Materials and Particle Trapping

In summary, if you want to make an acoustic panel that is resistant to glass dust, you should use felt as the filler material. Felt is also a good alternative to plastic for acoustic panels.
  • #1
icor1031
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1
Please excuse me if this isn't a physics question - I'm not sure where it belongs.

Felt, such as this: http://www.ebay.com/itm/Felt-by-the-YARD-Craft-Supplies-36-INCHES-X-36-INCHES-square-100-polyester-/261301533508

And 3mil plastic sheeting, as this: http://www.homedepot.com/p/Husky-8-Ft-x-100-Ft-Clear-3-mil-Plastic-Sheeting-CF0308C/202184057

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How small of a particle size, will those block?
For example: if I throw a .3 micron particle at the felt, will it go through?
How about the plastic?

Thanks!
 
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  • #2
Assuming your medium is air and the 0.3 um particle is traveling slowly, it will not pass through the 0.003” plastic film, it will probably get caught up for some time in the felt. You could increase the chance of a particle being caught by the felt if you dampen the felt with oil or water. The felt is behaving like a HEPA filter.
See; http://en.wikipedia.org/wiki/HEPA
 
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  • #3
Appreciated, friend.
 
  • #4
Note that felt is usually made from sheep's wool which has a diameter of about 20 um.
To reliably trap 0.3 um particles requires a fibre size closer to 1 um.
It is probable therefore that ordinary felt will only trap particles of 6 um and greater.
 
  • #5
Baluncore said:
Note that felt is usually made from sheep's wool which has a diameter of about 20 um.
To reliably trap 0.3 um particles requires a fibre size closer to 1 um.
It is probable therefore that ordinary felt will only trap particles of 6 um and greater.

By chance, are you familiar with mass loaded vinyl? How would it do? :)

http://www.ebay.com/itm/2lb-Mass-Loaded-Vinyl-4-x-10-40-sf-MLV-/120775275480?pt=US_Acoustical_Treatments&hash=item1c1ec473d8
 
  • #6
Mass loaded vinyl will not pass air, let alone 0.3 um particles.

What are you trying to accomplish here?
How much area of filter do you need?

You can buy rolls of HEPA filter material such as these.
http://www.alibaba.com/showroom/hepa-filter-cloth.html
You can search for your local supplier.
 
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  • #7
Baluncore said:
What are you trying to accomplish here?

It's for making acoustic panels. The MLV is for diaphragm resonators, and the felt/plastic are for porous absorbers.
I'm probably going to fill both with Mineral Wool, and I want to avoid fibrosis. ;)

I asked about felt, as a possible alternative to plastic. But that won't work, as you pointed out.

Thanks again!
 
  • #8
Baluncore said:
Mass loaded vinyl will not pass air, let alone 0.3 um particles.

I'm back, again. :)

My plastic sheeting (seems to be .31mil, not 2mil) is causing issues @ 2.5kHz, even with 1 layer of felt on top of it.So, my question: How well will satin work to block particles? It says "100% polyester."
If that won't work well, is there a material that you would suggest?

Thanks!
 
  • #9
I presume you are using the plastic film to stop glass dust escape.
What problems does plastic film cause at 2.5 kHz.

The thickness of plastic sheet will determine it's mass per unit area and resonance frequency.
It will behave differently if it has a crumpled surface or if it is bonded to the felt.

100% polyester satin is a woven polyester fibre, so it will probably not stop fine dust. You would need a bonded polymer film material such as is used to make car covers or disposable coveralls for contaminated sites. If it is waterproof it will probably stop fine dust.

Sound absorption comes from a sandwich of different materials with multi-faceted surface orientation. For example, used egg cartons glued to a surface can make a big difference.
 
  • #10
Baluncore said:
Sound absorption comes from a sandwich of different materials with multi-faceted surface orientation. For example, used egg cartons glued to a surface can make a big difference.

That is one method, but "flat" acoustic panels (often used as internal dividing walls in office buildings) basically work like a transmission line with impedance changes along its length, to let the energy get "inside" the panel and stop it getting out again.

The purpose of the filling material (rock wool etc) is to provide a huge surface area relative to the volume of the internal cavity, to absorb the kinetic energy (i.e. the sound) in the air into the viscous boundary layer in the air surrounding each individual fiber. Loudspeaker cabinets are filled with the same type of material for the same reason.
 
  • #11
Baluncore said:
What problems does plastic film cause at 2.5 kHz.

The SPL is high, similar to not using a panel. I'm not sure about decay time, or anything else.

It's okay, it goes away if I use *two* layers of felt. :)

Thanks again, be well.
 

FAQ: Materials and Particle Trapping

1. What is the purpose of particle trapping in materials?

Particle trapping in materials is used to control the movement and behavior of microscopic particles within a system. This can be done for various purposes, such as filtering contaminants, separating mixtures, and creating new materials with specific properties.

2. How does particle trapping work?

Particle trapping typically involves creating a physical barrier or using electric or magnetic fields to confine particles in a specific area. This can be achieved through various techniques such as optical trapping, acoustic trapping, and dielectrophoresis.

3. What types of materials are commonly used for particle trapping?

Materials that are commonly used for particle trapping include polymers, metals, and various forms of carbon such as graphene and carbon nanotubes. These materials often have unique properties that make them suitable for particle trapping applications.

4. What are the potential applications of particle trapping in materials science?

The potential applications of particle trapping in materials science are vast. Some examples include creating advanced filters for water and air purification, developing new drug delivery systems, and improving the efficiency of solar cells and batteries.

5. What are the challenges associated with particle trapping in materials?

One of the main challenges with particle trapping in materials is finding the right balance between trapping strength and flexibility. Too much trapping force can damage the particles, while too little can result in particles escaping the trap. Additionally, the development of efficient and cost-effective trapping techniques is an ongoing challenge in the field.

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