Bulk density > 1.36g/cm^3

[Mantawa]

Hello,

I am trying to find a plastic in pellet form that has a bulk density greater than 1.36g/cm^3.

Do any of you know of one?

 

[patprimmer]

I suspect Bronze filled material might.

I know one manufacturer makes 85% Bronze filled nylon and also a heavily filled PP.

I will look up some details tomorrow.

If I forget, remind me

Regards

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.

 

[Mantawa]

Thanks.

 

[Pud]

If you need more than 1/2 tonne. it be worthwhile getting it made. LNP used to make (in Europe) a Tungsten powder filled nylon for making ammunition (indoors - goes through people, stops at walls).

This stuff is dense at a sg of 2.3 but data sheet very limited:

http://www.silon.eu/datasheets/taboren/PH82B75.pdf

As Pat stated, bronze might do it - it's all custom stuff though.

Application sounds intriguing...

Cheers


Harry

 

[Demon3]

Yes, put fillers in it. What other properties do you need?

Modulus, yield strength, impact resistance etc.

By the way, the density of a polymer does not increase linearly as you add a certain weight % of filler. Rather the density of filled polymers varies linearly with the volume % of each component.

I just mention this because if you shoot for a density of 1.36 you will miss unless you calculate based on volume percentages.

There is not any memory with less satisfaction than the memory of some temptation we resisted.
- James Branch Cabell

 

[patprimmer]

The company that makes the Bronze filled is Duromer Products in Sydney. I do some consulting to them, so I have a small interest.

The bronze filled was also developed for munitions, some as the projectile in rifles etc, some for if I told you I would have to shoot you stuff.

It has also found application as bearings, but the tensile and elongation are really poor.

Duromer would probably do less than 1/2 tonne of such a special compound, but at a considerable premium.

The cost premium is worked out by a simple formula. Add the cost of an extra 100 Kg to cover waste when cleaning and starting up and add 3 hour to the time portion of the cost.

A number of people also offer barium sulphate filled materials (most commonly PP)for more common heavy applications. This will not be as heavy as the others mentioned here but may be off the shelf items. A very common application is weights for vertical venitian blinds.

I don't know of the top of my head the conversion between packing density and SG, but it will vary a bit due to variations in pelet geometry.

Regards

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.

 

[Demon3]

40 weight % CaCO3 in PP gives 1.23 g/cm3 and the density of that filler is only 2.7 so you can easily get to 1.36 using fillers without resorting to metals.

The two most common high density, inert, cheap fillers are:

1. Barium sulfate (barytes or blan fixe)
2. Magnetite (see

http://www.minelco.com

and look for the tradename MagniFi

http://www.minelco.com/index.asp?Id=8&prodId=40)

The former is white with a density around 4.5 whereas the latter is black with a desnity of 5.0.

There is not any memory with less satisfaction than the memory of some temptation we resisted.
- James Branch Cabell

 

[patprimmer]

Demon3

They need a packing density, not an SG of 1.36.

The SG will need to be at least 50% higher, possibly nearly twice as high, depending on pellet geometry.

Regards

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.

 

[Demon3]

Aha! Thanks Pat. That's a lot harder to achieve of course. I guess the pellets will only pack with ~60% efficience so you'll need a density of the polymer material of 1.36/0.6=2.25

I have an Excel sheet I made that allows you to input filler and polymer density and it plots the density of the composite versus weight % filler (a curve).

I will see if I can find that file and put in some numbers.

There is not any memory with less satisfaction than the memory of some temptation we resisted.
- James Branch Cabell

 

[Mantawa]

I was interested only in the bulk density (pellet form). I suspect the application will let a few of you down. I'm looking at different materials to use in a counterbalance application. We will not be molding the plastic for this one. Mold polymers came to mind because they can be very inexpensive.

Thanks to everyone who replied, I appreciate it.

 

[dwightdixon]

For a counter balance, does it really have to be pellets? You might use common stone if it packs well. Why would you need a specific bulk density anyway, aren't you just looking for a fixed amount of weight??

 

[Demon3]

Try searching Matweb by density...

http://www.matweb.com/

There is not any memory with less satisfaction than the memory of some temptation we resisted.
- James Branch Cabell

 

[Mantawa]

Dwight,

Bulk density is a concern because the application is centrifugal.

I'll look at matweb.

Thanks.

 

[patprimmer]

Mantawa

The very high density plastics will not be cheap. I would try sand or lead shot or glass beads.

Regards

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.

 

[Demon3]

Pat's suggestion of glass beads is a good one. You can get hollow glass beads too with different densities from Potters for example.

There is not any memory with less satisfaction than the memory of some temptation we resisted.
- James Branch Cabell

 

[Demon3]

Interestingly, when I worked in the household appliance industry, we used lots of materials but formulations for counterweights for washing machines were the most varied. Materials used include:

Concrete with iron slag particles
PP with iron slag particles
Epoxy with iron slag particles

Iron has a density of about 8gcm-3.

There is not any memory with less satisfaction than the memory of some temptation we resisted.
- James Branch Cabell