ISO 11443-2021 pdf free download – Plastics — Determination of the fluidity of plastics using capillary and slit-die rheometers.
Measurements can be made using a range of values of the preset parameter (either applied test pressurein method 1, or volume flow rate in method 2).
lf a slit die with pressure transducers positioned along its length and also upstream of the die entryis used, then entrance and exit pressure drop values can be determined. lf capillary dies of the sameradius but of varying lengths are used, then the sum of the entrance and exit pressure drops can bedetermined.
A slit die with pressure transducers positioned along its length is particularly suited for automatedmeasurements using online computer evaluation.
Recommended values for capillary die dimensions and for flow rates and temperatures to be used intesting are presented either in the relevant clauses below or in ISO 11403-2.
ln using a slit die, either the aspect ratio H/B between the thickness H and the width B of the slit is smallor else a correction for H/B(see Annex A) is necessary. In the latter case, the calculated quantities aredependent on assumptions made in deriving the correction formulae used, notably that elastic effectsare irrelevant.
5 Apparatus
5.1Test device
5.1.1 General
The test device shall consist of a heatable barrel, the bore of which is closed at the bottom end by aninterchangeable capillary or slit die. The test pressure shall be exerted on the melt contained in this barrel by a piston, screw, or by the use of gas pressure.Figure 1 and Figure 2 show typical examples.Other dimensions are permitted.
5.1.2 Rheometer barrel
The barrel shall consist of a material resistant to wear and corrosion up to the maximum temperatureof the heating system.
The barrel can have a lateral bore for the insertion of a melt-pressure transducer close to the dieentrance.
The permissible deviations in the mean bore diameter throughout the length of the barrel shall be lessthan ±0,007 mm.
The barrel shall be manufactured using techniques and materials that produce a Vickers hardnesspreferably of at least 800 HV 30 (according to lSO 6507-1 and Note 1) and a surface roughness of lessthan Ra=0,25 um (average arithmetic discrepancy, according to IS0 4287).
NOTE 1 For temperatures up to 400 °C, nitrided steel has been found suitable.Materials of hardness valueslower than that specified but of sufficient corrosion and abrasion resistance have been found to be acceptable forconstruction of the barrel and dies.
NOTE2 An increase in barrel-bore diameter increases the number of measurements that can be made with asingle barrel filling and increases the shear rate range of the instrument. Disadvantages of using a larger barrel-bore diameter are that larger sample masses are required and that the time necessary to reach temperatureequilibrium throughout the sample is greater. The barrel-bore diameters of commercially available rheometerslie in the range between 6,35 mm and 30 mm.
5.1.3 Capillary dies (method A)
5.1.3.1 The entire length of the capillary die wall shall be machined to an accuracy of ±0,007 mm forthe diameter (D) and 主0,025 mm for the length (L) (see Figure 1).
The capillary shall be manufactured using techniques and materials that produce a Vickers hardnesspreferably of at least 800 HV 30 (according to IS0 6507-1 and Note 1 in 5.1.2j and a surface roughness ofless than Rg = 0,25 um (average arithmetic discrepancy, according to ISO 4287).
The capillary opening shall show no visible machining marks or perceptible eccentricity.
NOTE1 Diameters of capillary dies typically used lie in the range between 0,5 mm and 2 mm, with variouslengths to obtain the desired L/D ratios.For testing of filled materials larger diameters can be required.
NOTE2 Hardened steel, tungsten carbide, stellite, and hardened stainless steel are the most common diematerials.
NOTE3 The precision with which capillary dimensions can be measured is dependent upon both the capillaryradius and the capillary length.With capilaries of diameter smaller than 1,25 mm the specified precision(±0,007 mm) is difficult to obtain. Due to the extreme sensitivity of flow data to capillary dimensions, it isimportant that the capillary dimensions, and the precision with which the dimensions are measured, are knownand reported.This also applies to the dimensions (thickness, width, and length) of slit dies (see 5.1.4).ISO 11443 pdf download.