Volume Resistivity of Polyurethane 2

[Senselessticker]

Is there a materials standard out there somewhere that gives a volume resistivity value for polyurethane? I know there are many different kinds of polyurethane, but is there a reference somewhere for just polyurethane without getting into the various trade names associatted with this polymer? Any help is greatly appreciated.

 

[patprimmer]

I am sure Bayer (the company that invented polyurethane) could quote figures for their PU grades.

Different grades and even different colours of the same grade can have different values, so any general data with no mention of grade is at best unreliable, probably to the point of being useless or even dangerous.

If a wrong value is used in calculations to test a design, it could result in danger of electrocution or fire, so I suspect no responsible source would publish an unreliable figure, and therefore any source that did publish a general figure, could be considered unreliable.



Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Pud]

Hi,

LNP specify a value of 10^13 Ohm.cm for the two grades they supply and the base polymer they use - viz. 20% GF, and 15% PTFE + Si oil and the unfilled.

As Pat has noted - don't bet your house on it - check specifics!!!!

As an aside, a quick browse suggests PU being on the low(ish) end of VR. e.g. Polystyrene 10^15, ABS 10^15, PC 10^16, POM 10^16, PEEK 10^16, PP 10^16, etc., etc.


Rgds

Harry

 

[Senselessticker]

Thanks Pat and Pud for you helpful information. The material in question is actually Adiprene. I was able to locate some adiprene properties online. I do not recall the exact range of values, but most of the adiprene products ranged from 10^13 - 10^17 ohm-cm. The client (very plainly) told me to pick a "general" / "average" resistivity value for Polyurethane. So I picked 10^13 ohm-cm to run the calc. I cited the fact that this resistivity value was generic, and in order to produce accurate calcuations, the specific product properties would need to be used. I also included a minumium resistivity value needed to meet there specs for current leakage. This value was somewhere around 10^6. I suppose its difficult to produce calcs when the client will not give me the specific material used or even the properties associated with it. In any case, they were satisfied with the paperwork. I'm a new engineer, and just don't want to leave myself vunerable. I stated very clearly in the report that the calculations were assuming values, and should not be relied upon for specification without knowing the specific property data. In the design engineering world...have I "covered my rear", in this case?

 

[Pud]

Hi senselessticker,

i guess you've covered the rear with a copy of the yellow pages......

You could always add the caveat that end users should verify products in use...


rgds


harry

 

[IRstuff]

http://www.azom.com/details.asp?ArticleID=683

shows hard-case polyurethane volume resistivity on the order of 10^12 ohm-cm

TTFN