the emulsion polymerization of acrylates was found to be consistent with Yasummasa’s theory. Additionally, monomer conversion decreased greatly to 47.3% when the concentration of αMSD was higher than 1 wt% due to the extremely low polymerization rate. Moreover, the polymerization rate was also decreased probably due to the desorption and lower reactivity of the regenerative radicals from αMSD. Finally, the tensile properties of the resulting polyacrylate films were significantly affected due to the presence of αMSD.

scholarly journals Is Molecular Weight or Degree of Polymerization a Better Descriptor of Ultrasound-Induced Mechanochemical Transduction?

2016 ◽  
Vol 5 (2) ◽  
pp. 177-180 ◽  
Author(s):  
Preston A. May ◽  
Nicholas F. Munaretto ◽  
Michael B. Hamoy ◽  
Maxwell J. Robb ◽  
Jeffrey S. Moore
Keyword(s):  
Molecular Weight ◽  
Degree Of Polymerization ◽  
Mechanochemical Transduction

Use of Cellulose-Containing Fillers in Composites with Polypropylene

1970 ◽  
Vol 17 (2) ◽  
pp. 150-154
Author(s):  
Marianna LAKA ◽  
Svetlana CHERNYAVSKAYA ◽  
Galia SHULGA ◽  
Viktor SHAPOVALOV ◽  
Andrej VALENKOV ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Shear Modulus ◽  
Rapeseed Oil ◽  
Water Retention ◽  
Raw Materials ◽  
Water Retention Value ◽  
Water Vapour Sorption ◽  
Recycled Polypropylene ◽  
Sulphate Pulp

The composites, containing recycled polypropylene and fillers, obtained from different lignocellulosics by the thermocatalytic destruction method, were investigated. Birch sawdust, newsprint wastes, cotton residues and wood bleached sulphate pulp were used as raw materials for obtaining fillers. The indices of mechanical properties (tensile strength, modulus of elasticity, deformation at break, shear modulus, toughness, twisting moment) of the composites' samples were determined. It has been found that the obtained composites have relatively good mechanical properties. Better results were obtained, using fillers from sawdust and wood pulp. After treating the fillers with rapeseed oil, their water vapour sorption and water retention value (WRV) decreased. In this case, the strength of the composites was higher.http://dx.doi.org/10.5755/j01.ms.17.2.484

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