I simply mixed aluminium powder with PDMS ( 50% by weight) and stirred it for 15 minute to mix it properly. After mixing, I cured it to form a layer. I checked the conductivity of this layer but it showing no conductivity. Please suggest me better way to make PDMS conductive with aluminium powder.
Hello Krishnanand .. ,
What do you mean by "no conductivity"? Granted, Aluminium is not the most conductive metal, yet you should still have some reading? What is your measurement setup?
How are you contacting your resultant material? For instance, are you using some form of highly-conductive "landing pad" to place the measurement probes on?
Also, are you restricted to Aluminium?
Jules
Usually gold, silver and platinum nanoparticles are used for making conducting PDMS.
I think your Al oxidized to AL2O3 during stirring but most likely during the curing step. How did you cure? Under normal ambient conditions in air? If so, try mixing and curing under N2 flow avoiding O2 and H2O reacting with the Al. If this does not work it is still possible that the Al reacts with the PMDS (containing O) during curing and forms oxides or compounds that do not conduct. Then the only alternative is a noble metal like Au or Pt. But first try the curing without oxygen and water present.
Not all the Al particles will be oxidised during the process of stiring and curing. So definitely it should show a value. So check your equipment procedure carefully. I think you might use four probe apparatus
1. Surface of Al quickly develops a native oxide film and so your powder probably already had an oxide coating before being added to the PDMS. Simple mearurement of resistivity on a piece of Al using hand-held probes, the pressure is usually enough to penetrate the oxide (a few nm thick) but with your powder in PDMS with is not so easy.
2. Once you have a cured layer of PDMS/Al the surface will have a thin film of PDMS over the exposed Al particles and so making electrical contact to them is not guaranteed - plus penetrating through the possible oxide coating on the particles adds to this.
3. Even without (1) and (2) are you sure your %loading is high enough? When I used carbon micropowder, the loading had to be quite high.
4. Using gold or silver or platinum powder would be better.
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