ASTM D1505-18 pdf free download.Standard Test Method for Density of Plastics by the Density-Gradient Technique.
7.2.1 Place a tall cylinder in the constant-temperature bath maintained at 23 ± 0.1 DC. Fill the cylinder about two thirds full with a solution of two suitable liquids selected from Table I. the density of which can be varied over the desired range by the addition of either liquid to the mixture. Alter the cylinder and solution have attained temperature equilibrium, place the float in the Solution, and if it sinks, add the denser liquid by suitable means with good stirring until the float reverses direction of movement. If the float rises, add the less dense liquid by suitable means with good stirring until the float reverses direct ion of movement.
7.2.2 When reversal of movement has been observed, reduce the amount of the liquid additions to that equivalent to
0.001-gkm1 density. When an addition equivalent to 0.0001- g/cm3 density causes a reversal of movement, or when the float remains completely stationary for at least 15 nun, the float and liquid are in satisfactory balance. The cylinder must be covered whenever it is being observed for balance, and the liquid surface must be below the surface of the liquid in the constant-temperature bath. After vigorous stirring, the liquid will continue to move for a considerable length of time: make sure that the observed movement of the float is not due to liquid motion by wailing at least 15 mm alter stirring has stopped before observing the float.
7.2.3 When balance has been obtained, till a freshly cleaned and dried pycnometer with the solution and place it in the 23 ± 0. I C bath for sufficient time to allow temperature equilibrium of the glass. Determine the density of the solution by normal methods and make "in vacuo” corrections for all weighings. Record this as the density of the float. Repeat the procedure for each float.
7.3 Gradient Tube Preparation (see Annex AI for details):
7.3.1 Method A—Stepwise addition.
7.3.2 Method B—Continuous tilling (liquid entering gradient tube becomes progressively less dense).
7.3.3 Method c—Continuous tilling (liquid entering gradient tube becomes progressively more dense).
8. Conditioning
8.1 Test specimens whose change in density on conditioning is greater than the accuracy required of the density determination shall he conditioned before testing in accordance with the method listed in the applicable ASTM material specification.ASTM D1505 pdf download.