Alkaline stress & cracking of acrylic fibres

Alkaline stress cracking acrylic fibres

I posted this on reefcentral a while back. I hope its helpful.

I have an acrylic sump right now that i got from glasscages. I paid almost $400 for it. 5 Months later, cracks everywhere . I thought it was a poorly built sump until i did more research on acrylic and found out that overtime, the chemical stress of alkaline solutions can cause breaks in the molecular bonds, causing a chain reaction which then cause the acrylic fibers to crack.

This is research article from the Department of Materials Science and Engineering, Massachusetts Institute of Technology.

The article stated that high temeperature caused acrylic to crack faster. Salt solutions cause less than 7% shrinkage in acrylics fibers. But even if you get a tiny little scratch, it causes a chain reaction which will eventually lead to a crack, especially the areas that already experience physical stress,(in our case) the baffle joints and bent corners of fish tanks or sumps. This doesn't happen with glass.

here is the link to the MIT article "Chemical stress cracking of acrylic fibres". Its in pdf format.
http://www.springerlink.com/content/...7/fulltext.pdf

Acrylic is not as durable as glass. It's more reactive to chemicals and cannot be cleaned with alcohol, extremely alkaline solutions, and also in high temperatures. Acrylic is stronger than glass and can appear to take more abuse initially but overtime, the cost, reactive nature of it and long term issues are something to think about.

 

Interesting.

Maybe that is why my minibow 2.5g I had at work on my desk ended up getting stress cracks all over it after a year. I would never even put a betta in it now.

 

When i read that article, it made so much sense to me. Then examined the acrylic with a maginfying glass and holy moly! 100s of tiny cracks everywhere.