Showing papers in "Appita Journal in 2000"

Variation of microfibril angle, density and fibre orientation in twenty-nine Eucalyptus nitens trees

Abstract: SilviScan-2 was used to estimate and map microfibril angle (MFA) and density in twenty-nine 15-year-old Eucalyptus nitens trees. Over 4000 MFA measurements were made at about 100/hour. Each measurement represented a weighted average for about 50000 fibres. After an initial decrease near ground level, density increased with height in the stem. MFA decreased with height in the stem, reached a minimum around 30 to 50% of tree height, then increased towards the top. In the radial direction, density first decreased for a few years, then increased towards the bark. MFA was in the range 20 to 30 degrees near the pith at all heights and generally decreased towards the bark over most of the height of the stem. The lowest MFA values (approx. 10 degrees) were found close to the bark at 30 to 50% of stem height. Both density and MFA varied more rapidly near ground level, increasing the uncertainty of correlations between breast-height properties and whole tree properties. On some samples, high-resolution (0.2 mm) MFA scans were performed to confirm an earlier finding that MFA is strongly inversely correlated with density over a few growth rings but not over larger distances. X-ray diffraction was also used for estimating the orientation of the fibres within the samples. The radial variation in fibre orientation generally decreased with distance from the ground. Breast-height sample properties were moderate to good predictors of whole tree properties. Better correlations were obtained using samples from 5.5 m. Whole tree average density and MFA were found to be uncorrelated, indicating that tree improvement strategies could be designed to simultaneously optimise these properties.

Applications of NIR spectroscopy to forest research

Abstract: Research conducted at CSIRO Forestry and Forest Products and the Cooperative Research Centre for Hardwood Fibre and Paper Science (CRC-HFPS) has investigated the feasibility of using near-infrared (NIR) spectroscopy as a rapid, inexpensive method for assessing the pulpwood quality of plantation eucalypts. Michell and Schimleck (1) have published a review of this research. Since that review the methodology has been utilised in a number of research applications, which are summarised in this paper. Reliable pulp yield calibrations have been developed using NIR spectroscopy. A pulp yield calibration with a yield range of only 3 percentage points has been developed. It is also demonstrated that NIR spectroscopy can be successfully applied to the selection of 'high yield' trees. Collaborative research with the CRC for Sustainable Production Forestry has investigated the influence of fertiliser application on pulp yield in Eucalyptus globulus. An investigation of genotype by environment interactions in E.globulus has also been conducted. Further collaborative research has investigated the ability of NIR spectroscopy to estimate the cellulose content of increment core samples, with the view of using cellulose content as a secondary standard for pulp yield. Several excellent calibrations for cellulose content have been developed. The influence of growth rate on pulp yield has also been investigated in trees of E.globulus and E.nitens grown on irrigated and rainfed sites. It was found that growth rate did not have a significant influence on pulp yield. This study provided a textbook example of how NIR spectroscopy can be used to provide information at relatively low cost.

The effect of fibre fibril angle on some handsheet mechanical properties

Abstract: Segments of three eucalypt trees from the same site, two Eucalyptus nitens and one E. globulus, were selectively chipped. Segments at 10%, 30% and 70% of the tree height were taken, Wood chips coming from the inner and outer parts of each segment were then separated from each other, producing six chip samples per tree. The average fibril angle of each sample was determined using confocal microscopy. After kraft pulping, fibre and handsheet properties were measured. For most samples there was a statistically significant reduction in fibril angle moving from the inner to the outer segment. However, the reduction in fibril angle from inner to outer segment was generally small (∼5° for most samples). The average fibril angle determined for each eucalypt sample lay within the range 0 to 13°. As the measured change in fibril angle for the eucalypts was so small, it was concluded that the fibril angle had had a negligible effect on fibre and sheet mechanical properties.

Quantitative analysis of paper cross-sections

Abstract: Quantitative information on the macro-pore structure of the paper sheet is provided by a new technique that analyses the sheet cross-section. The technique provides a Z-directional wall density profile, from which it is possible to infer the relative positions of fines and fibres within the sheet, as well as its two sidedness. Measures of wall area, fibre lumen area and interfibre area provide valuable information on the effects of changing furnish composition and processing variables. Cross-sections were exposed by abrading, and an image was captured from the exposed surface using a Leica TCS/NT confocal laser-scanning microscope. Images were analysed using Optimas 6.0.

Kraft pulp processing : pressure screen fractionation

Abstract: Fibre fractionation can be used to enhance or modify pulp and paper products. The fractionating capability of pressure screens, using radiata pine kraft fibre, is the focus of this investigation. A dry-lap, bleached, medium density radiata pine kraft pulp was processed through Ahlstrom Model F1 pressure screens in a single-stage pilot plant setup. Screening was conducted at 1.5% feed stock concentration and 60°C. Pressurised screening separation into fibre streams of differing quality could be achieved using both smooth-surface hole and contoured-surface fine slot baskets. Generally, a decrease in screen aperture dimension improved separation, as did a less vigorous rotor action. Contoured screen surfaces for the hole baskets, and an increase in contour height for slotted baskets, were detrimental to separation. The response to rotor speed varied for the different basket/rotor combinations, and in some cases improved operational flexibility. Increased aperture velocity tended to reduce selectivity. On balance, baskets with holes 1.60mm to 2.0mm O showed the most potential producing reasonable efficiency with minimal operational constraint.

Paper structure engineering

Abstract: The specific purpose of this article is to show how machine designs have evolved to enable better control of paper structure. Since pulp properties also have a strong influence on paper structure, another aim is to show how pulp and machine design interact. The scope of this article is to discuss paper structure control at the wet end - Z-direction distributions of filler, fines, bonding, and orientation - but not surface structure.

Wood and kraft fibre property variation within and among nine trees of Eucalyptus nitens

Abstract: Understanding the distributions of wood and fibre properties among logs within trees is of importance to the wood processor since it will allow selective log utilisation to maximise product quality and minimise processing costs. Such advantages can be at both the solidwood and reconstituted product levels. Furthermore, understanding of the levels of variation among both trees and logs will allow breeding programs/strategies and rotation ages etc. to be directed to product requirements at the log level. For nine 15-year-old E. nitens trees, the wood and kraft fibre property variation is extremely high among trees and among the four or five 5.5 m logs of each tree. Some critical property distribution trends within trees are: . Chip basic density, xylose and ash contents increase linearly with increasing height (log number) from the ground. . Chip lignin increases, and glucose content decreases, non-linearly from log 2 to the toplog, but mainly show reversed trends from log 1 to log 2. Hence, kraft pulp yields can be expected to be particularly low for logs 4 and 5. . Kraft fibre length, perimeter and coarseness initially increase from log 1 to log 2 but then decrease markedly thereafter. Hence, numbers of fibres/g are high, and handsheet bulk values particularly low for kraft pulps made from logs 4 and 5.

Peroxide application in ECF sequences : a description of the state-of-the-art

Abstract: In Elemental Chlorine Free (ECF) bleaching the reinforcement of the E stages with oxidants, O 2 and H 2 O 2 , decreases the demand for chlorine dioxide in subsequent stages. A final P stage can lower the ClO 2 demand, because much less than the oxidative equivalent amount of H 2 O 2 is required to achieve the same final brightness. Brightness stability in accelerated heat aging is improved with a final P stage. Very high temperature and pressurised conditions in the P stage cause thermal decomposition which produces pulp viscosity and yield losses. This applies for both Eop stages and final P stages. The effects of peroxide are described in terms of pulp brightness increase and chemical demands as well as bleached pulp viscosity, effluent Chemical Oxygen Demand (COD) levels and pulp yield. Optimum stage conditions are to apply moderate amounts of hydrogen peroxide at a temperature level not above 90°C. Higher temperature results in lower viscosity and higher effluent COD loads.

Simulating the forming process with the moving belt drainage former

Abstract: To accurately evaluate the papermaking potential of pulps it is necessary to reproduce, as closely as possible, machine-made sheets in the laboratory. A new laboratory sheet former, the MBDF, has been developed at Australian Pulp and Paper Institute (APPI) for producing 220 by 220 mm handsheets that reproduce certain features of commercial paper. This former uses headbox stock concentrations that are close to paper machine values, a commercial fabric, high frequency vacuum pulses and programmed vacuum profiles. This paper describes the forming process on the MBDF and discusses formation and strength properties of handsheets made on the MBDF.

The importance of the substrate surface energetics in water-based flexographic printing

Abstract: This work focuses on the effect of sizing linerboard type handsheets made from NSSC eucalypt fibres on their ink receptivity in water-based flexographic printing. Print density was used as an index that reflected the ink receptivity of the handsheets. The effect of handsheet surface roughness on print density is also considered. Some difficulties in evaluating the work of adhesion between water and the sheet are discussed.

The quantitative microscopic analysis of paper cross-sections : sample preparation effects

Abstract: A quantitative technique is being developed for the analysis of paper cross-sections. This technique provides a Z-directional profile of the sheet and measures of wall area, total pore area, interfibre pore area and lumen area. The intention is to be able to relate pulp processing conditions to sheet structure and end-use performance. With this technique paper samples are embedded in resin, cross-sections are then exposed by abrading and imaged by confocal laser scanning microscopy. The present paper investigates the effect of sample preparation on these parameters by subjecting uncalendered and calendered sheets to a number of embedding and sectioning procedures. The cross-sectional thickness of uncalendered sheets deviated from standard thickness by approximately 1 to 5%, whereas for calendered sheets, cross-sectional thickness showed a 20 to 30% increase over standard thickness. There was no evidence of fibre swelling or shrinkage resulting from the embedding process; instead the increased cross-sectional thickness of calendered samples is attributed to fibre rising.

Comparison of Abaca and Spruce as Reinforcement Fibre

Abstract: The effect of coarse abaca, fine abaca and spruce fibres on the fracture energy and fracture toughness of handsheets containing TMP is compared. The three fibres have very different lengths and coarsenesses. Damage width is used as a measure of the effective length of fibres. Damage width increases with increasing fibre length and decreases with increasing frequency of fibre failures. Damage width (effective fibre length) explains most of the observed variation in fracture energy and all the variation in fracture toughness of the three pulps. This may be because the pulps were beaten to give equal tensile strength for mixture sheets. Fibre coarseness affects the results primarily through fibre failures.

Effect of age on genetic control of Pinus radiata earlywood and latewood properties

Abstract: Narrow sense heritability (NSH), and parental breeding values (PBV), of density, tracheid (fibre) radial and tangential diameters and stem growth in a small 4 by 4 radiata pine diallel were studied as a function of age using SilviScan-1 (a combined scanning X-ray densitometer and automated image analysis system). The earlywood / latewood boundary was set at a density of 500 kg m -3 . Earlywood properties were moderately to strongly inherited (NSH = 0.3 to 0.6) from a young age and latewood properties, other than tangential tracheid diameter, were more weakly inherited (NSH = 0 to 0.6). We suggest that earlywood properties can be selected early in radiata pine and that physicomechanical properties of the growth ring depend to a large extent on those of the earlywood in this species. Significance of the results is discussed with particular references to refining behaviour and to sawn timber properties.

Visualisation of printing ink vehicle on paper surfaces by a SEM technique

Abstract: The images of vehicle in offset ink printed on paper were observed using the backscattered electron (BE) method, one of the variations of scanning electron microscopy (SEM). The images can be first visualised by modification of unsaturated carbon bonds in the vehicle with osmium tetroxide. This technique allows the evaluation of the print pattern of vehicle separately from that of the pigment. The area ratio of the digitised half tone dot images from the BE to that from the usual optical method was greater than unity. This indicated that distribution of the vehicle on the paper was wider than that of the ink pigments. Behavior of the printing ink vehicle penetration after printing was assessed by comparing images obtained from the BE technique with those from the optical method.

Effect of site on within-tree variation of wood properties of eucalypts as determined by NIR spectroscopy and multivariate analysis

Abstract: The variation in wood properties of trees of Eucalyptus globulus and Eucalyptus nitens grown on a range of sites in Tasmania, Victoria and Western Australia was explored by analysing their near infrared (NIR) spectra using Principal Components Analysis (PCA) and Soft Independent Modelling of Class Analogy (SIMCA). Core orientation (east-west or north-south), variation around breast height and longitudinal variation were examined. PCA models were developed for each set of samples (classes), and the distance between the classes, in terms of standard deviations, were measured using SIMCA. Comparison of models developed from cores with different cardinal directions showed that the models were only a small distance apart (maximum 1.48) indicating that core direction had little influence. Comparison of cores from 6 heights ranging from 0.5 to 1.5 m (0.2 m intervals) had larger model-to-model distances (maximum = 3.21) than the cardinally oriented cores. No consistent pattern of variation was observed between the heights. Models developed using discs from several heights ranging from 0 to 70% of tree height (10% intervals) were compared. Several heights were found to have model-to-model distances greater than 3. E. nitens from a Gippsland site had the largest model-to-model distances (maximum = 28.10) while E. globulus from a Southern Tasmanian site had the smallest (maximum = 4.27). It was found that model-to-model distance tended to increase as height increased to a maximum at 60 or 70% height, particularly in E. nitens.

Comparison of techniques to measure the fibril angle

Abstract: The different techniques available for the measurement of fibril angle are reviewed. A number of comparative sets of data in the literature are evaluated for information on the overall accuracy of fibril angle measurements. Recently, several new techniques for the measurement of fibril angle, which take advantage of the optical sectioning power of a confocal microscope, have been published. These techniques are reviewed and the relative advantages and disadvantages of each technique are discussed. The cellulose polymer molecules in wood fibres are aligned in long, highly crystalline microfibrils wound helically around the lumen. The S2 layer of the fibre wall contains as much as 90% of the fibre mass, and therefore largely determines the fibre properties. The pitch of the helix in the S2 layer defines the microfibril angle. As the fibrils in the S2 layer are tightly packed and the S2 layer is itself surrounded by the S 1 and S3 layers and is not exposed, it is not possible to simply place a fibre under a microscope and measure the fibril angle from visual observation, except in a limited number of special cases (eg, softwood compression wood). There is a wide variation in the properties of fibres from different parts of a tree and between different species of trees. Theoretical and experimental work (1-3) have shown that while the elastic modulus and strength of fibres are approximately constant at very low fibril angles, they fall rapidly for fibril angles beyond 5 or 10°. At fibril angles of 40° and above the tensile strength is reduced to about a third (1) and the stiffness is reduced to about a fifth (2) compared to fibres with fibril angles between 0 and 10°. The fibril angle also strongly affects the mechanical and shrinkage (4) properties of wood. Despite the importance of the fibril angle as a variable, influencing wood, fibre and paper properties, it is a quantity that is relatively rarely measured.

Reinforcing potential of different eucalypt : softwood blends during separate and co-PFI mill refining

Abstract: The reinforcement potential and optical properties of three market kraft pulps, two of New Zealand origin and a benchmark northern hemisphere pulp from interior British Columbia, Canada, were evaluated and compared following supplementation with a eucalypt market kraft pulp and refining. Eucalypt : softwood blends were investigated in the proportions of 100:0, 90:10, 80:20, 50:50 and 0:100, as were the effects of separate and co-refining employing a PFI laboratory refiner. The influence of softwood fibre quality on handsheet property interrelationships decreased with increasing proportions of eucalypt fibre present in the blends. The tear - tensile relationships, or furnish reinforcement strength, of 80:20 eucalypt : softwood blends were roughly the same and independent of the origin or type of softwood fibres used. It was apparent that the tear - tensile strength relationships were generally the same for PFI mill separate and co-refined eucalypt : radiata pine softwood blends in all proportions, while the eucalypt : McKenzie blends tended to develop lower tear strengths for given tensile strengths with PFI mill co-refining. In contrast, handsheet optical properties of all eucalypt : softwood blends demonstrated similar trends, regardless of the refining regime.

Effect of pH on kinetics and bleaching efficiency of chlorine dioxide delignification

Abstract: The pH has a pronounced effect on both kinetics and bleaching efficiency of chlorine dioxide delignification. Chlorine dioxide delignifies a Eucalyptus globulus kraft pulp at a faster rate, and more effectively, at pH 4 than at pH 2 or pH 10. The findings are consistent with previous suggestions that the kinetics and stoichiometry of chlorine dioxide delignification depend on the degree of conversion of chlorine dioxide into inactive chlorate and chlorite.

Surfactant based digester additive technology for kraft softwood and hardwood pulping

Abstract: A laboratory screening method, using an autoclave digester, has been developed for the evaluation of surfactants in kraft softwood and hardwood pulping. The effect of surfactants on cooking liquor penetration and diffusion has been explored. The use of surfactants results in a more uniform cook with lower Kappa numbers, lower screen rejects, lower pulp resin content, and improved black liquor residual active alkali content. The addition of 0.1% surfactant on o.d. wood resulted in a significant reduction of Kappa number with little loss of pulp yield. The resultant pulp yield at a constant Kappa number increased 0.5 to 1.0% over a conventional kraft cook. The laboratory results correlate very well with mill experience in screening additives for digester additive programs. Research proves that raising the Kappa number, with a surfactant, can boost wood yield. Kraft-surfactant pulping appears to be an appropriate technology in reducing screen rejects in combination with retrofitting oxygen delignification.

Effect of relaxation during drying on the final sheet properties

Abstract: Drying experiments were carried out with different drying powers to achieve a better understanding of the drying process and its effect on final sheet properties. The final sheet surface temperature and the rate of drying stress relaxation increased with the drying power. The trend of drying stress followed the interaction between an increase in the rate of drying stress relaxation and a decrease in drying time. When bleached kraft pulp (beaten and unbeaten) and TMP were compared, the beaten kraft pulp had the slowest rate of drying stress relaxation and the TMP the fastest rate. The mechanical properties of final sheets were quite independent of the drying power except for the strain at failure, which decreased with increasing drying power. The results show that there is not a general linear coupling between the drying stress and mechanical properties of paper.

Utilisation of additives in oxygen delignification of hardwood kraft pulp

Abstract: Oxygen delignification is widely applied in pulping and bleaching plants to meet stringent environmental regulations in different countries. The degree of oxygen delignification is often below 50%. One way to increase the delignification degree is to install capital-intensive two-stage, or multi-stage oxygen delignification systems. This study, however, selected the alternative of using additives to enhance the delignification degree. Surfactants, chelating agent DTPA(diethylenetriamine pentaacetate), peroxide bleaching activator TAED (tetraacetylethylene diamine), oxone (potassium peroxymonosulfate), KAQ (alkaline solution of disodium salt of 1,4-dihydro-9, 10-dihydroxy anthracene), AQ (anthraquinone) and urea were tested to assess their effects on the oxygen delignification of a hardwood kraft pulp. Whereas surfactants DTPA and TAED improved the delignification, KAQ and oxone decreased the delignification degree. AQ and urea, on the other hand, maintained the delignification degree. A mill trial using one of the surfactants (the non-ionic surfactant S) confirmed the laboratory results in terms of the gain in delignification degree and the preservation of pulp strength.

Genetics of heartwood formation and moisture status in Pinus radiata

Abstract: Genetic parameters of heartwood formation (Hf), detected using o-anisidine/ sodium nitrite, and moisture status (average content and content gradient) of a small 4 by 4 diallel progeny test of radiata pine involving parent 80055 were studied. Both properties exhibited a large phenotypic variation within families at 23 years of age. Parent 80055 developed heartwood to a greater extent than other parents (12038, 12197 and 12447), especially 12197. 80055 progeny were drier in the inner corewood (initial 6 growth rings) than progeny of other parents. This implies that wood of 80055 progeny may be more brittle during refining than that of other progeny. Strong positive phenotypic and genetic correlations were found between growth traits (section area at breast height, height, sapwood area, initial five year radial growth), Hf (rings and area) and moisture content gradient (Mcg) between the inner corewood and outer slabwood. Genetic control of heartwood formation traits was primarily through additive action of genes (GCA). Specific combining ability (SCA), reciprocal and maternal effects were absent, possibly due to the small sample size and a small number of reciprocal pairs. Additive genetic variance accounted for a third of total phenotypic variance in heartwood formation. The heritabilities of Hf and Mcg were high suggesting selection for traits was likely to be very effective.

Compression of paper in the z-direction : the effects of fibre morphology, wet pressing and refining

Abstract: The z-direction compression properties of paper have been shown to be dependent upon the morphological properties of pulp fibres. In particular, the cross-section dimensions of fibres greatly influence collapse behaviour of the fibres when dried, and hence greatly affect the final z-direction compressive properties of the sheet. Juvenile 6-year-old Eucalyptus regnans fibres were measured to have an average cell wall thickness approximately half that of 20-year-old E. globulus. Further, the percentage of collapsed fibres for unrefined E. regnans fibres measured in the dry state was significantly higher than for E. globulus. Confocal microscopy imaging of the sheet structure prior to, and after, loading some of the prepared samples allow qualitative observations of the effect of refining, wet pressing and z-direction compressive loads on the sheet structure. The images are consistent with observed compressive strain behaviour of the sheets.

Image analysis of plastic deformation in the fracture of paper

Abstract: A new imaging technique has been developed to characterise the outer plastic deformation field resulting from a fracture process in a sample of deep Double-Edge Notched Tension (DENT) geometry. This technique has the ability to measure strains of less than 0.1%. Commercial copy paper samples were used during the establishment of this technique. The results indicate that the plastic deformation field for fracture in the CD direction is more significant than that for fracture in the MD direction.

The alkaline digestion of reject fibre in deinking sludge as a precursor to filler recovery by wet air oxidation

Abstract: Waste deinking sludge produced in the recycling of paper comprises similar quantities of reject fibre and minerals (filler and coating) with very much smaller quantities of ink particles and organic polymeric material (stickies). The sludge is currently disposed of by land spreading, or by incineration and land filling the resulting ash. Both are environmentally undesirable and the valuable mineral components are lost. Hydrothermal oxidation at elevated temperature and pressure, using hydrogen peroxide, offers an attractive approach in removing the waste fibre, ink colorants and stickies. This yields the minerals as a free flowing white powder in an essentially unaltered form, which can potentially be re-used as a filler material. However, as the majority of the oxidant is consumed in oxidising the waste fibre an alternative two-stage process has been developed. In the first stage the fibre and stickies are removed by alkaline hydrothermal hydrolysis using 1 molar NaOH at 250°C for 2 hours, which yields an amber coloured solution and a grey solid. Chromatographic separation and analysis has shown that the solution contains mainly low molecular mass polar carboxylic acids, notably lactic and formic acid, as the most abundant followed by glycolic, 3,4-dideoxypentonic and 2-hydroxybutanoic acid, formed largely from the hydrolysis of the cellulose. There is also a non-polar component formed from the hydrolysis of lignin and stickies. The grey solid comprises mainly calcium carbonate and kaolinite coated with ink colorants. In the second stage this grey powder is subjected to hydrothermal oxidation also at 250°C for up to 2 hours using a very much reduced quantity of hydrogen peroxide. The ink colorants are removed to yield a free flowing white powder, which is a mix of the original filler and coating minerals. The physical and optical properties of this powder suggest it can be re-used as filler in newsprint and similar paper grades.

Characterisation of transition metal removal from mechanical pulps by chelating with DTPA in a displacement system

Abstract: Chelation in a displacement system (displacement chelation) is an effective way to remove transition metal ions from pulp fibres. The breakthrough curves of manganese removal were studied as functions of process variables: temperature, superficial velocity and DTPA concentration. It was found that these three parameters did not affect the manganese breakthrough curves. These results are explained by the hypothesis that the displacement chelation process is neither a kinetic nor diffusion controlled process, and that it is governed by the flow characteristics of the pulp pad.

Preliminary development of a laboratory former for oriented sheets

Abstract: The production of paper in the laboratory, where controlled forming conditions result in an anisotropic sheet of predictable properties that match those of papers made on commercial paper machines, is a long desired instrument for many researchers. A laboratory sheet former based on a novel interpretation of the flow in the forming region is being developed to meet this challenge. The key sheet characteristics, for a given fibre stock, were identified to be formation and fibre orientation. The ability of this laboratory former to simulate commercial paper was assessed by a number of standard tests. The sheets formed on the initial prototype (Mk I) confirmed that the conceptual design was worth pursuing, and that improvements to the control and operation were required. The design improvements made to the laboratory former resulted in a second device (Mk II), which produced oriented sheets in a repeatable manner with sheet characteristics comparable to commercially made paper. The practical difficulties encountered in the development of this device are discussed along with the solutions that were found.

Bleaching of maple CTMP pulp to high brightness using the PN2 process

Abstract: A new process has been developed for the bleaching of mechanical and ultra high yield pulps to enhanced brightness levels with alkaline hydrogen peroxide. In this process mechanical pulp bleaching is performed in an inert atmosphere, for example, in the presence of nitrogen. Compared with conventional peroxide bleaching, such a process can produce bleached mechanical pulps with higher brightness at a given hydrogen peroxide charge/consumption.

Association of fibre morphology with cambial age and attained height : new oblique axes for whole tree variation in Eucalyptus globulus

Abstract: Fibres of a specific morphology are formed by cambia of the same or similar age at systematic and consistent partitions of the whole tree; following an oblique directionality from pith to bark and up the stem. Whole tree variation of eight fibre dimensions - fibre length, fibre diameter, lumen diameter and fibre wall thickness and 4 derived wood quality indices; fibre coarseness (CR), Runkel ratio (RR), wall coverage ratio (WCR) and Muhlsteph ratio (MR) are shown to be strongly associated (P>0.000 01) with cambial age (CA) at year of production; and (i) change with growth rings from pith to bark (increasing CA) and (ii) vary directly (P <0.000 01) with CA (decreasing up stem) within each ring. Within ring height partitions (based on varying CA) which are translatable to whole tree height partitions (based on varying CA) and between which fibre morphology varies significantly (P <0.0001) are shown for E. globulus.