ASTM D2569 Standard Test Method for Distillation of Pitch
9. Procedure
9.1 Weigh 100 more or less 1 g of the sample into a tared distillation flask. Assemble the apparatus as described in Section 8.
9.2 Set the control on the electric heater so that the sample of pitch completely melts, but does not boil, in not less than 10 min nor more than 30 min. Reset the control to provide a voltage or amperage reading which, in past experience on a similar type of pitch, has given a distillation rate of between 0.03 and 0.05 g/s for the total distillate between 300 and 360°C. Do not change this setting during the course of the distillation.
9.3 When the distillate begins to condense in the side arm, start heating the condenser with a small gas flame to lower the viscosity of the first distillate and to prevent the deposition of solids. Continue heating as required throughout the distillation, but keep the temperature of the condenser low enough to ensure complete condensation of the vapors.
9.4 Collect the fractions in tared receivers, changing them as the thermometer indicates the maximum temperature for each. Unless otherwise specified collect the following fractions:
to 270°C
270 to 300°C
300 to 360°C
9.5 Do not change the position of the thermometer during the distillation. Make no correction for the emergent stem of the thermometer, but if the barometric pressure at the time of the distillation lies outside the range of 756 to 765 torr (101 to 102 kPa), change receivers at the adjusted temperatures shown in Table 1.
9.6 If the first drop of distillate falls from condenser below 300°C, start the timer as the receiver for the 300°C fraction is put into place. When the maximum temperature for the test (see Note 1), corrected for barometric pressure if required, is reached, replace the receiver by another flask, stop the timer, shut off the heater, and remove the cover from the shield as quickly as possible. If the first drop falls from the condenser at a temperature above 300°C, start the timer as it falls into the receiver.
NOTE 1 - The distillation should not be carried to a temperature above 360°C. At this point the temperature of the residue in the flask is near 450°C, the temperature at which pitch begins to decompose. Decomposition will make the results meaningless.
9.7 Calculate the distillation rate by dividing the weight, in grams, of the distillate betweeen 300 and 360°C by the time, in seconds, required to collect it. If the rate falls outside the limits of 0.03 to 0.05 g/s, discard the results and repeat the test with an appropriate adjustment of the heater control setting.
