ISO 2555:1989 pdf free.Plastics — Resins in the liquid state or as emulsions or dispersions — Determination of apparent viscosity by the Brookfield Test method.
ISO 2555 specifies a method of determining an apparent viscosity, by the Brookfield Test method, of resin.s in a liquid or similar state, using one of the types of rotational viscometer described in this Standard.
The application of this method to specific products is detailed in annex A.
2 Principle
A spindle, of cylindrical or related form (disc), is driven at a constant rotational frequency in the product being studied. The resistance exerted by the fluid on the spindle, which depends on the viscosity of the product, causes a torque which is indicated by a suitable meter. This measurement may be based on tightening of a spiral spring depending on the torque, indicated by the movement of a needle on a dial.
The apparent viscosity by the Brookfield Test method is obtained by multiplying this dial reading by a coefficient which depends on the rotational frequency and characteristics of the spindle.
The products to which this International Standard is applicable are generally non-Newtonian and the measured viscosity depends on the velocity gradient to which the products are subjected during the measurement.
With these types of viscometer, the velocity gradient is not the same for every point of the spindle. Thus, for a non-Newtonian fluid, the result is not strictly the true “viscosity at a known velocity gradient” and therefore is conventionally called the apparent viscosity.
3 Apparatus
3.1 Brookfield-type viscometer, type A, B or C, chosen according to the product to be tested and the desired precision.
4 ChoIce of rotational frequency and spindle
Choose the rotational frequency-spindle combination taking into account lIit value of thu viscosity tu b masuwiJ, the desired precision and the velocity gradient. It Is necessary to make this choice in such a way that no measurement corresponds to less than 20 % or more than 95 % of full-scale deflection. However, for the best accuracy It is advisable to keep to the range 45 % to 95 % of full scale.
If a comparison of viscosities between non-Newtonian products Is desired, it is necessary to use the same rotational frequency-spindle combination for all the measurements, even if the accuracy of one of the measurements is markedly decreased.ISO 2555:1989 pdf download.