I'm trying to measure the porosity of some silk scaffolds I made. From some papers I read, they did a hexane displacement method to measure the porosity. Part of the methodology states that they did a quick evacuation-repressurization cycle to completely evacuate the pores from air and replace it with hexane. Initially, I thought of using the vacuum oven. However after reading the MSDS of hexane (toxic, flammable), I now have second thoughts of doing this. Can anyone suggest an easy and safe way of performing an evacuation-repressurization cycle? Is just any vacuum pump compatible with this?
Make sure you have a cold trap to catch solvent going to the pump. I would skip the vacuum oven though; if you have the sample in the solvent in a tube, put a drilled bung or cork the end of the vacuum tubing and just attach it briefly ( a few times, with release in between) to the tube: evac and release a few times and you should be rid of air. You can also help this along by brief ultrasonication (put the tube with the sample in the liquid in an ultrasonic bath few a few seconds: this also tends to displace trapped air)
Considering data for the boiling point of n-hexane at the low vacuum range (760 to 25 mm Hg), you have to deal with the fact that (liquid) n-hexane boils by approx. 121 mm Hg at 20 ºC (taken as room temperature). Cf. J. G. Speight (Ed.), "Lange's Handbook of Chemistry", 16th ed., 2005, McGraw-Hill (Table 2.37).
Hi christine
I want to do same work to in order to porosimetry of my PCL scaffold.
but i not sure about this method.
as U know we have some open pores and some close ones.
I think If we use n-hexane to porosimetry, we just measurement open pores because n-hexane cant access to close pores and it will be a big error in our tests.
what are U think about this?
best regards
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