Industrial Melamine (3)

5.

5.

In the sublimation device, the sample is heated under negative pressure, and after the melamine is completely sublimed, the residue is weighed , and the purity of the melamine is measured

5.

The vacuum sublimation device of the sample must meet the following conditions, and its structure is shown in Figure 1

a) The material of the sample container is platinum, glass, magnets, etc.

b) The vacuum sublimation device shall adopt a heating device and a vacuum device with a temperature control internal temperature of (305±10) ℃ and an internal pressure of below 4.

5.

a) Weigh about 2g of the sample (accurate to 0.

b) Put the sample container into the decompression sublimation device, after it is completely sealed, turn on the vacuum device to slowly attract, and reduce the pressure to 0.

c) The temperature in the adjusting device reaches (305±10)℃ within about 20 minutes from the start of suction:

d) Continuous sublimation under the pressure 0.

e) Stop heating and suction, let the pressure in the device slowly return to normal pressure, and then take out the sample container;

f) After cooling to room temperature in a desiccator, weigh the mass of the sample container (accurate to 0.

5.

The purity is expressed by the mass percentage X _{1 of} melamine , calculated according to formula (2):

Where; m—the mass of the sample, g;

m ₁ —The mass of sample residue: g;

X ₂ —Moisture calculated according to 5.

Take the arithmetic mean of the two parallel determination results as the determination result

Figure 1 Diagram of sublimation device