Tying to identigy a chloroprene ( neoprene ) family member

[magnasanti]

I have a project I am doing NOT for school I am in high school at the moment.
As the tittle suggest the project requires a sheet of an unknown family member of the chloroprene family.
I have narrowed it down to The G-type sub species. I am including 4 pictures of the rubber which needs to be I.D.
Properties of this member are good resilience, compression set, age resistance, vibration dampening. Lastly can anyone of these members be made into a foam as the pictures suggest?


Pictures

http://imgur.com/lv7fK,lDAMh,pnZA1,hkhp6#3

 

[GrahamBennett]

Although all types of rubber compound can be made as a foam by adding a blowing agent during mixing, it is unlikely that the rubber in the photographs is a foam in my opinion.

Secondly, it is almost impossible to have good resilience AND vibration damping as these are more or less mutually exclusive (you can have both at the same time).

The chances are that it is a g-type simply because this family is more popular than the w-types. The website below will give you a great deal of information regarding Neoprene.

 

[magnasanti]

I was not sure if the rubber I am trying to I.D is expanded or not. The only reason I thought it is was because it looks celled.
The project I am working on is to replicate a commercial speaker. The album of pictures above is a speaker and the rubber is between the vibrating diaphragms. which family member you'd you choose for this application?

 

[magnasanti]

Here are the family sub-types from which to choose I would hither a guess and say the g-types are most appropriate for the given application.

http://www.dupontelastomers.com/literature/neoprene/585E7A59DA93810F6B1A7900D3712585.pdf

http://www.dupontelastomers.com/products/neoprene/neoprene.asp

 

[magnasanti]

after a little more research it seems the higher the viscosity the better the dampening WD, and WHV have the highest though GD seems a little better the density for all neoprene are the same around 1.20 so with these facts I think its safe to assume the neoprene in the pictures is WD. Though would love to hear your input, the speakers are extremely hi-end 16,000 for the cheapest ones so I doubt they would go for G-types just cause there commom

 

[RubberDog]

Hello Magnasanti, I was meant to reply before, but had some urgencies.
Why are you thinking about Chloropene and these grades?

The photos you sent are little difficult to see, but for me appears more to be a foam, than actually a sponge.
The density will be related not just to the material grade, but much more to the recipe itself. And if the part is actully a sponge, the density will not be probably 1.20.

The different between the CRs are much more related to the crystalization speed and resistance to cold.

I was to be to design the piece, without looking further on other properties, as stiffness, deflection, etc, I would go with "W" grades specially due the storage shelf life (the G is more scorchy --> starts to cure faster, increase the viscosity). Also the W family has better compression set resistance.

To differenciate between the familys, probably a GC could identify the presence of sulfur or mercaptan. But I don't thing easily you could do it among the same family...

Daniel Cortarelli
Polymer Materials'Engineer

 

[magnasanti]

Hey thanks for the response Cortarelli
About the images being difficult to see did you try zooming in all the way?
I know for a fact the rubber in the images is a chloroprene family member, I got this information straight from the company who produces these speakers. I don't think DuPont released any more information such as the mechanical properties. So after all this and for the given application, as a surround for a speaker. The surround is meant to 1: allow motion 2: dampen the vibration of the diaphragm so the vibrations don't reverberate and 3: be light enough to not inhibit the movement of the diaphragm since. The best Dampener of the chloroprene family is W-types due to their high viscosity.