BS ISO 16790:2021 pdf download

BS ISO 16790:2021 pdf download.Plastics-Determination of drawing characteristics of thermoplastics in the molten state.
BS ISO 16790 specifies a method for determining the drawing and break characteristics of molten plastics. The method involves the measurement of the force generated in deform ing a molten filament under defined extrusion temperature and drawing conditions.
Data is generated under non-isothermal and non-homogeneous deformation conditions. However, it is useful for the interpretation of polymer behaviour in extensional flow.
The method is suitable for thermoplastics moulding and extrusion materials that can be extruded using a capillary extrusion rheometer, or an extruder with capillary rod die or other extrusion devices and have sufficient melt strength to be handled without difficulty.
The method is applicable to chemically stable materials that produce a uniform extrudate free from heterogeneities, bubbles, unmelted impurities, etc.
BS ISO 16790 can provide information on
— processability for all extrusion techniques,
— the effect of mechanical and thermal history, and
This technique is one of a number of techniques that can be used to measure the extensional flow behaviour of a material. This method of measurement does not necessarily reproduce the drawing conditions to which thermoplastics are subjected to during their processing.
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 291. Plastics — Standard atmospheres for conditioning and testing
ISO 11443. Plastics — Determination of the fluidity of plastics using capillary and slit-die rheometers
3 Terms and definitions
For the purposes of BS ISO 16790, the following terms and definitions apply.
Molten polymer is extruded from a capillary rheometer, extruder or other extrusion device at a specified temperature. The extrudate is drawn from the die by take-off wheels. Two techniques are used.
a) A series of take-off wheel velocities is used to determine the drawing force as a function of the drawing velocity.
b) A constant rate of acceleration of the take-off wheels is used to determine the melt strength (force to break) of the extrudate.
5 Apparatus
5.1 Apparatus for heating the polymer and forming the extrudate
5.1.1 General
The device to supply the molten polymer at a controlled temperature and flow rate shall consist of a heatable barrel [either a capillary extrusion rheometer (5.1.2) or an extruder (5L3)], the bore of.BS-ISO-16790-2021

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