CoreCork core material

[groper]

Ive just been enlightened on this material by a supplier who was rather enthusiastic about its potential in my boat build... http://www.corecork.amorim.com/clien...page.asp?id=10

The mechanical properties by themselves dont look good when compared to PVC foams or similar. However, the mechanical properties improve once the sandwich structure is laminated as the resin forms pillars within the core material and improves the compressive and shear properties without adding too much excessive weight.

http://www.corecork.amorim.com/clien...%20GENERAL.pdf
According to the data sheet for a 6mm cork core infused panel once an epoxy resin is introduced, a shear strength of 0.9Mpa is achieved and compressive strength increased to 2.2Mpa -still not great numbers for high strength structural work- but still adequate for many purposes including small boat hulls or light structural applications.

It would seem this could be a good choice for many applications based on its low cost, high flexibility and/or contourability and compatibility with all common fibreglassing resins and production methods. Especially appealing is its ability to form complex shapes and bend into very tight radii without the need for cutting and joining etc.
http://www.corecork.amorim.com/clien...0as%20Core.pdf

Im interested in learning more from people that have used or have experience with corecork...

[Herman]

Due to its relatively low shear modules, it has great impact resistance. The stiffness needed for a given structure can be matched by increasing the thickness slightly. I know of rough water canoes, that have a good survival rate, due to the cork core.

Indeed the product is very gentle to work with. It does not create dust, it does not snap, etc. It just looks odd. Water absorption is extremely low, it is rot free, fire resistant (will char, but not burn).

I have used it in a sailboat, made from "green" materials, like Sicomin Greenpoxy, Cork and flax. This all worked fine.

[groper]

Some infusions done with cork core...

Using the NL10, 140kg/m3 no transfer media or perforations are required for the infusion to happen on both sides of the core, there is ample flow through the core itself. Lightweight panels are realised with core thicknesses upto 10mm, beyond this, foam core panels are lighter due to foams lower density itself and less resin trapped in the core.

Thin cored panels are about the same weight as foam, as the resin normally consumed by the surface of the foam = the resin trapped between the cells of the cork. Have the added benefit of less resin wasteage and no transfer media waste.

Worth a look if your doing laminates with thin cores...

[Herman]

I have rolls of 3mm available, if someone needs it.

[groper]

What are the main drawbacks with this material herman?

Im thinking of using it in the bilge of my 35ft catamaran hulls - mainly due to its ease of conforming to shape. The laminate ill be putting over it is a reasonably thick outer skin of glass for impact resistance, maybe 3-4mm thickness infused in a female mold with 10mm corkcore and an inner skin of around 1.5mm. Above the bilge i was then wanting to use PVC foam core for the topsides from a different mold...

[Herman]

They only drawback I can imagine is its relatively low shear modulus.

[groper]

i dont quite understand herman... according to the corecork datasheet, its shear modulus exceeds that of 80kg/m3 airex once the resin is introduced?

Do you mean compressive modulus? This is the only mechanical property that i can see isnt comparible to PVC foam once the resin is introduced...?

Im worried that this unique low compressive modulus core will start to delaminate if subjected to many compressive cycles and the resin webs between the cork cells start to breakdown....?

[Herman]

I had some samples in 3mm thickness, with laminate on both sides. These felt a bit flexible. However, I did not have foam to compare with. So you might be right.

Compressive is bad news for skin buckling. I have no decent data on dynamic failure of the resin, this is highly resin dependant. Epoxy is relatively ductile.

In canoes, the 3mm works perfectly. However how much dynamic cycling does it see?

[latman]

I infused 5 different sample laminates with corecork and VinylEster resin and they all failed horribly (there were also 5 done with PVC foam and Soric cores and they were fine) If you are going to try anything new DO A TEST!

[idkfa]

What was the mode of failure?

Any ideas where you went wrong?

[latman]

there must be a chemichal in the cork that inhibited the curing/bonding of my VE, all the skins were cured but barely attached to the core , I used light kevlar and carbon skins (60-160) GSM with 1 and 2mm cores and when they pulled apart you could smell the resin quite strongly.

edited to add photo

[latman]

Originally Posted by idkfa

What was the mode of failure?

Any ideas where you went wrong?

yes my VE and cork are not compatible as shown by a test.

[tunnels]

Originally Posted by groper

What are the main drawbacks with this material herman?

Im thinking of using it in the bilge of my 35ft catamaran hulls - mainly due to its ease of conforming to shape. The laminate ill be putting over it is a reasonably thick outer skin of glass for impact resistance, maybe 3-4mm thickness infused in a female mold with 10mm corkcore and an inner skin of around 1.5mm. Above the bilge i was then wanting to use PVC foam core for the topsides from a different mold...

Why would you use Cork for a core !! it has no place in a boat structure except as a floor over lay !! thats all !! If you use it in any part of hull structure you got to be kidding yourself !! Wake up man !! smell the flowers !!

[Herman]

Tell me why, or why not, instead of to smell flowers, mr. tunnels.

[tunnels]

Originally Posted by Herman

Tell me why, or why not, instead of to smell flowers, mr. tunnels.

First question i ask is where did it come from ( what was its intended use ) and what is it meant to be used for !!Sound like from the building industry !!
Cork is just the bark off a tree by nature it has no strenght or grain or guts by its self its just the resin that holding it together you might as well be using paper pulp soaked in resin . if i was told to use it any where on any job i would simply walk away !!! it has no place any where in the boating industry and certinly no for what you want to use it for . In nz long time agao we used to use a product called Pinex !! a simular concept but soft ! when soaked with resin went nice and hard and quite ridged !, was used for making panels and glassed over ok for non structual stuff and had a limited useable life a couple of years and then stuffed as in totally . The silly forman i worked with in the first boat place i started used in in the deck of his 28 foot yacht , In less than a year the skins had separated and come apart and hung down he even put wood on the deck and batterns inside the boat and screwed through to hold it . Naturally the word got round and he couldnt sell his boat ! At least foam has a little bit more guts .
Sorry but its a deffinite no not never dont even think about it from me
I AM 110% AGAINST ITS USE ANY WHERE IN A BOAT, LIKE ANYWHERE !! when it falls apart in a years time just remember i told you so!!!
WE also had water proof partical board !!and resin soaked 100% water proof mdf ! Non of these products work !!and the people that use then should have known before they even signed the cheques to pay for it . Its rubbish !! its Man made rubbish !!! shame on you for even considering it !!