ASTM D3236 Standard Test Method for Apparent Viscosity of Hot Melt Adhesives and Coating Materials
10. Report
10.1 Report the apparent viscosity at a given temperature along with the details of the instrument model, the spindle number and rotational speed. Example: Apparent viscosity at 125 °C (Model RVT viscometer, SC 4-28, spindle, 20 r/min) - 20 000 mPa·s.
11. Precision and Bias
11.1 The precision of this test method was determined in an interlaboratory study using six representative wax-based hot melt materials. Tests were conducted at three temperatures by seven to eleven laboratories using four instrument models and seven spindles from a single manufacturer. Each spindle was appropriately tailored to the viscometer.
11.1.1 Repeatability - Within laboratory variability may be described using the repeatability value (r) obtained by multiplying the repeatability relative standard deviation by 2.8. The difference between two test results, obtained by the same operator with the same apparataus under constant operating conditions on identical test material would, in the normal and correct operation of the test method, exceed the following values in one case in twenty:
8.8% of the mean of the two results.
11.1.2 Reproducibility - The between laboratory variability may be described using the reproducibility value (R) obtained by multiplying the reproducibility relative standard deviation by 2.8. The difference between two single and independent results obtained by different operators working in different laboratories in identical test material would, in the long run, exceed the following value only in one case in twenty:
25.4% of the mean of the two results.
11.1.3 A review of that portion of the data which can be considered comparable at equal shear rates indicates that those laboratories capable of comparing data at equal shear rates can expect improvement in reproducibility. It is estimated that under conditions of equal shear rate reproducibility, the values would in the long run, exceed the following in one case in twenty:
15 % of the mean of the two results.
11.1.4 A summary of data generated in this interlaboratory test program is shown in Table 1 and Table 2.
11.2 Bias - The procedure in this test has no bias because the value of apparent viscosity can be defined only in terms of a test method.
12. Keywords
12.1 adhesives; apparent viscosity; coating materials; hot melt adhesives; rotational viscometry; viscosity
