Air-tight storage boxes for nylon filament?

[Ama-fessional Molder]

An example, from this paper:
http://www.simar-int.com/files/vortrag_engl.pdf

example 25 °C temperature and 80 % R.H. the air is containing19 g H2O / cbm air! Heating up the air from 25 °C to more than80 °C is reducing the R.H to less than 10 % but there are still 19 g ofwater per cbm drying air

Heating the air reduced the RH, but the water content remained exactly the same, and in many cases the actual water content can still remain above the recommended moisture content of the plastic. If that is true, then you will never be able to suitably dry the plastic no matter how long it stays in the box, or how far you increase temperature to reduce RH.

Furthermore, elevated temperatures are absolutely necessary to begin the process of drying any hygroscopic materials. The water actually binds to the polymer chains of hygroscopic materials, and heat is required to break the water molecules free.

So, while you can achieve very dry air at 5c and 5% RH, the air temperature is not sufficient to unbind the water from the plastic at the molecular level. All you will do with those parameters is reduce the surface moisture.

I just took this picture less than a minute ago. This is the control panel of a several thousand dollar industrial plastic dryer. It uses heated air and dual desiccant beds with automated bed regeneration to maintain a specific dewpoint, in this case -40 degrees. The plastic being processed here is polysulfone, which has a melt processing point of approximately 630f or 330c, hence the high drying temperature.



You will note that RH is nowhere to be seen. In fact these units don't even have the ability to measure or display RH.


I'm also extremely enthusiastic about my work, in case you haven't noticed.