ISO 16065-1:2014

INTERNATIONAL ISO
STANDARD 16065-1
Second edition
2014-04-01
Pulps — Determination of fibre length
by automated optical analysis —
Part 1:
Polarized light method
Pâtes — Détermination de la longueur de fibre par analyse optique
automatisée —
Partie 1: Méthode de la lumière polarisée
Reference number
©
ISO 2014
© ISO 2014
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Published in Switzerland
ii © ISO 2014 – All rights reserved

Contents Page
Foreword .iv
1  Scope . 1
2  Normative references . 1
3  Terms and definitions . 1
4  Principle . 2
5  Apparatus and materials. 2
6  Sampling and preparation of sample . 4
6.1 Sampling . 4
6.2 Disintegration . 4
6.3 Stock dilution. 4
7  Measurement and verification procedures . 4
7.1 Measurement procedure . 4
7.2 Verification procedure . 5
8  Calculation and expression of results . 5
8.1 Method of calculation . 5
8.2 Characteristic distribution values . 6
9 Test report . 7
Annex A (informative) Precision . 8
Bibliography .10
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 6, Paper, board and pulps.
This second edition cancels and replaces the first edition (ISO 16065-1:2001), of which it constitutes a
minor revision with the following changes:
— a new precision statement that complies with the requirements of ISO/TR 24498 has been added.
ISO 16065 consists of the following parts, under the general title Pulps — Determination of fibre length
by automated optical analysis:
— Part 1: Polarized light method
— Part 2: Unpolarized light method
iv © ISO 2014 – All rights reserved

INTERNATIONAL STANDARD ISO 16065-1:2014(E)
Pulps — Determination of fibre length by automated
optical analysis —
Part 1:
Polarized light method
1  Scope
This part of ISO 16065 specifies a method for determining fibre length using polarized light.
This part of ISO 16065 is applicable to all kinds of pulp. However, fibrous particles shorter than 0,2 mm
are not regarded as fibres for the purposes of this part of ISO 16065 and, therefore, are not to be included
in the results.
NOTE ISO 16065-2 deals with the determination of fibre length using unpolarized light.
2  Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 638, Paper, board and pulps — Determination of dry matter content — Oven-drying method
ISO 4119, Pulps — Determination of stock concentration
ISO 5263-1, Pulps — Laboratory wet disintegration — Part 1: Disintegration of chemical pulps
ISO 5263-2, Pulps — Laboratory wet disintegration — Part 2: Disintegration of mechanical pulps at 20
degrees C
ISO 5263-3, Pulps — Laboratory wet disintegration — Part 3: Disintegration of mechanical pulps at > 85
degrees C
ISO 7213, Pulps — Sampling for testing
ISO/TR 24498, Paper, board and pulps — Estimation of uncertainty for test methods
3  Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
unpolarized light
light composed of light waves whose planes of vibration are randomly oriented
3.2
polarizer
material which only transmits a component of a light wave which is vibrating in a particular direction,
which is the direction of polarization of the material
3.3
plane polarized light
light composed of light waves which all vibrate in the same plane
3.4
crossed polarizers
pair of polarizers placed in a light path, such that the direction of polarization of one is at right angles to
the direction of polarization of the other, thus resulting, ideally, in none of the light, which has passed
directly from one polarizer to the other, being transmitted
3.5
birefringence
property of certain materials, such as cellulose fibres, which have a crystalline
structure that results in the refractive index varying with the direction of polarization of the light
Note 1 to entry: This has the effect of rotating the direction of polarization of a plain polarized beam of light
resulting in light which has passed through this material being transmitted through the second polarizer of a
crossed pair.
3.6
mean length
L
total length of all fibres counted divided by the number of fibres
Note 1 to entry: See Formula (3).
3.7
length-weighted mean length
L
l
average of the length-weighted fibre-length distribution
Note 1 to entry: See Formula (4).
3.8
mass-weighted mean length
L
w
average of the mass-weighted fibre-length distribution
Note 1 to entry: See Formula (5).
Note 2 to entry: Mass-weighted mean length was formerly called weight-weighted mean length.
3.9
light extinction
difference, expressed as a percentage, in the maximum and minimum light level transmitted through
two axially aligned polarizers when one polarizer is rotated 90° about the axis
4  Principle
Fibres suspended in water are routed through a fibre orienting cell (FOC). The projected lengths of
individual fibres are measured automatically. A crossed-polarizers setup is used to discriminate
between fibres and other materials like air bubbles, which do not rotate the plane of polarization. The
numerical and weighted average fibre lengths and fibre-length distributions of pulp are calculated.
5  Apparatus and materials
Ordinary laboratory equipment and the following are required.
5.1 Fibre-length analyser, consisting of a measurement section and a sample transport system (see
Figure 1).
The measurement section consists of a fibre orienting cell (FOC), through which fibres in a liquid are
drawn. There is a uniform light source on one side of the FOC and a photo sensor matrix on the opposite
2 © ISO 2014 – All rights reserved

side. There are crossed polarizing filters, on either side of the FOC, between the light source and the
photo sensor matrix. The photo sensor matrix senses the length of the image of the fibre from the light
that due to the birefringence is transmitted through the second polarizer. The length of this image is
converted to fibre length. The flow orientates the fibres into a plane or tube normal to the light path and
no thicker than 0,5 mm in the direction of the light path. The resolution of the analyser shall be equal to
or better than 100 µm over the range 0 mm to 7 mm.
NOTE Fibres constrained to flow through a capillary no wider than 0,5 mm have been found to straighten
enough to be measured accurately with projected light.
At least 90 % of the transmitted light spectrum shall be within the spectral sensitivity of the detector.
The light extinction of the crossed polarizers shall exceed 99 %. The detection efficiency shall be 100 %
for all fibres 0,100 mm and longer.
Key
1 light source
2 FOC
3 photo sensor
4 polarizing optics
Figure 1 — An example of the measurement principle
5.2 Disintegrator, as described in ISO 5263.
5.3 Pipette, having a volume of 50 ml ± 0,5 ml, with a tip opening of at least 5 mm for sampling a
50 ml test portion.
5.4 Verification fibres, made of rayon or other suitable material, with suggested lengths of about
0,5 mm, 3,0 mm, and 7,0 mm.
The fibres shall be provided by the producer of the analyser, together with statistical data showing the
mean length and the length distribution of each type of verification fibre.
1)
5.5 Reference pulp .
1) Reference pulp is available, for example, from the National Institute of Science & Technology, Gaithersburg,
MD, USA (NIST). The reference pulp is provided in sheet form. This information is given for the convenience of users
of this document and does not constitute an endorsement by ISO of the product named.
6  Sampling and preparation of sample
6.1  Sampling
If the test is being made to evaluate a pulp lot, the sample shall be selected in accordance with ISO 7213. If
the test is made on another type of sample, report the source of the sample and, if possible, the sampling
procedure used.
From the sample received, select specimens so that they are representative of the whole sample.
6.2  Disintegration
If the sample is in dried form, determine the dry matter content in accordance with ISO 638. If the
sample is in slush form, determine the stock concentration in accordance with ISO 4119.
NOTE It is preferable to measure never-dried pulps without disintegration because excessive disintegration
can generate fines and reduce fibre length in some pulps.
If the sample is in dried form, tear the specimens into pieces before soaking. Tear the pieces evenly
through
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