cvermeulen;943106; said:
Nope, you are wrong. It does absorb water. That is why it warps. Take a dry sponge and wet only one side. As that side absorbs water and grows, it will warp the sponge.
drip plates
- Thread starter cvermeulen
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Nope, you are wrong. It does absorb water. That is why it warps. Take a dry sponge and wet only one side. As that side absorbs water and grows, it will warp the sponge.
CHOMPERS;944607; said:
OK, don't take this the wrong way, it's just my nature to question everything
do you have a source for that? I'm really interested to learn more... I can't say I'm ready to believe that, it seems too weird!A materials engineering class.
I doubt you will find anything worthy on the net, but stop in at any good library, preferably at a university.
I doubt you will find anything worthy on the net, but stop in at any good library, preferably at a university.
Acrylic is an ammorphous material; its molecules do not arrange in a crystaline structure. Water molecules can enter into interstitial spaces and move deeper into the surface layer through diffusion. The extra density on that side causes compressive strain in the plane of that surface. The strain and higher density causes the material to bow just like a bimetalic thermal element.
CHOMPERS;944918; said:
Snowballer.
My materials Eng classes stuck mostly to metals
.Still seems weird to me, like it should go cloudy or something if it's absorbing water... or not be suitable for long term aquarium construction use... I'll look into it, I love stuff like that.
If acrylic absorbs water, would that mean that the mass of the acrylic sheet exposed to water would be greater than the mass of one not exposed to water?
Not that I want to do the experiment
Not that I want to do the experiment
cvermeulen;944955; said:Snowballer.
My materials Eng classes stuck mostly to metals
Still seems weird to me, like it should go cloudy or something if it's absorbing water... or not be suitable for long term aquarium construction use... I'll look into it, I love stuff like that.
And the number of intellects keep growing
No, it doesn't cloud like other materials. It is a property of acrylic that makes it suitable for use in aquariums and windows. The bowing is a bonus in aquarium use. It bows in the direction of the water. Thus the bowing created by the water absorption helps counter the bowing from the water pressure.
dogofwar;945484; said:If acrylic absorbs water, would that mean that the mass of the acrylic sheet exposed to water would be greater than the mass of one not exposed to water?
Not that I want to do the experiment
The question you are trying to ask is whether the density is higher, and the answer is yes. The higher density causes the material to expand. If only one side expands, the material will bow because that side is now larger than the other side.
As far as mass, since the material has taken on more mass, it must be more massive. If you were to measure the same volume of material (trimming after absorption) then it should be less massive because water is less dense than acrylic (acrylic sinks in water). However, there are compressive forces in the acrylic/water material. An acurate weighing would be very difficult because the amount of water actually absorbed is incredibly small. For every ten thousand acrylic molecules, there are approximately seven spaces for a water molecule to enter. Keep in mind that the acrylic bows only a little and it takes about a month to get there. If it absorbed water like a sponge, it would contort to unusable configurations.
I have tried to use acrylic for my drip tray, but I end up cracking it. Probably cause im using a wood bit. Do they make special bits for drilling acrylic?
I'm a Mechanical Engineer myself, but I think I missed this during Strength of Materials or Hydraulics. The amount of data on MFK is simply mind-boggling! We used to be just aquarium hobbyists. These days however, an MFK'er must be an engineer-biologist-chemist-sociologist-carpenter-meteorologist-geologist-research analyst, plus an accomplished financial genius to afford all these expensive set-ups and rare monster fish! We rock!CHOMPERS;946298;946298 said:
