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Paper surface diffraction to characterise the fibre orientation distribution

Pereira, M.J.T.; Fiadeiro, P.T.; Silvy, J.

Many paper mills use ultrasonic techniques to measure the Tensile Stiffness Index, TSI, of the paper sheet. They then assume that the TSI value is the same as the fibre orientation anisotropy. This is true if the paper is allowed to dry without any internal tension or elongation, but does not apply to paper manufactured in a paper machine. The paper machine introduces tension and elongation as soon as the fibre...

Data: 2010   |   Origem: Ubi Thesis - Conhecimento Online

Diffusion of the Laser Radiation to Characterise the Paper Fibre Orientation an...

PEREIRA, M.J.T.; P.T.Fiadeiro; F.M.P.B.Ferreira

This work concerns the determination of fiber orientation in the paper sheet and possibly the mass density distribution. Both parameters strongly influence the quality of the paper for end uses in printing and converting. The measurement of such parameters is done using different approaches, most commonly indirectly from the determination of the paper's physical properties. The measurement and analysis of ...

Data: 2010   |   Origem: Ubi Thesis - Conhecimento Online

The Surface Measurement of Fibre Orientation Anisotropy and Misalignment Angle ...

Pereira, M.J.T.; Fiadeiro, P.T.; Jesus, M.E.P.; Silvy, J. J.

The dimensional stability in fibre webs mainly depends of the fibre anisotropy and its orientation on the surfaces. These parameters are influenced during the manufacturing process, where the length and type of the fibres is determinant. The web quality control, in general, is performed based on the measurement of these parameters in the bulk of the fibre webs. This paper presents an optical laser diffraction m...

Data: 2010   |   Origem: Ubi Thesis - Conhecimento Online

O índice e a direcção de rigidez na quantificação da orientação das fibras no p...

PEREIRA, M.J.T.; P.T. Fiadeiro

As técnicas ultra-sónicas encontram-se amplamente divulgadas na indústria do papel para medição do índice de rigidez (TSI) das folhas de papel. Para a indústria do papel o valor deste índice é assumido como sendo igual à anisotropia de orientação das fibras, o que acontece só quando a folha de papel é seca sem estar sujeita a tensões internas ou elongações. De forma a medir unicamente a anisotropia de orientaçã...

Data: 2010   |   Origem: Ubi Thesis - Conhecimento Online

3-D Characterisation of Nonwoven Fabrics by means of an optical system

PEREIRA, M.J.T.; L. R. Salvado; P. T. Fiadeiro; J. Silvy

The characterisation of fabric structure by means of quantified parameters is essential for the control of the fabrication processes and the resulting properties of the nonwoven materials. Important parameters of the structure are the porosity, the mean pore size and the pore size distribution, the specific area of the texture, the fibres orientation the last one needing to be characterised in the three dimensi...

Data: 2010   |   Origem: Ubi Thesis - Conhecimento Online

New method for the measurement of fibres orientation on the paper faces applied...

Pereira, M.J.T.; Costa, A.P.; Trindade, A.C.; Fiadeiro, P. T.; Silvy, J.; Tosio, J.M.Serra

For a given change in the humidity of a paper the hygro-instability of the sheet depends of two main factors:  the sheet structural parameters which reflects its structure: the sheet porosity, the fibres orientation distribution mainly in the sheet plane and the variations of these parameters across the paper sheet thickness.  the water reactivity of the components of the paper sheet which depends mainly of t...

Data: 2010   |   Origem: Ubi Thesis - Conhecimento Online

Structure of papers and Nonwovens

PEREIRA, M.J.T.; A.P. Costa; R. Salvado; J. Silvy; P.T. Fiadeiro

We characterise the structure of fibrous materials: papers and nonwovens by diffraction and transmission of light. This allows the measurement of the fibres orientation distribution of the sample as a whole or for the surfaces using replicas. Applications of the methods are demonstrated in the case of paper for the control of the curl tendency and for two kinds of nonwoven materials, one used in the tailoring o...

Data: 2010   |   Origem: Ubi Thesis - Conhecimento Online

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Fundação para a Ciência e a Tecnologia Universidade do Minho   Governo Português Ministério da Educação e Ciência Programa Operacional da Sociedade do Conhecimento União Europeia