The PDFs do not show density anywhere I can find.   The Dow web page, unlike the other Dow web page where I previously looked does show the densities of the foams as being from 1.3 PCF to 3 PCF for the Highload 1000.  The foam I've been experimenting with that I thought was 2 PCF is listed as a type IV at only 1.55 PCF.   It's worth noting that the compressive strength to weight ratio is NOT linear.  Dividing compressive strength by density in PCF, we get 22 for the 40, 29 for the 60, and 33 for the 100.   Imagine what the compressive strength of a 5 PCF XPS would be.... probably in excess of 200 psi, and right in the ballpark with divinicell H80 (218).     H-45 shows 87 psi.   The Highload 60 is the same density as H35, which has a compressive strength of 65.3 pounds per square inch compared to 60 for the XPS.   
      When looking at an application like a deck, the same density of XPS versus Divinicell has only slightly less compressive strength.   The other mechanical properties are not particularly relevant in that sort of application.   

    As I can get the 1.5 pcf XPS insulation foams from local yards, and they are from the same manufacturers, it is likely that the 3 PCF foams could be special ordered in full bundle quantities, and ordered that way on a stock order, it probably would be economical.

    The ability to flex and recover from deformation of pressure and impact is more important than just compressive strength.    XPS is probably better in a crush structure in the bows than something like divinicell assuming it is not as elastic.   Crushing or crumpling of a structure absorbs energy better than elastic deformation which stores energy and rebounds.  

    I would personally have no hesitation whatsoever in using this higher density XPS in bulkheads, beams, decks, and other upper structure.....   a from a structural standpoint.  Time, labor, and process might make the difference.  If for example it does not lend itself well to infusion, resulting in more labor and resin use that could be a factor.  Availability in the desired thickness might be another factor.  I can almost guarantee that it won't be a normal stock item at any supplier within hundreds of miles.   I would expect that a city 500 miles from my current location would be the nearest likely source, based on past experience.   I would expect to be able to get it reasonably only in pallet quantities, but I would also expect the cost to be in the range of 10% of the cost of Divinicell.    5 or 6K worth of foam (Divinicell) in the context of building a 30' catamaran, considering that it is core for the entire boat, really is not a big price.  If half that were 100 pcf XPS, both cost and weight go down.  Cost from 6K to perhaps 3500.   A savings of 2500 dollars maybe.    If the intelligent infusion process doesn't work well with XPS, that changes the equation.   Knife cutting. drilling, surface prep like my flash blasting, adding a flow media, etc............   It all adds to time and cost, and whittles away at that 2500 to the point that it might not work out at all.   Weight savings in foam for 25 sheets would only amount to about 89 pounds..........about a 5% increase in payload.....another anchor, more chain, an additional battery........ take your pick.     89 pounds in the context of a light catamaran is not an insignificant savings.


                                                                                              H.W.


On 05/18/2018 10:33 PM, '.' eruttan@yahoo.com [harryproa] wrote: