Tests on Polymers: Determination of Moisture
Matters contain water both attached to their surface and dependent on their molecules. This amount of water is variable in connection with external factors, especially the humidity in the air.
For this reason, matters have different weights when weighed at different times. So, it is required to dry the matter to remove the water and bring it to a constant weight before analyzing it.
The amount of moisture is the result of determining the amount of moisture from the weight loss by removing the water bound to the matter internally at a given temperature. Between moisture and dry matter;
There is a correlation of % humidity = 100-% dry matter.
The drying process is performed by keeping the matter in a drying oven and desiccator.
The matter is first weighed and then taken to the drying oven set to the appropriate temperature (105- 110 °C). The matter is left for about 1 hour and weighed again. When constant weighing is performed, the moisture on the matter is removed.
The desiccator is a closed vessel that provides a dry atmosphere. All the desiccators have the pattern of pots with a curved lid made of heat resistant, thick glass. Desiccators are used to dry matters. Matters and materials affected by the exterior atmosphere are kept dry with the help of the desiccants in the desiccator. A desiccant absorbs moisture. It takes time to dehumidify the air in the desiccator. For this reason, 2-3 hours are required for the initial drying of the air in the desiccator. With the advancing technology, measurements are carried out with a single automated instrument today.
Moisture has no effect on most polymers but hydrophilic polymers.