ISO 11443-2021 pdf free download.Plastics一Determination of the fluidity of plastics using capillary and slit-die rheometers.
This document specifies methods for determining the fluidity of plastics melts subjected to shear stresses at rates and temperatures approximating to those arising in plastics processing. Testing plastics melts in accordance with these methods is of great importance since the fluidity of plastics melts is generally not dependent solely on temperature, but also on other parameters; in particular shear rate and shear stress.
The methods described in this document are useful for determining melt viscosities from 10 Pas to iO PaSs, depending on the measurement range of the pressure and/or force transducer and the mechanical and physical characteristics of the rheometer. The shear rates occurring in extrusion rheometers range from 1 s1 to 106 I.
Elongational effects at the die entrance cause extrudate swelling at the die exit. Methods for assessing extrudate swelling have also been included.
The rheological techniques described are not limited to the characterization of wall-adhering thermoplastics melts only; for example, thermoplastics exhibiting slip” effectsl1Jl2i and thermosetting plastics can be included. However, the methods used for determining the shear rate and shear viscosity are invalid for materials which are not wall-adhering. Nevertheless, this document can be used to characterize the rheological behaviour of such fluids for a given geometry.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements 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.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
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— IEC Electropedia: available at http://www.clectropedia.org/
Measurements can be made using a range of values of the preset parameter (either applied test pressure in method 1, or volume flow rate in method 2).
If a slit die with pressure transducers positioned along its length and also upstream of the die entry is used, then entrance and exit pressure drop values can be determined. If capillary dies of the same radius but of varying lengths are used, then the sum of the entrance and exit pressure drops can be determined.
A slit die with pressure transducers positioned along its length is particularly suited for automated measurements using online computer evaluation.
Recommended values for capillary die dimensions and for flow rates and temperatures to be used in testing are presented either in the relevant clauses below or in ISO 11403-2.
In using a slit die, either the aspect ratio H/B between the thickness H and the width B of the slit is small or else a correction for H/B (see Annex A) is necessary. In the latter case, the calculated quantities are dependent on assumptions made in deriving the correction formulae used, notably that elastic effects are irrelevant.
5 Apparatus
5.1 Test device
5.11 General
The test device shall consist of a beatable barrel, the bore of which is closed at the bottom end by an interchangeable 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 temperature of the heating system.
The barrel can have a lateral bore for the insertion of a melt-pressure transducer close to the die entrance.
The permissible deviations in the mean bore diameter throughout the length of the barrel shall be less than ±0,007 mm.
The barrel shall be manufactured using techniques and materials that produce a Vickers hardness preferably of at least 800 HV 30 (according to ISO 6507-1 and Note 1) and a surface roughness of less than Ra = 0,25 pm (average arithmetic discrepancy, according to ISO 4287).ISO 11443 pdf download.