why are yu guys using neopren (Chloropren) for damping?

George Necola · Post by **George Necola** » Sun Sep 04, 2005 10:36 pm

hi guys,

with my knowledge of elastomerphysics I'm wondering why u using expensive neopren instead of EPDM or natural rubber (called Natur-Gummi in German).

Neopren is manufactured by dupont (so it's the name of the product) and the same as Chloropren (chemical name). It's oil-resistant.

EPDM has quite the same properties like Neopren but it's only waterresistant and not oil.

If I look from the physical-side on the products:
- EPDM has a better compression set than neopren (I talk about 60 SHORE A)
- natural rubber has quite the same compression set as the above mentioned but lacks the oil and water responsibility..

thanx for listening dudes;)

knightfly · Post by **knightfly** » Mon Sep 05, 2005 1:48 am

George, welcome; you must be seeing older posts or ones from newer members; I don't recommend neoprene for just the reasons you mentioned. In fact, if people have the budget I don't recommend EPDM either, in most cases; it doesn't have nearly the damping of other, more expensive materials such as sylomer, or even butyl for some applications.

Where people want to float a floor, there are more factors involved than I totally understand (not being a mechanical engineer) but if using EPDM (which also has the advantage over neoprene in life expectancy) in a wooden floated floor I always recommend a mineral wool fill with slight compression in order to damp the floor.

Ideally, everyone would use a 6" concrete slab floated on 2" thick sylomer blocks over a 12" concrete slab, etc - but when you're forced to deal with a second story that's already built, it's not too practical (or safe) -

I'm really glad to see a new member with knowledge of this type material, looking forward to learning from you and hope I can reciprocate... Steve

Post by **sharward** » Mon Sep 05, 2005 3:22 am

knightfly wrote:. . . if using EPDM (which also has the advantage over neoprene in life expectancy) . . .

Steve, have we ever seen any documented proof of EPDM having "the advantage over Neoprene in life expenancy"?

As I've said before, I took the EPDM-based Auralex U-boats off my list because of their acknowledgement that they have not done extensive testing of the product.

I also offer my welcome to George!

--Keith

George Necola · Post by **George Necola** » Mon Sep 05, 2005 5:39 am

hi guys;)

nice to meet ya!!

I worked for an international company called HUBER & SUHNER AG. We made gasmasks, rubberammunition and also civilstuff like rollers for spinmachines, pvc-roles for printingcompanys.. now I changed working in an atomic-researchcompany and studying informatics..

my father is a teacher as an polymer-physics-teacher..

long blah...

sorry guys..

EPDM and other rubber has pros and cons... there is no "Ultimate rubber-solution":. I will search for some testresults..!!

sorry, it's getting late here.. I will post tommorow..

cya

knightfly · Post by **knightfly** » Mon Sep 05, 2005 6:16 am

Kieth, only documented proof I have is personal experience with cords on power tools, etc - as you know, I'm old enough to have seen this personally

I have some tools whose power cords started to split within 5 years, others lasted 10, none have escaped longer than 15 - I've not looked for specific info embossed into the cords to be sure, but most used to be made with neoprene (known to electricians as "S-cord", newer stuff is usually labeled "SO cord" -

Only thing I have for longevity on EPDM is a personal phone conversation with Jeff Szymanski of Auralex (and I think an email) where he claimed one reason for U-boat's cost was using EPDM instead of neoprene because of the longer life expectancy - 25 years vs. 10.

We've all since learned (mostly from Eric and Paul) that this isn't cast in stone but instead depends a lot on loading, etc - and in fact I've seen bridge pads claiming 25+ year life that use neoprene waffles.

Oh well, why should this be any easier than the rest of the quest?? Steve

George Necola · Post by **George Necola** » Mon Sep 05, 2005 2:25 pm

Only thing I have for longevity on EPDM is a personal phone conversation with Jeff Szymanski of Auralex (and I think an email) where he claimed one reason for U-boat's cost was using EPDM instead of neoprene because of the longer life expectancy - 25 years vs. 10.

hi knightfly!

the problem is, if you are talking about EPDM in general is the following:

there are 100'000 (a lilbit too much maybe) diffrent mixtures of EPDM. You can have EPDM not vulcanized, then it's like bubblegum or strong treated EPDM with Shore's up to 80 Shore A!! you can mix in 100 more components to make it stable or resistant for chemical substances..

THis is the problem with EPDM.. you have to focus then on a product called XY by company XZ (the same like neoprene.. chemicly, like I mentionend before, it's chloroprene, but with this certain amount of material A and the treatmentprocess B it's called neoprene and It should have the same properties in China and in US.. ).

I will get some more information on diffrent EPDM-structures and materials.. maybe we can work something out.

the point to watch is for shure the longtime stabilty and the compression set value.

and for shure, if you build your studio, it's not like the pyramids.. maybe you have to change the rubber before 2000 years pass by..

Post by **sharward** » Mon Sep 05, 2005 3:13 pm

Steve, yes, I was aware of your conversations with Jeff on the subject. Not that I am suggesting that Jeff is anything but truthful... But in my opinion the conversational assurances from him, which appear to be based on conversational assurances from his suppliers, sprinkled with some anecdotal power tool cord personal experiences that may or may not be applicable to the question at hand, lead me to the conclusion that there is no conclusion, scientifically speaking. I like seeing charts and graphs and documentation and certifications, especially when we're talking about studio shoes that can't be removed without chopping off the studio's legs to get to them.

That being said, I shall continue my duty to call into question the wisdom of the use of U-boats or EPDM in general whenever I see it mentioned here, until and unless actual evidence to the contrary is made available, or until I just get bored of it.

George, I'm really looking forward to seeing more contributions from you!

George Necola · Post by **George Necola** » Mon Sep 05, 2005 11:08 pm

something short I worked out today.. my englishtranslatioin sucks.. if you don't understand what I mean, ask..