Experience with things like cheap foam coolers and insulation board made me write off bead foam entirely long ago as garbage.  In reality however it might be worth examining it more closely.   When one looks at the throw away food containers, and egg cartons and such, they are actually quite fine grain, and very strong fore their extremely low density / light weight.  They break easily, but they are ultra light weight and thin.  They are very low density foam.  Take the same product and triple the density, while increasing the thickness, and it may be a fairly impressive performer as a core.   The precursor material that is expanded in an oven or with steam as is done locally, obviously come in various sizes, and with different amounts of expansion agent.   The extreme fine grain material found in an egg carton, or a fast food container is far different from the courser material of an insulation board.  A cheap foam cooler is yet another grade, but apparently the precursor material can be ordered by the end product manufacturer  to whatever specification the end product requires.  I'm neither narrow or closed minded in most respects, but I have been with regard to eps foam.
   An interesting possibility with the manufacturing technique which involves a precursor that is basically a powder that expands into a monolythic block under heat, might be to include random glass fiber in the matrix... that may just be wishful thinking on my part, but random glass fiber threaded throughout the foam matrix could greatly increase the shear performance, which after all is what the foam is for in a sandwich...  The ultimate foam core would have fiber extending from surface to surface at 45 degs in every direction.... something that is not practically achievable.    fiber of course is not compatible with their manufacturing process where they make a billet and cut it into slabs.
    The whole thing makes me wonder what the various processes are for manufacturing the different products.  Some obviously are molded, others appear to have been pressed from sheet material... presumably those like egg cartons and fast food containers are pressed from sheet.   Boat building such as what we do calls for stock materials, but those materials could be manufactured using different methods and combinations of methods, just as I've been playing with heat and pressure on XPS... A secondary process to achieve the properties I want from a stock and inexpensive material.  Different processes have yielded different results, but my process control is pretty loose.   My next step is more scientific.  A platen press setup (very small) will completely contain the piece of foam in all directions.  It will be preheated in boiling water.  The foam itself will be preheated but well below softening stage, probably around 120-150F, dropped into the platen press, and compressed to the stops, taking it to 50% original thickenss, then plunged into cold water.  The idea is that the entire mass of foam will compress, but the surfaces being hotter will end up denser.   Probably a waste of time in terms of yielding useful results, but I've never regretted experimenting and learning.   I've always loved to try things.   As an example, I managed to get a consistent 2 mpg increase from my car by engineering a temperature controlled intake.   Hot at low power, cold at higher demand.... it was a process that dragged out over several years of experimenting and refining, but I could have been doing useless things with my spare time like watching TV  (never have had one of those).    More recently, I developed a soft aged spreadable cheese with the flavor profile of Swiss,  but a texture between sour cream and cream cheese.   I modified the steering on my huge forklift so that the front steers on orbital, and the rear steers in synch using sensors and valves.  It steers in opposition, or together (crab), or front only...... very much like the HPs fore and aft rudders.   Weather it's mechanical, electronic, hydraulic, or electronic or biological processes makes little difference to me......... I play with everything that interests me.  One local farmer saves about $6k a year in his operations due to a biological process I developed for him that allows him to produce a product that he used to have to buy from a manufacturer.   

                                                                                                                                    H.W.

On 07/03/2018 05:02 PM, 63urban 63urban@gmail.com [harryproa] wrote:

 

My brother in Alberta is a general contractor who sent me a bunch of literature three years ago when I was doing a major remodel. I have since lost it. But I will ask again.

Nick

Ps it's not that the beaded foam dosen't absorb moisture it does but it also dries out again at roughfully the same rate. The other absorbs it much slower but gives it up even slower.

Sent from my Bell Samsung device over Canada's largest network.

-------- Original message --------

From: "'.' eruttan@yahoo.com [harryproa]" <harryproa@yahoogroups.com.au>

Date: 2018-07-03 6:12 PM (GMT-05:00)

To: harryproa@yahoogroups.com.au

Subject: Re: [harryproa] Robs playing with polys tyrene...

 

Nick, do you have a source for that? AFAIK there has been no data suggesting that.

|In the housing construction industry things are changing due to long
|term use experience with foams. The blue and the pink foams are proving
|to slowly take on water and keep it while the bead foams breath better.
|So after twenty years the simple old beaded foam is still almost like
|new in say a roofing application while the Dow sm and like products
|have lost significant r value because of moisture loading.
|How this applies under water in boats I have no idea.
|Nick