Development of fibre properties in mill scale high- and low consistency refining of thermomechanical pulp (Part 1)

The aim of this study was to evaluate changes in fibre properties with high (HC)- and low consistency (LC) refining of TMP and determine how these contribute to tensile index. Two process configurations, one with only HC refining and another with HC refining followed by LC refining were evaluated in three TMP mainline processes in two mills using Norway spruce. An increase in tensile index for a given applied specific energy was similar for all LC refiners in the three lines, despite differences in the fibre property profiles of the feed pulps. Compared with only HC refined pulps at a given tensile index, HC+LC refined pulps had greater fibre wall thickness, similar fibre length, strain at break and freeness, but lower light scattering coefficient, fibre curl and external fibrillation. The degree of internal fibrillation, determined by Simons’ stain measurements, was similar for both configurations at a given tensile index. The results indicate that the increase in tensile index in LC refining is largely influenced by a decrease in fibre curl and in HC refining by peeling of the fibre walls. Compared at a given tensile index, the shive content (Somerville mass fraction) was similar for both HC+LC and HC refining.

Regressional Estimation of Cotton Sirospun Yarn Properties from Fibre Properties

In this paper, it is aimed at determining the equations and models for estimating the sirospun yarn quality characteristics from the yarn production parameters and cotton fibre properties, which are focused on fibre bundle measurements represented by HVI (high volume instrument). For this purpose, a total of 270 sirospun yarn samples were produced on the same ring spinning machine under the same conditions at Ege University, by using 11 different cotton blends and three different strand spacing settings, in four different yarn counts and in three different twist coefficients. The sirospun yarn and cotton fibre property interactions were investigated by correlation analysis. For the prediction of yarn quality characteristics, multivariate linear regression methods were performed. As a result of the study, equations were generated for the prediction of yarn tenacity, breaking elongation, unevenness and hairiness by using fibre and yarn properties. After the goodness of fit statistics, very large determination coefficients (R2 and adjusted R2) were observed.

Prediction of Tensile Properties of Injection Moulding Flax Fibre Reinforced Polypropylene from Morphology Analysis

The Young modulus and tensile strength of flax fibre reinforced polypropylene were determined and compared with the micromechanical models usually used in the case of short glass fibre reinforced composites. The fibre length and fibre diameter distributions of the injected reinforced of 2, 4, 8 and 22vol% compound were determined and used to the models in order to evaluate the expected properties of the composites. The mechanical properties were interpreted on the base of real fibre content, fibre orientation, fibre length and diameter distributions and morphology of the composites. The Kelly-Tyson’s model of the tensile strength prediction has been modified to take in consideration the fibre property variability due to the large distribution of fibre shape ratio induced by the process. Finally matrix modulus has been adjusted to take into account the change of crystallinity with fibre content.

Vessel and Fibre Property Variation in Eucalyptus Globulus and Eucalyptus Nitens: Some Preliminary Results

Vessel areas and distributions in Eucalyptus globulus and E. nitens vary in a consistent, significant and predictable way from pith to bark and within annual rings. Trends in vessel areas and distributions can be quantified despite the presence of indistinct annual rings and false rings. There is evidence of a vessel free area in first earlywood in E. nitens in which fibre properties are predictably different. At 5% height the vessel free area in the 1991 and 1992 annual rings is 13% and 1O% respectively.

Studies to Measure Cotton Fibre Length, Strength, Micronaire and Colour by vis/NIR Reflectance Spectroscopy. Part II: Principal Components Regression

In Part I of this series, both cotton fibre property and reflectance spectra data on 185 US cottons including four Pimas were analysed by descriptive statistics. In this paper, principal components regression (PCR) models for measuring six properties from the cotton's vis/NIR reflectance spectra are critically examined. These properties are upper-half mean length (UHM), uniformity index (UI), bundle strength (STR), micronaire (MIC) and colour (Rd and +b). The spectra were recorded with a scanning spectrophotometer in the wavelength range from 400 to 2498 nm. A variety of spectral processing options, some of which give improved PCR analysis results, were applied prior to the regressions and allowed for testing of over 100 PCR models. All PCR model results are based on the PRESS statistic by one-out-rotation, a fast approximation of the PRESS statistic (to reduce computer time) or on cluster analysis using separate calibration and validation data sets. The standard error of prediction (SEP) of all the properties except UHM compared well to the reference method precision. The precision of the UHM measure by reflectance spectroscopy was strongly influenced by the sample repack error. The SEP of UHM, UI and STR was improved by excluding the Pimas from the data set.

Studies to Measure Cotton Fibre Length, Strength, Micronaire and Colour by Vis/NIR Reflectance Spectroscopy. Part I: Descriptive Statistics of Fibre Properties and Reflectance Spectra

Fibre property data representing the 1989 and 1990 crop years and its reflectance spectra are analysed using standard error, regression and correlation analysis. The six properties of interest are upper-half mean length, uniformity index, strength and micronaire measured on two high volume instrument systems placed side-by-side, and colour (Rd and +b) measured by the traditional lab system. Visible (vis) and near infrared (NIR) reflectance spectra are observed on a scanning spectrophotometer, and span the 400–2500 nm range. Three findings highlight the research. One, a diagnostic test is presented to decide, a priori of reflectance spectroscopy, the degree to which the mean property values have reduced random error. Two, the standard error of replicate spectra provides a way to probe the fibre mass in the diffuse reflectance optical path. The spectral error is strongly influenced by both how the cotton is packed into the spectrophotometric cell and the non-homogeneity of the sample. And three, correlations between the spectra confirm that some visible and NIR wavelength regions contain mutually exclusive information about the properties of this natural staple.

Response of Egyptian cotton (Gossypium barbadense) yield to 1,1-dimethyl piperidinium chloride (Pix)

SUMMARYTwo field experiments were conducted in Egypt in 1985 and 1986 to examine the responses of yield and its components and fibre quality in the Egyptian cotton cultivar Giza 75 to the spray application of 0, 10, 20, 40, 60, 80, and 100 mg of 1,1-dimethyl piperidinium chloride (Pix)/litre at 90 days or at 90 and 110 days after sowing. Number of opened bolls/plant, boll weight, seed and lint index, seed cotton yield/plant, seed cotton and lint yield/ha and yield earliness increased, but lint percentage decreased after Pix application. The number of opened bolls/plant increased after one application, but there was no effect from a further application. There were no effects of concentration or number of applications of Pix on any fibre property.