ISO 11443:2021 Plastics — Determination of the fluidity of plastics using capillary and slit-die rheometers

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Plastics — Determination of the fluidity of plastics using capillary and slit-die rheometers是于2021-02发布的ISO标准，适用于国际范围。

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标准部分原文

Plastics — Determination of the fluidity of plastics using capillary and slit-die rheometers

1 Scope

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 Pa∙s 7

to 10 Pa∙s, 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 −1 6 −1

rheometers range from 1 s to 10 s .

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 [1][2]

thermoplastics melts only; for example, thermoplastics exhibiting “slip” effects 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.

ISO 1133-1, Plastics — Determination of the melt mass-flow rate (MFR) and melt volume-flow rate (MVR) 

of thermoplastics — Part 1: Standard method

ISO 1133-2, Plastics — Determination of the melt mass-flow rate (MFR) and melt volume-flow rate (MVR) 

of thermoplastics — Part 2: Method for materials sensitive to time-temperature history and/or moisture

ISO 4287, Geometrical Product Specifications (GPS) — Surface texture: Profile method — Terms, definitions 

and surface texture parameters

ISO 6507-1, Metallic materials — Vickers hardness test — Part 1: Test method

ISO 11403-2, Plastics — Acquisition and presentation of comparable multipoint data — Part 2: Thermal 

and processing properties

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:

— ISO Online browsing platform: available at https://w ww .iso .org/o bp

— IEC Electropedia: available at http://w ww.e lectropedia. org/

ISO 11443:2021(E)

3.1

Newtonian fluid

fluid for which the viscosity is independent of the shear rate and of time

3.2

non-Newtonian fluid

fluid for which the viscosity varies with the shear rate and/or with time

Note 1 to entry: For the purposes of this document, this definition refers to fluids for which the viscosity varies only with the shear rate.

3.3

apparent shear stress

τ

ap

fictive shear stress to which the melt in contact with the die wall is subjected, expressed in pascals (Pa)

Note 1 to entry: It is calculated as the product of test pressure and the ratio of die cross-sectional area to die wall area.

3.4

apparent shear rate



γ

ap

fictive shear rate that the melt at the wall would experience at the observed volume flow rate if its −1

behaviour were Newtonian, expressed in reciprocal seconds (s )

3.5

true shear stress

τ

actual shear stress to which the melt in contact with the die wall is subjected, expressed in pascals (Pa)

Note 1 to entry: It is estimated from the test pressure p by applying corrections for entrance and exit pressure losses, or is directly determined from the melt-pressure gradient in the channel.

Note 2 to entry: For the purposes of notation, the absence of a subscript is used to denote true values.

3.6

true shear rate



γ



shear rate obtained from the apparent shear rate γ (3.4) by taking into account the deviations from ap

Newtonian behaviour by appropriate correction algorithms (see Note in 8.2.2), expressed in reciprocal −1

seconds (s )

Note 1 to entry: For the purposes of notation, the absence of a subscript is used to denote true values.

3.7

viscosity

η

 

viscosity in steady shear, defined as the ratio τγ/ of true shear stress τ (3.5) to true shear rate γ (3.6), expressed in pascal seconds (Pa∙s)

3.8

apparent viscosity

η

ap

ratio τγ/  of apparent shear stress τ to apparent  shear  rate γ (3.4), expressed in pascal ap

ap ap ap

seconds (Pa∙s)

3.9

Bagley corrected apparent viscosity

η

apB

 

ratio τγ/ of true shear stress τ (3.5) to apparent shear rate γ (3.4), expressed in pascal seconds (Pa∙s)

ap ap

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