ASTM D2669 Standard Test Method for Apparent Viscosity of Petroleum Waxes Compounded with Additives (Hot Melts)
4. Summary of Test Method
4.1 Approximately 800 g of sample are melted on a hot plate or in an oven. An 800-mL glass beaker which is jacketed with an electric heating mantle is filled with the melted sample to a level of about 25 mm (1 in.) from its top. The viscometer, with attached spindle and guard, is properly positioned. Stirring is begun and continued while the temperature of the sample is brought to slightly above the highest desired test temperature. Heating is discontinued and stirring is maintained until the sample cools to the chosen temperature. At this time, stirring is stopped and the apparent viscosity is determined. Additional determinations are made over a range of temperatures as the sample cools. Results of temperature and apparent viscosity determinations are plotted on semilog paper, and values at any particular temperature are determined from the curve.
5. Significance and Use
5.1 This test distinguishes between hot melts having different apparent viscosities. It is believed that apparent viscosity determined by this procedure is related to flow performance in application machinery operating under conditions of low shear rate. Apparent viscosity as determined by this method may not correlate well with end use applications where high shear rates are encountered.
5.2 Materials of the type described in this procedure may be quite non-Newtonian and as such the apparent viscosity will be a function of shear rate under the conditions of test. Although the viscometer described in this test generally operates under conditions of relatively low shear rate, differences in shear effect can exist depending upon the spindle and rotational speed conditions selected for the test program. Maximum correlation between laboratories, therefore, depends upon testing under conditions of equivalent shear.
