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Determination Viscosity for pseudo-plastic foam concentrates

Date of issue:2020-06-10 19:35 Number of visits:

Determination of Viscosity for pseudo-plastic foam concentrates

NOTE The procedure is described in EN ISO 3219:1994, Annex A or Annex B.
D. l Pseudo-plastic foam concentrates
Pseudo-plastic foam concentrates have a viscosity which decreases with increasing shear rate at constant temperature.
NOTE Pseudo-plastic fbam concentrates are a particular class of non-Newtonian foam concentrate.
D. 2 Viscosity determination
D. 2.1 Apparatus
D. 2.1.1 Rotational viscometer in accordance with EN ISO 3219 with the following parameters:
— maximum shear stress > 75 Pa;
— maximum shear rate 2 600 s_1.
The viscometer shall be fitted with a temperature control unit which can maintain the sample temperature within ± 1 °C of the required temperature.
D.2.2 Test temperatures
The viscosity of the foam concentrate shall be measured from 20 °C, to and including the lowest temperature for use claimed by the manufacturer in steps of 10 °C. Use a fresh sample for each temperature.
D.2.3 Viscosity measurement
If the sample contains suspended air bubbles the sample shall be centrifuged for 10 min using the apparatus specified in C.2.1 and C.2.2 before the sample is applied in the apparatus.
The test should be performed in accordance with the following test procedure:
1) adjustment of temperature control unit;
2) setting of the gap;
3) application of the sample;
4) minimum 10 min waiting period (no shear) to reach temperature equilibrium;
5) 1 min pre-shearing at 600 s_1;
6) 1 min waiting period without shearing;
7) measure the shear stress for 10 s at each shear rate starting at the lowest shear rate (preferable at 75 s-i).
Measure the shear stress at least at 8 different shear rates up to 600 s~ e.g. 75 s-】,150 s-〔, 225 s", 300 s-1, 375 s・i, 450 s_1, 525 s_1, 600 s_1. Calculate the apparent viscosity from the Formula (D.l):
Apparent viscosity ymPa- s) = 1000 x 出一(D.l)
Shearrate I I
D.2.4 Results
Report the results as a table including test temperature (°C), shear rate shear stress (Pa), and apparent viscosity (mPa s).