Polyformaldehyde melting point
Thread Content
The melting point of polyformaldehyde ranges from 120 to 170. I would like to ask whether, when using a melting point apparatus to determine its melting point, a high water content in polyformaldehyde has a significant impact on the measurement results? For example, more than 10%.
There should be an impact, as temperature is related to vapor pressure; when the vapor pressures of the solid and liquid phases are equal, a balance between the two phases is achieved, and the temperature at this point is the melting point. The amount of moisture present affects the vapor pressure.
As far as I know, paraformaldehyde is discussed in terms of solubility, not melting point; these are two different concepts. Generally, the solubility of polyformaldehyde is related to its degree of polymerization; at a degree of polymerization of 8–12, its solubility is 80 degrees. Those with a polymerization degree n of 12 or higher have a melting temperature of 120-170 degrees. Take a look at the other two links: 1. http://bbs.hcbbs.com/thread-314684-1-1.html 2. http://bbs.hcbbs.com/thread-273443-1-1.html
We are talking about the melting point temperature of crystals, not the dissolution temperature; as mentioned above, these are two different concepts
Polyformaldehyde is a linear polymer of formaldehyde; its degree of polymerization can be as low as around 8–10, while it can also reach around 100. Its melting point is not fixed – so what practical significance does measuring the melting point have? However, the water solubility of paraformaldehyde increases as the water temperature rises, and depolymerization occurs.
Determining the melting point is aimed at finding ways to implement it as a step in industrial processes