Iec 60811 4 1 2004

INTERNATIONALE IECINTERNATIONAL STANDARD 60811-4-1 Deuxième éditionSecond edition2004-06 Matériaux d'isolation et de gainage des câbles électriques et optiques – Méthodes d'essais commu

Domaine d'application

This section of IEC 60811 outlines the testing methods for polymer insulation and sheathing materials used in electrical and optical cables for energy distribution and telecommunications, including those on ships and for offshore applications These testing methods specifically apply to polymer blends.

PE et PP, y compris les mélanges d’isolation cellulaire avec ou sans peau.

Généralités

Ces procédures d'essais s'appliquent uniquement aux granulés d'origine utilisés comme matériaux de gainage

S'applique aux matériaux soumis à des conditions et à des environnements moins sévères pour le système câblé

S'applique aux matériaux soumis à des conditions et à des environnements plus sévères pour le système câblé

LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU.

This standard does not specify full test conditions, including temperatures and durations Instead, it is intended that these details be outlined by the standard applicable to the specific type of cable.

Any test requirements which are given in this standard may be modified by the relevant cable standard to suit the needs of a particular type of cable

Conditioning values and testing parameters are specified for the most common types of insulating and sheathing compounds and of cables, wires and cords

5 Type tests and other tests

The test methods described in this standard are primarily intended to be used for type tests

In certain tests, where there are essential differences between the conditions for type tests and those for more frequent tests, such as routine tests, these differences are indicated

All the tests shall be carried out not less than 16 h after the extrusion or vulcanization (or cross-linking), if any, of the insulating or sheathing compounds

The median value is determined by arranging test results in ascending or descending order If there is an odd number of values, the median is the middle value Conversely, if the number of values is even, the median is calculated as the average of the two middle values.

8 Resistance to environmental stress cracking

These test procedures apply only to the original granules used as sheathing materials

Applies to materials which will encounter less severe cable system conditions and environ- ments

Applies to materials which will encounter more severe cable system conditions and environ- ments

Appareillage

L’appareillage doit comporter les éléments suivants:

8.2.1 Presse chauffante pour fabriquer les plaques d'essai moulées, munie de plateaux plus larges que les plaques d'appui

8.2.2 Deux plaques d'appui en métal rigide de (6 ± 0,5) mm d'épaisseur et d'environ

Each plate measures 200 mm by 230 mm and features a hole on one side, allowing a temperature indicator to be positioned 5 mm from the center of the plate.

8.2.3 Deux feuilles intercalaires d'environ 200 mm × 230 mm, par exemple des feuilles en aluminium de 0,1 mm à 0,2 mm d'épaisseur

8.2.4 Des châssis de moulage prévus pour réaliser des plaques d'essai 150 mm x 180 mm x

(3,3 ± 0,1) mm comportant un angle intérieur arrondi sur un rayon de 3 mm

8.2.5 Une étuve à air chauffée électriquement avec circulation d'air forcée et un dispositif de programmation permettant d'abaisser la température à une vitesse de (5 ± 0,5) K/h

8.2.6 Un emporte-pièce, propre, affûté, sans défaut, ainsi qu'une presse permettant de découper des éprouvettes de (38,0 ± 2,5) mm × (13,0 ± 0,8) mm ou tout autre dispositif adéquat

8.2.7 Un micromètre à cadran à touches planes de 4 mm à 8 mm de diamètre et à jauge de pression de 5 N/cm 2 à 8 N/cm 2

8.2.8 Appareil à entailler (voir Figure 1), muni de lames (voir Figure 2)

NOTE La lame est profilộe à partir de lames ôGemằ selon la Figure 2; voir ộgalement l’Annexe A

The apparatus shall comprise the following elements:

8.2.1 Heatable press for producing moulded test sheets, with platens which are larger than the backing plates

Two rigid metal backing plates, each measuring approximately 200 mm × 230 mm and having a thickness of 6 ± 0.5 mm, are designed with a drilled hole near one edge to accommodate a temperature sensor positioned within 5 mm of the plate's center.

8.2.3 Two separator sheets, about 200 mm × 230 mm, for instance aluminium foil 0,1 mm to 0,2 mm thick

8.2.4 Suitable moulding chases for producing test sheets, 150 mm × 180 mm ×

(3,3 ± 0,1) mm with internal corners rounded to a radius of 3 mm

8.2.5 Electrically heated air oven with forced air circulation and programming device which lowers temperature at a rate of (5 ± 0,5) K/h

8.2.6 Clean, sharp, undamaged blanking die with blanking press suitable for cutting test pieces (38,0 ± 2,5) mm × (13,0 ± 0,8) mm or other suitable devices

8.2.7 Dial gauge, with plane gauging faces 4 mm to 8 mm in diameter and a gauging pressure of 5 N/cm 2 to 8 N/cm 2

8.2.8 Notching devices as in Figure 1 with blades as in Figure 2

NOTE The blade is made of “Gem” blades as in Figure 2 – see also Annex A

8.2.9 Presse de pliage (voir Figure 3) comprenant un étau ou tout autre dispositif permettant d'obtenir la fermeture symétrique des mâchoires de serrage

8.2.9 Bending clamp assembly as in Figure 3 with vice or other suitable device ensuring the symmetrical closing of the clamping jaws

8.2.10 Outil de transfert (voir Figure 4) permettant de déplacer en une seule fois les éprouvettes d'essais pliées de la presse de pliage au support en laiton

8.2.11 Support d'échantillon en laiton (voir Figure 5) en forme de gouttière permettant de réunir dix éprouvettes pliées

La dimension de 11,75 mm ± 0,05 mm est la largeur interne du support

Figure 5 – Support d'échantillon en laiton

The 200 mm × 32 mm tempered glass test tubes are designed to accommodate brass sample holders and bent samples These tubes are sealed with caps wrapped in suitable aluminum foil (see Figure 6).

8.2.10 Transfer tool assembly as in Figure 4 for shifting in one operation the bent test piece(s) from the bending clamp to the brass channel

8.2.11 Brass channel specimen holder as in Figure 5 for accommodating ten bent test pieces

The dimension 11,75 mm ± 0,05 mm is the channel internal width

Figure 5 – Brass channel specimen holder

Hard glass test tubes measuring 200 mm × 32 mm are designed to hold the brass channel specimen holder along with bent test specimens These tubes are sealed with appropriate aluminum foil-wrapped corks for optimal containment.

Figure 6 – Tube à essai contenant le support d'éprouvettes en laiton (voir 8.2.11) sur lequel sont maintenues dix éprouvettes 8.2.13 Réactifs

Igepal CO-630 à 100 % (Antarox CO-630) ou tout autre réactif ayant la même composition chimique (voir Notes 1 et 2 ci-dessous et l’Annexe A)

Solution à 10 % en volume d'Igepal CO-630 (Antarox CO-630) dans l'eau ou tout autre réactif ayant la même composition chimique (voir Notes 1, 2 et 3 ci-dessous et Annexe A)

NOTE 1 Il convient que le réactif ne soit pas utilisé plus d'une fois

If the cracking time is shorter than expected, it is essential to check the moisture content of the reagent, as a slight increase in moisture beyond the specified value of 1% could lead to a significant rise in the reagent's activity.

It is essential to prepare the Igepal CO-630 solution or a similar product by stirring the mixture at a temperature between 60 °C and 70 °C for at least one hour The solution should be used within one week of preparation.

A heated container, with adequate dimensions and depth to hold the supports for the filled test tubes (see Figure 6), must maintain a temperature of (50 ± 0.5) °C using appropriate equipment The thermal capacity should be sufficiently high to ensure that the temperature never drops below 49 °C, even when the test tubes are submerged.

Figure 6 – Test tube with inserted brass channel specimen holder as in 8.2.11, containing ten test specimens 8.2.13 Reagents

100 % Igepal CO-630 (Antarox CO-630) or any other reagent having the same chemical composition (see Notes 1 and 2 below and Annex A)

10 % solution (by volume) in water of Igepal CO-630 (Antarox CO-630) or any other reagent having the same chemical composition (see Notes 1, 2 and 3 below and Annex A)

NOTE 1 The reagent should not be used more than once

In cases of unexpectedly short failure times, it is essential to verify the water content of the reagent, as even minor increases beyond the maximum limit of 1% can lead to a substantial rise in reagent activity.

Prepare a water solution of Igepal CO-630 or a similar material by paddle-stirring the mixture at a temperature of 60 °C to 70 °C for a minimum of one hour It is essential to use the solution within one week of its preparation for optimal effectiveness.

A heated container must be adequately sized and deep enough to accommodate racks for filled test tubes, as illustrated in Figure 6 The temperature within the container should be consistently maintained at (50 ± 0.5) °C using appropriate equipment, ensuring that the thermal capacity is sufficient to prevent the temperature from falling below 49 °C, even when test tubes are added.

Préparation des plaques d'essai

To prepare the test plates, a clean interleaving sheet as per section 8.2.3 must be placed on the support plate according to section 8.2.2, with the molding frame conforming to section 8.2.4 The frame should be filled with (90 ± 1) g of pellets or ground product to create a continuous layer, followed by a second interleaving sheet and then the second support plate No release agent should be used.

8.3.2 Cet ensemble doit être placé dans la presse chauffante décrite en 8.2.1, chauffée au préalable à 170 °C Une force ≤1 kN est appliquée par fermeture des plateaux

When the temperature measured by the sensors in the support plates reaches between 165 °C and 170 °C, apply the full load of 50 kN to 200 kN to the mold using the press for a duration of 2 minutes, during which the sensors must continue to indicate a temperature within the same range After the pressing phase, heating should be halted by either removing the mold from the press or rapidly cooling the press while maintaining full force.

Conditionnement des plaques d'essai

The outcome of the trial may depend on the conditioning, which will be mutually agreed upon by the interested parties In the absence of such an agreement, the treatment described herein shall serve as the reference treatment.

Support plates are removed without damaging the spacers The molded test plate is then placed in the oven specified in section 8.2.5, ensuring that air circulates freely around it The molding must be applied horizontally on the conductive surfaces to maintain good contact between the spacers and the polyethylene.

La température à une distance inférieure à 5 mm au-dessus du centre de la surface horizontale de la plaque moulée doit ensuite être contrôlée comme suit

The oven temperature must be maintained for 1 hour at 145 °C ± 2 °C for low-density polyethylene, 155 °C ± 2 °C for medium-density polyethylene, and 165 °C ± 2 °C for high-density polyethylene Cooling should occur at a specific rate.

The cooling rate should be maintained at (5 ± 2) K/h until the temperature reaches 29 °C ± 1 °C It is also permissible to cool the molded plates within the press itself The actual cooling speed must be recorded on a graph.

NOTE Le conditionnement des plaques est facultatif En cas de doute, il convient d'utiliser une éprouvette conditionnée.

Examen visuel des plaquettes d'essai

Les plaques doivent normalement présenter une surface lisse et ne contenir ni bulles ni empreintes superficielles à moins qu'elles ne soient situées dans les 10 mm à partir des bords.

Méthode d'essai

Using the punch and die press described in section 8.2.6 or another suitable tool, cut ten specimens as indicated in section 8.6.2 from the plate, ensuring that they are positioned 25 mm from the edges This method preserves the integrity of the material film located between the holes after the specimens are extracted, preventing damage during handling.

The thickness of the specimens, measured using a dial micrometer as per section 8.2.7, must comply with section 8.6.2 The edges of the specimen should be square; any deviations can lead to inaccurate results.

8.3 Preparation of the test sheets

To prepare a test, place a clean separator foil on the backing plate, followed by the moulding chase Fill the chase with (90 ± 1) g of granules or mill-massed material to create a uniform layer Then, add a second separator foil and a second backing plate on top, ensuring that no release agent is used.

8.3.2 The mould assembly shall be placed in the moulding press as in 8.2.1, preheated to 170 °C, and the press shall be closed, using a force ≤1 kN

8.3.3 When the temperature, as indicated by the sensors in the backing plate, has reached

At temperatures between 165 °C and 170 °C, a force ranging from 50 kN to 200 kN must be applied to the mould using a press for 2 minutes, while sensors maintain the specified temperature range After this phase, the heating of the mould assembly can be halted by either removing it from the press or by implementing fast cooling while still under full force.

8.4 Conditioning of the test sheets

The conditioning of test sheets must be mutually agreed upon by the involved parties, as it can significantly influence the test outcomes In the absence of such an agreement, the procedures outlined in this subclause will serve as the standard reference treatment.

After carefully removing the backing plates while keeping the separator foil intact, the moulded test sheet should be positioned in an oven to allow for adequate air circulation It is essential that the moulding is securely supported on thermally conductive horizontal surfaces, ensuring optimal contact between the separator foils and the polyethylene.

The temperature as measured not further than 5 mm above the centre of the horizontal surface of the moulded sheet shall then be controlled as follows:

The oven test requires maintaining specific temperatures for one hour: 145 °C ± 2 °C for low-density polyethylene, 155 °C ± 2 °C for medium-density polyethylene, and 165 °C ± 2 °C for high-density polyethylene Cooling should occur at a rate of (5 ± 2) K/h until the temperature reaches 29 °C ± 1 °C, and it is acceptable to cool the molded test sheets while still in the press The actual cooling rate must be documented using a graphical recorder.

NOTE Conditioning of the test sheets should be optional In case of dispute, a conditioned specimen should be used

8.5 Visual examination of the test sheets

The sheet shall exhibit a smooth surface and shall not contain any bubbles, lumps or sink marks except within 10 mm of the edge

8.6.1 Preparation of the test pieces

To ensure proper handling and avoid damage, ten test pieces must be cut from a test sheet using a blanking die and blanking press, or other appropriate devices, ensuring they are located more than 25 mm from the sheet's edges.

The thickness of the test pieces, measured with a dial gauge as specified in section 8.2.7, must comply with section 8.6.2 It is essential that the test pieces are cut with square edges, as beveled edges can result in inaccurate measurements.

8.6.2 Entaille et disposition des éprouvettes

Peu de temps avant d'être immergée dans le réactif, chaque éprouvette doit être entaillée (voir

When using the 8.2.8 notching device, ensure that the blade is neither dull nor damaged, and replace it if necessary Even under optimal operating conditions, it is advisable not to exceed 100 notches.

Densité des polyéthylènes de gainage a

0,50 à 0,65 0,30 à 0,40 a La densité est celle de la résine non chargée, selon l’Article 4 b La profondeur D doit être uniforme sur toute sa longueur

The ten test tubes are placed in the bending press with the notch facing upwards The jaw must be closed using a clamp or a motorized press at a constant speed for a duration of 30 to 35 seconds.

Bent test specimens are removed from the bending jaw using the transfer tool 8.2.10 and placed into the brass trough 8.2.11 If some specimens are positioned too high compared to the others, they must be leveled manually by applying pressure.

The support should be placed in a tube according to section 8.2.12, 5 to 10 minutes after the samples have been folded The test tube must be filled with the appropriate reagent as specified.

8.2.13 jusqu'à ce que toutes les éprouvettes soient recouvertes par le liquide, et il doit être obturé avec un bouchon

Le tube est placé immédiatement dans un râtelier à l'intérieur du récipient chauffé selon

8.2.14 Veiller à ce que les éprouvettes ne touchent pas le tube pendant l'essai Noter le moment à partir duquel les tubes sont immergés dans le récipient chauffé

8.6.2 Notching and inserting of the test pieces

Shortly before placing into the reagent, each of the test pieces shall be given a notch (see

The notching device, as illustrated in Figure 7, must utilize a blade that is sharp and undamaged, necessitating replacement when needed It is important to note that, even in optimal conditions, the device should not be used for more than 100 notches.

Density of PE-sheathing compounds a

0,50 to 0,65 0,30 to 0,40 a The density is for the unfilled resin, according to Clause 4 b The depth D shall be uniform along its length

Ten test pieces should be positioned with the notch facing upward in the bending clamp, as specified in section 8.2.9 The clamp must be securely closed for a duration of 30 to 35 seconds using either a vice or a motor-driven arbor press, ensuring a constant speed throughout the process.

Evaluation des résultats

Environmental stress cracking typically initiates at a notch, forming at a right angle to it The first visible sign of cracking, observed with the naked eye or corrected vision without magnification, indicates a non-compliant specimen.

After 24 hours in the heated container, the number of non-compliant test tubes must not exceed five If six test tubes are defective, the test is deemed negative However, it can be repeated once using ten test tubes from a new batch, with the same limit of five non-compliant test tubes.

Après 48 h dans le récipient chauffé, aucune éprouvette ne doit présenter de craquelure

If a single test tube has cracked, the test is deemed negative However, it can be repeated once using ten test tubes from a new batch, ensuring that none of the test tubes are defective.

Résumé des conditions opératoires et des exigences relatives aux méthodes

Conditions et/ou exigences Méthode A Méthode B

– Vitesse de refroidissement K/h voir note a

– Nombre d'essais non satisfaisants Max 5 éprouvettes

(F 0) a La température de départ varie en fonction du type de polymère

145 °C ± 2 °C pour le polyéthylène basse densité;

155 °C ± 2 °C pour le polyéthylène moyenne densité;

165 °C ± 2 °C pour le polyéthylène haute densité

Température finale 29 °C ± 1 °C b Igepal CO-630 ou tout autre réactif ayant la même composition chimique

9 Essai d'enroulement après vieillissement thermique dans l'air

NOTE L’essai d’enroulement après vieillissement thermique dans l’air est maintenant décrit uniquement à l’Article

10 Mesure de l'indice de fluidité à chaud

Généralités

The melt flow index (MFI) of polyethylene and polyethylene-based blends indicates the mass of material extruded in 1.5 minutes or 10 minutes at 190 °C through a specific die, under a defined load according to the method employed.

NOTE 1 La même méthode est spécifiée également dans l’ISO 1133

NOTE 2 L'indice de fluidité à chaud n'est pas appliqué au polyéthylène retardateur de flamme

Environment stress cracking typically initiates at a notch and propagates perpendicularly to it The initial indication of a crack, observable with standard or corrected vision without magnification, signifies a failure of the test specimen.

In a heated container, a maximum of five test pieces may fail after 24 hours; if six or more fail, the test is deemed unsuccessful The test can be repeated once with ten new test pieces, but again, no more than five failures are allowed for a passing result.

After 48 hours in the heated container, all test pieces must remain intact; if any piece fails, the test is deemed unsuccessful A retest is allowed using ten new test pieces from a different sheet, with the requirement that none of the pieces fail.

8.8 Summary of test conditions and requirements for procedures A and B

Conditions and/or requirements Method A Method B

Preparation of the test sheets:

– Failure rate Max 5 test pieces

(F 0) a Starting temperature varies according to polymer type:

Final temperature 29 °C ± 1 °C b Igepal CO-630 or any other reagent having the same chemical composition

9 Wrapping test after thermal ageing in air

NOTE Wrapping after thermal ageing in air is now covered only by Clause 10 in IEC 60811-4-2

10 Measurement of the melt flow index

The melt flow index (MFI) measures the amount of polyethylene and its compounds extruded in 1.5 or 10 minutes at 190 °C through a specific die, under a defined load according to the testing method employed.

NOTE 1 The same method is also specified in ISO 1133

NOTE 2 The melt flow index is not applicable to flame retarding polyethylene

Appareillage

L'appareillage est basé sur une extrusion plastomère, le schéma étant présenté à la Figure 8

The polyethylene within the vertical cylinder is extruded through a die under the pressure of a piston, all while maintaining controlled temperature conditions It is essential that all surfaces of the apparatus in contact with the test material are well-polished.

L'appareillage comporte les parties principales suivantes: a) Cylindre en acier

Cylindre en acier fixé verticalement et isolé thermiquement afin de pouvoir opérer à 190 °C

The cylinder must have a minimum length of 115 mm, with an inner diameter ranging from 9.5 mm to 10 mm, meeting the requirements outlined in point b) below Additionally, the base of the cylinder should be thermally insulated if the exposed metal surface exceeds 4 cm², and it is recommended to use polytetrafluoroethylene as the insulating material.

(épaisseur d'environ 3 mm) pour éviter le collage du produit extrudé b) Piston évidé en acier

The hollow steel piston must have a length that is at least equal to that of the cylinder The axes of both the cylinder and the piston should align, and the effective length of the piston is essential for optimal performance.

The maximum length of the component is 135 mm, with a head measuring (6.35 ± 0.10) mm in length The head's diameter must be less than the inner diameter of the cylinder by (0.075 ± 0.015) mm throughout the usable length of the cylinder For load calculations, this diameter must be known to within ±0.025 mm The lower edge of the head should be rounded with a radius of 0.4 mm, while the upper edge must be beveled Above the head, the piston should have a diameter of approximately 9 mm An additional device may be placed on top of the piston to support a removable mass, but the piston must be thermally insulated from this mass.

Les masses combinées de la charge et du piston doivent être telles que la force P exercée soit de

P = 21,2 N dans le cas de la méthode A (voir 10.5);

P = 49,1 N dans le cas de la méthode C (voir 10.6); d) Système de chauffage

A heating system is essential for maintaining the polyethylene within the cylinder at a temperature of (190 ± 0.5) °C The use of an automatic temperature control system is highly recommended to ensure precise temperature regulation Additionally, a temperature measurement device is necessary for accurate monitoring.

A temperature measurement device should be positioned as close as possible to the filament, integrated within the mass of the cylinder itself This device must be calibrated to measure temperature with an accuracy of ±0.1 °C.

The apparatus is basically an extrusion plastometer, the general design being as shown in

Polyethylene is extruded through a die by a loaded piston within a vertical cylinder, ensuring controlled temperature conditions It is essential that all surfaces of the apparatus in contact with the material being tested are highly polished.

The apparatus consists of the following essential parts: a) Steel cylinder

A steel cylinder fixed in a vertical position and thermally insulated for operation at 190 °C

The cylinder must have a minimum length of 115 mm and an internal diameter ranging from 9.5 mm to 10 mm, adhering to the specified requirements If the exposed metal area exceeds 4 cm², the base of the cylinder should be thermally insulated, preferably using polytetrafluoroethylene with a thickness of approximately 3 mm to prevent the extruded material from sticking Additionally, a steel hollow piston is required.

The steel hollow piston must have a length equal to or greater than that of the cylinder, with coinciding axes and an effective length not exceeding 135 mm The head measures (6.35 ± 0.10) mm in length and its diameter must consistently be less than the internal diameter of the cylinder by (0.075 ± 0.015) mm along the working length For load calculations, this diameter should be precise within ±0.025 mm The lower edge of the head features a radius of 0.4 mm, while the upper edge is rounded to remove sharpness Above the head, the piston is tapered to approximately 9 mm in diameter A stud may be incorporated at the top of the piston to support a removable load, ensuring that the piston remains thermally insulated from this load.

The combined masses of the load and the piston shall be such that the force P applied is:

P = 21,2 N in the case of method A (see 10.5);

P = 49,1 N in the case of method C (see 10.6); d) Heater

A heater to maintain the polyethylene in the cylinder at a temperature of (190 ± 0,5) °C

An automatic temperature control is strongly recommended e) Temperature measuring device

A temperature measuring device should be positioned as close as possible to the die within the cylinder's body This device must be calibrated to ensure temperature measurements are accurate to within ±0.1 °C.

Figure 8 – Appareil pour la détermination de l'indice de fluidité à chaud

(schéma montrant le cylindre extérieur à grand diamètre, la plaque de fixation A de la filière et la plaque isolante B)

Figure 8 – Apparatus for determining melt flow index (showing large external diameter cylinder, die-retaining plate A and insulating plate B)

Figure 9 – Filière (montrant le cylindre extérieur de petit diamètre avec un exemple de maintien de la filière)

Figure 9 – Die (showing small external diameter cylinder with an example method of retaining the die)

LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU. f) Filière

A hardened steel die measuring 8,000 ± 0.025 mm in length must have an average inner diameter between 2.090 mm and 2.100 mm, maintaining uniformity along its entire length within ±0.005 mm (refer to Figure 9) Additionally, the die should not protrude at the base of the cylinder.

Echantillons

A sample of insulating sheath or casing is taken from one end of the cable or wire, ensuring it has a sufficient mass This sample is then cut into pieces, with dimensions not exceeding 3 mm in all directions.

NOTE Si cela est nécessaire, le matériau isolant peut être prélevé sur des conducteurs différents.

Nettoyage et entretien de l'appareil

Nettoyer l'appareil après chaque essai

Avoid using abrasive products or any substances that could damage the surfaces of the piston, cylinder, or die when removing remaining polyethylene fragments or handling any part of the device.

Xylene, tetrahydronaphthalene, and odorless kerosene are effective solvents for cleaning It is recommended to clean the piston while it is still warm using a cloth soaked in the solvent, and to do the same for the cylinder with a brush dipped in the solvent Additionally, the die should be cleaned with a closely fitting brass rod or wooden dowel, followed by immersion in boiling solvent.

It is advisable to regularly remove the insulating plate and the fixing plate of the die, if present, approximately once a week for devices in constant use, to thoroughly clean the cylinder (see Figure 8).

Méthode A

La Méthode A convient à la détermination de l'indice de fluidité à chaud (IF) d'un échantillon de polyéthylène dont l'indice de fluidité est inconnu

Nettoyer l'appareil (voir 10.4) Avant de commencer une série d'essais, la température du cylindre et du piston doivent être à (190 ± 0,5) °C pendant 15 min; maintenir ensuite cette température pendant l'extrusion du polyéthylène

Il est recommandé que le dispositif de mesure de la température (voir point e) de 10.2) soit constitué par un thermomètre en verre à mercure fixé à demeure dans la masse du cylindre

(voir note ci-dessous) Pour obtenir un meilleur contact thermique, il est recommandé d'utiliser un alliage à point de fusion peu élevé, par exemple le métal de Wood

If a different temperature measurement system is used, it should be calibrated to (190 ± 0.5) °C before starting each test series This calibration must be done by comparing it with a mercury glass thermometer that complies with point e) of 10.2, which should be placed in the cylinder and immersed in polyethylene to the appropriate depth.

LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU. f) Die

A die of length (8,000 ± 0,025) mm made of hardened steel, the mean internal diameter being between 2,090 mm and 2,100 mm and uniform along its length to within ± 0,005 mm

(see Figure 9) The die shall not project beyond the base of the cylinder g) Balance

A representative sample of insulation or sheath must be collected from one end of the cable or wire This sample should be cut into pieces, with each piece not exceeding 3 mm in any dimension.

NOTE If necessary, the insulating material may be taken from different cores

10.4 Cleaning and maintenance of the apparatus

The apparatus shall be cleaned after each test

Avoid using abrasives or any materials that could harm the surfaces of the piston, cylinder, or die when removing superficial polyethylene or handling any part of the apparatus.

For effective cleaning of apparatus, suitable solvents include xylene, tetrahydronaphthalene, and odourless kerosene Clean the hot piston using a cloth soaked in the solvent, and use a swab dipped in the solvent to clean the hot cylinder Additionally, the die should be cleaned with a closely-fitting brass reamer or wooden peg before being immersed in boiling solvent.

For optimal maintenance, it is advisable to clean the insulating plate and the die-retaining plate, if applicable, at regular intervals, such as weekly, for equipment that is in constant use.

Method A is suitable for determining the melt flow index (MFI) of a sample of polyethylene whose MFI is unknown

The apparatus must be thoroughly cleaned prior to testing It is essential to ensure that the cylinder and piston are heated to a temperature of (190 ± 0.5) °C for 15 minutes, and this temperature should be maintained throughout the polyethylene extrusion process.

It is recommended that the temperature measuring device (see item e) of 10.2) be a mercury- in-glass thermometer located permanently within the mass of the cylinder (see note below)

A low melting-point alloy, such as Wood's metal, improves the thermal contact and its use is recommended

For accurate temperature measurements, any alternative device must be calibrated at (190 ± 0.5) °C prior to the start of each test series This calibration should be done in comparison with a mercury-in-glass thermometer, as specified in item e) of section 10.2, which should be positioned within the cylinder and immersed in polyethylene to the correct depth.

Remplir le cylindre avec une fraction de l'échantillon (voir Tableau 1) et mettre en place, au sommet du cylindre, le piston non encore muni de son poids

Four minutes after introducing the sample, during which the cylinder temperature should stabilize at (190 ± 0.5) °C, place the weight on the piston to initiate the extrusion of polyethylene through the die The extrusion speed must be measured by cutting the extruded material at regular time intervals at the die exit using a suitable cutting instrument to obtain small lengths of extruded product, referred to as "extrudates." The time intervals required to obtain these extrudates are provided in Table 1.

Prélever plusieurs extrudats pendant les premières 20 min qui suivent l'introduction de l'échan- tillon dans le cylindre Rejeter le premier extrudat ainsi que tous ceux contenant des bulles d'air

Individually weigh at least three remaining extrudates to the nearest milligram and calculate their average mass If the difference between the maximum and minimum weights exceeds 10% of the average value, discard the test and repeat using an unused fraction of the sample.

Exprimer l'indice de fluidité à chaud (IF) avec deux chiffres significatifs (voir Note 1) et l'exprimer en g/600 s suivant l'expression IF.190.20.A (voir Note 2):

IF est exprimé en grammes par 10 min; m est la masse moyenne des extrudats, exprimée en grammes; t est la durée d'extrusion des extrudats, exprimée en secondes

The hot fluidity index of polyethylene can be altered by prior thermal and mechanical treatments, with oxidation notably leading to a decrease in this index During testing, oxidation can systematically reduce the mass of successive extrudates However, this phenomenon is not observed in polyethylene that contains an antioxidant.

190 = température d'essai, exprimée en degrés Celsius

20 (ou 50 pour la Méthode C) = charge approximative, exprimée en newtons, utilisée par la détermination.

Méthode C

La Méthode C convient à la détermination de l'indice de fluidité à chaud d'un échantillon de polyéthylène dont l'indice, mesuré selon la Méthode A, est inférieur à 1

Le mode opératoire est le même que pour la Méthode A

Les intervalles de temps pour obtenir les extrudats et la masse d'échantillon à introduire dans le cylindre sont donnés dans le Tableau 1

The cylinder shall then be charged with a portion of the sample (see Table 1) and the unloaded piston reinserted into the top of the cylinder

Four minutes after the sample introduction, the cylinder's temperature must stabilize at (190 ± 0.5) °C before applying the load on the piston to extrude polyethylene through the die The extrusion rate is determined by cutting the extruded material into short lengths, known as "cut-offs," at regular time intervals specified in Table 1, using a sharp-edged instrument.

Within 20 minutes of introducing the sample into the cylinder, multiple cut-offs must be taken, disregarding the first cut-off and any that contain air bubbles At least three successive cut-offs should be weighed individually to the nearest milligram, and their average mass calculated If the difference between the maximum and minimum individual weighings exceeds 10% of the average, the test results will be invalidated, necessitating a repeat of the test with a new sample portion.

The melt flow index (MFI) shall be reported to two significant figures (see Note 1) and expressed in g/600 s as MFI.190.20.A (see Note 2):

MFI is expressed in grams per 10 min; m is the average mass of cut-offs, expressed in grams; t is the time interval of cut-offs, expressed in seconds

The Melt Flow Index (MFI) of polyethylene can be influenced by prior thermal and mechanical treatments, with oxidation notably decreasing the MFI During testing, oxidation typically leads to a consistent reduction in the masses of successive cut-offs However, polyethylene compounds that include an anti-oxidant do not display this phenomenon.

190 = temperature of tests, expressed in degrees Celsius

20 (or 50 for Method C) = approximate load, expressed in Newtons applied to the melt

Method C is suitable for determining the MFI of a sample of polyethylene whose MFI, measured in accordance with Method A, is below 1

The test procedure is the same as for Method A

The time intervals used in obtaining the cut-offs and the mass of the charge put into the cylinder are given in Table 1

L'indice de fluidité à chaud (IF) doit être exprimé avec deux chiffres significatifs (voir Note 1 de 10.5.3) et exprimé en g/150 s suivant l'expression IF.190.50.C (voir Note 2 de 10.5.3):

Applying a shorter time interval of 150 seconds with a heavier load of 50 N yields results in Scale C, which closely align with the outcomes that could have been achieved under different conditions.

Méthode A et l'Echelle A avaient été utilisées Pourtant, aucune corrélation directe n'existe entre les Echelles A et C

Tableau 1 – Masse d'échantillon à introduire dans le cylindre, pour les Méthodes A et C et intervalles de temps pour couper les extrudats, en fonction des indices de fluidité

Masse d'échantillon à introduire dans le cylindre g

11 Mesure dans le PE du taux de noir de carbone et/ou des charges minérales –

Echantillonnage

On prélève un échantillon d'enveloppe isolante ou de gaine d'une masse suffisante à une extrémité du câble On le coupe en morceaux dont les dimensions ne doivent pas dépasser

5 mm dans toutes les directions.

Mode opératoire

Heat a crucible approximately 75 mm in length to red heat, then allow it to cool in a desiccator for at least 30 minutes before weighing it to an accuracy of 0.0001 g A polyethylene sample weighing (1.0 ± 0.1) g should be placed in the crucible, and the total weight should again be measured to an accuracy of 0.0001 g Subtract the mass of the empty crucible to determine the mass of the polyethylene.

The nacelle and sample should be positioned in the center of a combustion tube made of tempered glass, silica, or porcelain, with an inner diameter of approximately 30 mm and a length of (400 ± 50) mm A stopper equipped with a thermometer is used for measurements within the specified range.

At temperatures of 300 °C and 650 °C, nitrogen is introduced at one end of the combustion tube, ensuring that the thermometer tip contacts the nacelle The nitrogen must have an oxygen content of less than 0.5% and flows through the combustion tube at a specific rate.

(1,7 ± 0,3)/min qui est maintenu durant le chauffage

En cas de doute, le pourcentage d'oxygène doit être limité à 0,01 %

The combustion tube must be installed in a furnace, with its outlet connected to two cold traps in series containing trichloroethylene, the first of which is cooled with solid carbon dioxide The outlet of the second trap should be directed into a flue or to the outside atmosphere Alternatively, it is acceptable to position the combustion tube's outlet directly outside.

The MFI shall be reported to two significant figures (see Note 1 of 10.5.3) and expressed in g/150 s as MFI.190.50.C (see Note 2 of 10.5.3):

Using a shorter reference time of 150 seconds with a heavier load of 50 N yields results on Scale C that are approximately consistent with those obtained using Method A and Scale A However, it is important to note that there is no direct correlation between Scales A and C.

Table 1 – Time intervals (as a function of melt flow index) used in obtaining the cut-offs and mass of the charge put into the cylinder for Methods A and C

Mass of the charge put into the cylinder g

11 Carbon black and/or mineral filler content measurement in polyethylene –

A representative sample of the cable's insulation or sheath must be collected from one end, ensuring it is of adequate weight This sample should be cut into pieces, with each piece not exceeding 5 mm in any dimension.

A combustion boat, measuring approximately 75 mm in length, should be heated until it reaches a red-hot temperature After heating, it must cool in a desiccator for a minimum of 30 minutes before being weighed to an accuracy of 0.0001 g Subsequently, a polyethylene sample weighing (1.0 ± 0.1) g is to be placed in the combustion boat, which is then weighed again with the same precision.

0,0001 g The weight of the boat shall be subtracted to give the weight of the polyethylene to the nearest 0,0001 g (quantity A)

The sample and boat should be positioned centrally within a combustion tube made of hard glass, silica, or porcelain, measuring approximately 30 mm in diameter and (400 ± 50) mm in length A stopper equipped with a thermometer, capable of measuring temperatures between 300 °C and 650 °C, along with a nitrogen admission tube, must be inserted at one end of the combustion tube, ensuring the thermometer's end contacts the boat Nitrogen, containing less than 0.5% oxygen, should be introduced into the combustion tube at a flow rate of (1.7 ± 0.3) l/min, which must be consistently maintained throughout the heating process.

In case of doubt, the oxygen content of the nitrogen shall be limited to 0,01 %

The combustion tube must be positioned within a furnace, with its outlet linked to two cold traps in series, each filled with trichlorethylene The first trap should be cooled using solid carbon dioxide, while the outlet from the second trap should direct fumes to a fume hood or the external atmosphere.

Alternatively, it is permissible for the outlet from the combustion tube to lead directly to the outside atmosphere

The furnace is initially heated to a temperature between 300 °C and 350 °C for approximately 10 minutes, followed by an increase to around 450 °C after another 10 minutes, and finally reaching (600 ± 5) °C after a third 10-minute period This temperature must be maintained for an additional 10 minutes After this, the outlet tube is separated from the cold traps, if used The combustion tube, removed from the furnace, is then cooled for 5 minutes under a nitrogen flow at the same rate as before.

The nacelle is then removed from the combustion tube at the nitrogen inlet side and allowed to cool for 20 to 30 minutes in a desiccator before being reweighed The mass of the residue is measured with an accuracy of 0.0001 g, referred to as quantity B of the residue.

Next, the nacelle must be reinserted into the combustion tube, and instead of nitrogen, air or oxygen is introduced at an appropriate flow rate and temperature.

(600 ± 20) °C Le noir de carbone doit ainsi brûler La nacelle est récupérée et pesée de nouveau après son refroidissement; la masse du résidu est déterminée à 0,0001 g près

Expression des résultats

Pourcentage de noir de carbone = 100%

12 Analyse du noir de carbone dans les mélanges à base de polyoléfine par thermogravimétrie

This method can serve as an alternative to the method outlined in Article 11 for determining the carbon black content in polyethylene In case of disputes, it is advisable to use the direct combustion method from Article 11 as the reference method.

Principe

Un morceau d’échantillon est chauffé dans une balance thermogravimétrique de 100 °C à

NOTE 1 Une température de début d’essai de 100 °C est pratique, comme les mesures suivantes pourront être réalisées plus tôt du fait du court temps de refroidissement

Initially, the process begins with purging using dry nitrogen that must be free of oxygen Once a temperature of 850 °C is reached, the transition is made from dry nitrogen to synthetic air This switch to air facilitates the combustion of the carbon black present.

NOTE 2 La perte de masse pendant le passage de l’azote, jusqu’à 800 °C environ, est due à la dégradation du polymère et à la perte d’autres ingrédients mineurs.

Réactifs

– Azote sec contenant moins de 10 mg/kg d'oxygène

– Air ôsynthộtique secằ (mộlange à 80 % d'azote et 20 % d'oxygốne)

The furnace shall then be heated so that the temperature is between 300 °C and 350 °C after about 10 min; about 450 °C after another 10 min; and (600 ± 5) °C after a third period of

Maintain the temperature for 10 minutes, then disconnect the outlet tube from the cold traps, if applicable Afterward, carefully withdraw the tube containing the boat from the furnace and allow it to cool for 5 minutes while continuing the nitrogen flow at the same rate.

After removing the boat from the combustion tube via the nitrogen inlet, it should be allowed to cool in a desiccator for 20 to 30 minutes before being reweighed The weight of the residue is then measured to the nearest 0.0001 g, referred to as quantity B of the residue.

The boat will be reinserted into the combustion tube, where air or oxygen will be introduced at a suitable flow rate to maintain a temperature of (600 ± 20) °C, allowing the remaining carbon black to burn Once cooled in the test assembly, the boat will be removed and weighed again, with the mass of the residue measured to the nearest 0.0001 g, representing the quantity C of residue.

12 Thermogravimetric analysis of the carbon black content in polyolefine compounds

This method serves as an alternative to the one outlined in Clause 11 for measuring the carbon black content in polyethylene In case of any disputes, the direct combustion method specified in Clause 11 will be considered the reference method.

Heat a weighed test portion in a thermogravimetric analyser starting at 100 °C with 20 K/min up to 950 °C

NOTE 1 A starting temperature of 100 °C is practical, as the subsequent measurements can be carried out earlier because of the shorter cooling time

Initially, purge the test section with dry nitrogen to eliminate oxygen Once the temperature reaches 850 °C, transition from dry nitrogen to synthetic air, which will initiate the combustion of the existing carbon black.

NOTE 2 Weight loss during the purging stage with nitrogen, up to approximately 800 °C, is due to degradation of the polymer and loss of other minor ingredients

– Dry nitrogen with an oxygen content of less than 10 mg/kg

– Dry “synthetic air” (a mixture of 80 % nitrogen and 20 % oxygen)

Appareillage

Procédé

The apparatus parameters include an initial temperature of 100 °C, a heating rate of 20 K/min, and a final temperature of 950 °C The sample mass ranges from 5 mg to 10 mg For the sweep gas, dry nitrogen is used up to 850 °C, while synthetic air is employed from 850 °C to 950 °C.

Utiliser l’appareil suivant les instructions du fabricant et les paramètres donnés en 12.4.1

Place a thin sheet of the sample at the bottom of the crucible Before starting the heating process, ensure that the atmosphere is free of oxygen by purging with nitrogen for at least 5 minutes.

The carbon black content in the mixture is determined for each sample portion by measuring the mass change during combustion at temperatures ranging from 850 °C to 950 °C in synthetic dry air The combustion residue at 950 °C also represents the ash content.

13 Evaluation de la dispersion du noir de carbone dans le polyéthylène

Généralités

Cette évaluation doit être réalisée selon l’ISO 18553 Cette méthode convient pour un mélange à base de polyéthylène ou le polyéthylène extrudé (une gaine par exemple)

NOTE Cette méthode est applicable uniquement au polyéthylène contenant moins de 3 % de noir de carbone

L’ISO 18553 donne deux méthodes pour la préparation des éprouvettes L’une et l’autre peuvent être utilisées, mais les recommandations suivantes s’appliquent:

– la méthode de compression est primitivement destinée pour les mélanges à base de polyéthylène, mais elle peut être utilisée pour le polyéthylène extrudé;

– la méthode avec le microtome est pour le polyéthylène extrudé.

Mode opératoire

Préparer le nombre spécifiés d’éprouvettes selon l’ISO 18553

En utilisant la technique d’examen au microscope donnée dans l’ISO 18553, on examine les éprouvettes pour a) le degré de dispersion, b) l’apparence du fond

The apparatus parameters include a starting temperature of 100 °C, a heating rate of 20 K/min, and an end temperature of 950 °C The weighed test portion ranges from 5 mg to 10 mg, with dry nitrogen used as the purging gas up to 850 °C, and dry synthetic air from 850 °C to 950 °C.

Follow the manufacturer's instructions and the specified parameters in section 12.4.1 to operate the apparatus Place a thin sheet of the test portion at the bottom of the crucible Prior to heating, create an oxygen-free environment by purging with nitrogen for a minimum of 5 minutes.

The carbon black content in the compound is assessed by measuring the weight change during combustion in dry synthetic air at temperatures ranging from 850 °C to 950 °C The residue left after ignition at 950 °C represents the ash content.

13 Test for the assessment of carbon black dispersion in polyethylene

The assessment shall be carried out in accordance with ISO 18553 The method is suitable for use with a polyethylene compound or an extrusion (for example a sheath)

NOTE The method applies only to polyethylene with less than 3 % carbon black content

ISO 18553 gives two procedures for the preparation of test specimens Either may be used, but the following recommendations apply:

– the compression procedure is primarily intended for use with polyethylene compounds, but may be used for extrusions;

– the microtome procedure is intended for use with polyethylene extrusions

In accordance with ISO 18553, prepare the specified number of test specimens

Using the microscopic examination technique given in ISO 18553, examine the test specimens for a) degree of dispersion b) rating of appearance

Expression des résultats

Exprimer les résultats des examens selon les données de l’ISO 18553.

Scope

This section of IEC 60811 outlines the testing methods for polymeric insulating and sheathing materials used in electric and optical fiber cables for power distribution and telecommunications, including applications on ships and offshore The specified test methods focus on PE and PP compounds, as well as cellular compounds and foam skin for insulation.

Normative references

The following referenced documents are indispensable for the application of this document

For dated references, only the edition cited applies For undated references, the latest edition of the referenced document (including any amendments) applies

IEC 60811-1-3:1993, Insulating and sheathing materials of electric cables – Common test methods – Part 1: General application – Section 3: Methods for determining the density –

Water absorption tests – Shrinkage test

ISO 18553:2002, Method for the assessment of the degree of pigment or carbon black dispersion in polyolefin pipes, fittings and compounds

For the purposes of this document, a distinction is made between low-density, medium- density and high-density PE as shown below:

Type of polyethylene Density at 23 °C a g/cm 3

High-density polyethylene >0,940 a These densities refer to unfilled resins as determined by the method specified in Clause 8 of IEC 60811-1-3

The complete testing conditions, including temperatures and durations, as well as the comprehensive testing requirements, are not included in this standard Instead, they are typically found in the specific standards applicable to each type of cable.

Toutes les exigences d’essais données dans cette norme peuvent être modifiées par la norme du câble correspondant afin de répondre aux besoins particuliers de celui-ci

The conditioning values and test parameters specified pertain to the most common types of insulation and sheathing mixtures, as well as rigid and flexible wires and cables.

5 Essais de type et autres essais

This standard primarily outlines methods related to type testing For certain tests, significant differences exist between the conditions under which type tests are conducted and those of more repetitive tests, such as individual tests; these differences are clearly specified.

Tous les essais doivent être réalisés pas moins de 16 h après l'extrusion ou la vulcanisation

(ou la réticulation), s'il y a lieu, des mélanges d'isolation ou de gainage

Several test results are obtained and ranked in either ascending or descending order The median value is the middle value of the series when the number of available values is odd, and it is the arithmetic mean of the two central values in the series when the count is even.

8 Résistance aux craquelures sous contraintes dues à l'environnement

Ces procédures d'essais s'appliquent uniquement aux granulés d'origine utilisés comme matériaux de gainage

S'applique aux matériaux soumis à des conditions et à des environnements moins sévères pour le système câblé

S'applique aux matériaux soumis à des conditions et à des environnements plus sévères pour le système câblé

This standard does not specify full test conditions, including temperatures and durations, as these should be outlined by the standard applicable to the specific type of cable.

Any test requirements which are given in this standard may be modified by the relevant cable standard to suit the needs of a particular type of cable

Conditioning values and testing parameters are specified for the most common types of insulating and sheathing compounds and of cables, wires and cords

5 Type tests and other tests

The test methods described in this standard are primarily intended to be used for type tests

In certain tests, where there are essential differences between the conditions for type tests and those for more frequent tests, such as routine tests, these differences are indicated

All the tests shall be carried out not less than 16 h after the extrusion or vulcanization (or cross-linking), if any, of the insulating or sheathing compounds

The median is the middle value of a set of ordered test results, serving as a measure of central tendency If the number of values is odd, the median is the single middle value Conversely, if the number of values is even, the median is calculated as the average of the two central values.

8 Resistance to environmental stress cracking

General

These test procedures apply only to the original granules used as sheathing materials

Applies to materials which will encounter less severe cable system conditions and environ- ments

Applies to materials which will encounter more severe cable system conditions and environ- ments

L’appareillage doit comporter les éléments suivants:

8.2.1 Presse chauffante pour fabriquer les plaques d'essai moulées, munie de plateaux plus larges que les plaques d'appui

8.2.2 Deux plaques d'appui en métal rigide de (6 ± 0,5) mm d'épaisseur et d'environ

Each plate measures 200 mm by 230 mm and features a hole on one side, allowing a temperature indicator to be positioned within 5 mm from the center of the plate.