On the relationship between fibre length, cellulose chain length and pulp viscosity of a softwood sulfite pulp

Holzforschung ◽  
2006 ◽  
Vol 60 (4) ◽  
pp. 372-377 ◽  
Author(s):  
Luc Lapierre ◽  
Jean Bouchard ◽  
Richard Berry
Keyword(s):  
Chain Length ◽  
Fibre Length ◽  
Indirect Measurement ◽  
Pulp Mills ◽  
Cellulose Chain ◽  
Degree Of Polymerisation ◽  
Pulp Viscosity ◽  
Average Fibre ◽  
Sulfite Pulp ◽  
Pulp Strength

Abstract Many chemical pulp mills use pulp viscosity as an indicator of pulp strength, and some mill customers stipulate a particular viscosity threshold for the delivered product. Nevertheless, the value of the viscosity-strength relationship is often questioned, particularly as it varies with the wood species and the pulping process. To provide some insight, the viscosity, degree of polymerisation and fibre length were measured for a bleached softwood sulfite pulp segregated into different fractions with respect to fibre length using a Bauer-McNett fractionator. It was demonstrated that fractions with a longer average fibre length also had a higher degree of polymerisation and higher viscosity. The cellulose chain length in chemical pulps is approximately three orders of magnitude shorter than the fibre length, and thus a relationship between these two properties should not be expected. The possible causes of the correlation between fibre length and viscosity are discussed. In this work, viscosity appears to be an indirect measurement of the average fibre length of a pulp, which would be the direct contributor to the strength of that pulp.

Within-Tree Variation in Wood Fibre Biometry And Basic Density of the Urograndis Eucalypt Hybrid (Eucalyptus Grandis × E. Urophylla)

IAWA Journal ◽  
2006 ◽  
Vol 27 (3) ◽  
pp. 243-254 ◽  
Author(s):  
Teresa Quilhó ◽  
Isabel Miranda ◽  
Helena Pereira
Keyword(s):  
Wall Thickness ◽  
Fibre Length ◽  
Eucalyptus Grandis ◽  
Basic Density ◽  
Wood Properties ◽  
Axial Variation ◽  
Average Fibre ◽  
Length Width ◽  
Hybrid Eucalyptus ◽  
Old Trees

Within-tree variations in fibre length, width, wall thickness and wood basic density of Eucalyptus grandis × E. urophylla (urograndis) were studied in five 6.8-yr-old seedling trees and five 5.6-yr-old trees from one clone from Brazil. Samples were taken at 5%, 25%, 35%, 55%, 65% and 90% of stem height and five radial positions (10%, 30%, 50%, 70% and 90% of radius). The tree average fibre length, width and wall thickness were in seed and clone trees: 0.955 mm and 1.064 mm, 18 μm and 20 μm, 3.6 μm and 4.4 μm respectively. The axial variation of fibre dimensions was very low, while there was a consistent but small increasing trend from pith to periphery. The basic density ranged from 397–464 kg/m3 to 486–495 kg/m3 respectively in seedling and clone trees with a low variation along the stem. In comparison with other eucalypt pulpwood, e.g. E. globulus, the urograndis hybrid showed similar fibre dimensions and lower basic density. Overall the within-tree variation of these wood properties was low and age had a small impact on the variation of density and fibre dimensions.

Theoretical analysis of LC-refining – pressure screening systems in TMP

2019 ◽  
Vol 34 (1) ◽  
pp. 46-58 ◽  
Author(s):  
Jorge Enrique Rubiano Berna ◽  
Christer Sandberg ◽  
Mark Martinez ◽  
James Olson
Keyword(s):  
Fibre Length ◽  
Performance Curves ◽  
Average Fibre ◽  
Mechanical Pulps ◽  
Simulation Results ◽  
Save Energy ◽  
Relative Errors ◽  
The Impact ◽  
Screening Systems

Abstract LC refining of mechanical pulps has proven to save energy in the production of TMP pulps. However, the specific role of LC refining as part of a TMP system has not been thoroughly studied since it is difficult to conceive any particular system at industrial-scales and impractical at pilot-scales. In this study, pressure screening and LC refining models that describe fibre length distributions, together with correlations to predict refining power were used to model three basic refining systems. From the simulation results, the impact of important variables such as reject ratio, refiner gap and refining net-power was studied. Performance curves of length-weighed average fibre length were generated from simulation results and were used to assess each system behaviour and also to make comparisons between systems. Data from an industrial scale TMP mill sub-system was gathered and compared to simulation results showing relative errors between 0–18 % on the predicted variables.

Some wool characteristics of Karadi sheep in northern Iraq

1974 ◽  
Vol 83 (1) ◽  
pp. 171-174 ◽  
Author(s):  
K. E. Ghoneim ◽  
N. T. Kazzal ◽  
R. Kh. Abdallah
Keyword(s):  
Fibre Diameter ◽  
Fibre Length ◽  
Fibre Strength ◽  
Northern Iraq ◽  
Phenotypic Correlations ◽  
Average Fibre Diameter ◽  
Average Fibre

SUMMARYOne hundred and sixty-eight wool samples were collected from commercial flocks of Karadi sheep raised in the five provinces of northern Iraq. The wool characteristics dealt with were staple and fibre length, crimps, fibre diameter, medullation, fibre strength and elongation.The results showed that the Karadi wool is a long type of carpet fleece with average staple and fibre lengths of 19·3 and 23·5 cm, respectively. It had an average fibre diameter of 48·1 μ and contained 19·45 % medullated fibres. The number of crimps per 2 cm was 2·4. Average fibre strength and elongation were 24·8 g/5 cm and 31·8 % respectively. Phenotypic correlations between wool traits were studied.

Anatomy of Acacia Mangium Grown in Malaysia

IAWA Journal ◽  
1993 ◽  
Vol 14 (3) ◽  
pp. 245-251 ◽  
Author(s):  
Mohd. Hamami Sahri ◽  
Faridah Hanum Ibrahim ◽  
Nor Aini Ab. Shukor
Keyword(s):  
Age Groups ◽  
Fibre Diameter ◽  
Fibre Length ◽  
Acacia Mangium ◽  
Tropical Species ◽  
Average Percentage ◽  
Plantation Forests ◽  
Diameter Fibre ◽  
Average Fibre ◽  
Two Age Groups

A study on the tissue proportions and fibre dimensions of plantation-grown Acacia mangium was carried out. Ten selected trees from two age groups (4- and 8-year-old) were obtained from plantation forests in Selangor. Disks were taken from four sampling heights. Acacia mangium wood is diffuse-porous with mostly solitary vessels. The rays are uniseriate. The average percentage of fibres, vessels and rays of 4-year-old and 8-year-old samples are 85.8%, 9.1%, 5.2% and 84.8%, 9.8%, 5.3%, respectively. Acacia is a shortfibred tropical species. The average fibre length, fibre diameter, fibre lumen diameter and fibre wall thickness are 934, 24, 17 and 3.3 µm for 4-year-old samples and 1017,20, 12 and 4.3 µm for 8-year-old sampies, respectively. The sampies near the pith have the shortest fibres and the length increases toward the bark. Fibre length also tends to decrease with height. The vessel percentage decreases with increasing height.

The use of thyroxine to reduce average fibre diameter in fleece wool when feed intake is increased

2001 ◽  
Vol 41 (5) ◽  
pp. 611 ◽  
Author(s):  
G. J. Lee ◽  
K. J. Thornberry ◽  
A. J. Williams
Keyword(s):  
Saline Solution ◽  
Daily Intake ◽  
Fibre Diameter ◽  
Fibre Length ◽  
Treatment Groups ◽  
Average Fibre Diameter ◽  
Wool Growth ◽  
Average Fibre ◽  
Ad Libitum ◽  
The Difference

An experiment was conducted to determine whether thyroxine injections would control the increases in fibre diameter when the wool growth of Merino wethers is stimulated by an increased supply of feed. Fifty-seven sheep were allocated to 1 of 5 levels of daily intake, ranging from 0.75 maintenance to ad libitum, and injected every third day with 3 mg of L-thyroxine or a saline solution (control). Sheep treated with thyroxine had elevated plasma tri-iodothyronine (T3) levels, which were highest in sheep fed the least (P<0.01). Ad libitum intakes of sheep treated with thyroxine tended to be higher than that of control sheep, particularly in the fifth to seventh weeks of the experiment, and liveweight gain over the initial 4 weeks was significantly (P<0.001) less. Wool growth was increased by thyroxine treatment, although the difference was small in the second half of the experiment at the highest intake levels. Fibre diameter of sheep treated with thyroxine was greater at low intakes, although the difference diminished as intake increased. Fibre length in the second half of the experiment was positively related to intake, but there were no effects of thyroxine. Although the relationships of fibre diameter and length with wool growth did not differ between the treatment groups, length accounted for more of the variation in wool growth in the second half of the experiment in treated wethers than in control wethers (0.376 v. 0.182 of the variation, respectively). Thyroxine did not appreciably reduce the extent of the increase in fibre diameter associated with an increase in the availability and intake of feed.

The effects of breed, crossbreeding and other factors on variation in fleece and skin traits

1980 ◽  
Vol 30 (3) ◽  
pp. 417-429 ◽  
Author(s):  
J. A. Woolliams ◽  
G. Wiener
Keyword(s):  
Unit Area ◽  
Fibre Diameter ◽  
Fibre Length ◽  
Live Weight ◽  
Strong Relationship ◽  
Average Fibre Diameter ◽  
Wide Range ◽  
Average Fibre ◽  
Fleece Weight ◽  
The Relationship

ABSTRACTBreed and crossbreeding significantly affected variation in 10 fleece, follicle density and fibre diameter traits in 12-week-old lambs. The breeds involved were the Scottish Blackface, South Country Cheviot, Welsh Mountain, Lincoln Longwool, Southdown and Tasmanian Merino, but the last only by rams.The Southdown came closest to the Merino in affecting density and diameter traits although the Merino crosses remained clearly distinguishable by their high follicle density. The Lincoln and Blackface crosses were notable for their long fibres and the Blackface crosses also had the least dense follicle and coarsest primary fibres. The coarsest secondary fibres were from Lincoln and Cheviot crosses. Heterosis estimates were obtained for crosses involving the Blackface, Cheviot, Welsh and Lincoln breeds. Significant heterosis was present in a wide range of traits but was not apparent in all crosses. Maternal differences were evident for many of the traits but with density these differences were apparently related to maternal effects on live weight of the lamb. The sex of the lamb, its birth type and rearing and its 12-week live weight significantly affected many of the traits.Among breeds and crosses a strong relationship was found between fibre density and average fibre diameter. The relationship suggested that breed variation in total fibre area per unit area of skin was small compared with the breed variation in its components. Fleece weight per unit area was most closely related to mean fibre length.

Wool yield and characteristics of Dorset, Leicester and Sunffolk breeds and their ‘DLS’ cross

1977 ◽  
Vol 88 (3) ◽  
pp. 651-653 ◽  
Author(s):  
M. H. Fahmy ◽  
J. A. Vasely
Keyword(s):  
First Generation ◽  
Fibre Diameter ◽  
Fibre Length ◽  
Wool Production ◽  
Average Fibre Diameter ◽  
Average Fibre ◽  
Wool Yield ◽  
Fleece Weight

SUMMARYGreasy fleece weight (12 months growth) and wool samples from hip and shoulder regions were taken on 15 Dorset, 20 Leicester, 20 Suffolk and 17 DLS ewes (a cross of ½ Dorset, ¼ Leicester, ¼ Suffolk obtained by mating DL rams to DS ewes and DS rams to DL ewes). The purpose of the study was to compare wool production and characteristics of the first generation of DLS with that of the three breeds of origin. Wool production of DLS was 3·58 kg, 8·8 and 14% higher than that of Suffolk and Dorset, but 11% lower than that of Leicester (P< 0·01). The percentage of clean wool was highest in Leicester (78·3%), followed by DLS, Dorset and Suffolk (76·1, 74·3 and 70·5%, respectively). The average fibre diameter of the DLS and Leicester was 38 /m, 4 /m thicker than that for Suffolk and Dorset (P < 0·01). Average fibre length was 15 cm in DLS and Dorset, 6 cm shorter than in Leicester, and 3 cm longer than in Suffolk (P < 0·01). The variability in fibre diameter and length was highest in Leicester, followed closely by DLS.

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