[PSUBS-MAILIST] alternative syntactic foam

[hank pronk via Personal_Submersibles]

Alan,Yes I have been running numbers but with polyester resin witch is a bit less.  That is pretty darn cheap, pity I wasted 1,100 on trawl floats ;-(  I will likely spend more to make foam for 12,000 feet for my next sub, Elementary 12000   The plan is build elementary 3000 so that I can swap out the occupant sphere with a sphere the same size but rated for 12,000 feet.Hank 

    On Monday, June 19, 2017 4:07 PM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
 

 Hank,I have just looked at some figures on the 3M 5500 psi glass micro spheres  on Ebay.They are talking about a 50/50 ratio of spheres to epoxy resin. I don't know if you canuse less resin than this.Resin weighs 1.1 grams per cubic centimetre, spheres are .38, so in a 50/50 mix you get .26 gram buoyancy per cubic centimetre, or 260 grams per cubic litre. You need to be 550 lb. buoyant, or 256kg. You would need 100 litres of mix to get this.In a 50/50 mix that would cost 50 x $18:72 = $936 for the spheres & based on a priceof $400- for a 16 litres pack of epoxy, ($25 per litre) it would cost 50 x 25 = $1250for the resin. Total of $2186.You might be able to get the price down buying in bulk.Cheers Alan


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On 19/06/2017, at 1:51 PM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:



Hank,c have you had a look at this stuff...http://www.ebay.com/itm/MICROSPHERES-GLASS-BUBBLES-LOW-DENSITY-EPOXY-SYNTACTIC-FOAM-FILLER-1-GAL-1-5-KIT-/220528963762One gallon in volume for $18:72. It says it crushes to 90% of it's volume at 5500 psi.And yes, enjoy a bit of detective work.Cheers Alan

Sent from my iPad
On 19/06/2017, at 12:19 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:


Hi All,Just been thinking  about low cost ways to make foam.  I am sure at the end of the day, I will make my foam the standard way, but it is still an interesting subject to explore.  I have learned that microspheres are added to many things, even concrete.  That got me thinking, if the compressive strength is there, the best product to reinforce the spheres should be the lightest possible material.  Polypropylene is very light and has a compressive strength of 6,000 psi.  The fun part about Polypropylene is, it can be recycled from bottle lids etc.  I don't think it would take to much imagination to build an oven with a mixer inside and a microsphere injection port.  Polypropylene has a specific gravity in the neighbourhood of .7g\cc that means a light weight foam can be made with microspheres and no macro spheres.    I don't know about the water absorption properties yet.Hank

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