Carbon fibre

[david chan]

In the “New back pack -MYOG” thread Bill Fornshell says that he can either use titanium or carbon fibre at about 1/3 the weight. He was talking specifically about a framesheet.

Anyone out there with experience of laminating carbon fibre/epoxy (canoe builders perhaps?) care to comment on this? Is this sort of fabrication generally a better bet for weight than titanium? Is there a rule of thumb that says “you can do it x% lighter in carbon fibre/epoxy?

David

[paul johnson]

David, if no one else replies with an answer, when I’m back on day shift next week, I’ll ask one of our material scientists your question. They do a lot of work in both materials.

[Bill Fornshell]

This is the web site I an looking at for
Carbon Fiber Sheet

I need to buy a piece 14″ by 20″ for what I want. It is 0.015″ thick and 2.465oz. The Titanium is 0.016″ thick. The weight of each seems to come out at or near -Ti 0.049oz per sq inch, Carbon Fiber 0.00882oz per sq inch. I need about 140 sq inches for the frame.

The price of the Carbon Fiber and the Titanium is almost the same. $75 and change.

[D G]

Bill,
You should look at this stuff called aerogel and carbon nanofoam:

http://en.wikipedia.org/wiki/Aerogel

[D G]

Bill,
You should look at this stuff called aerogel and carbon nanofoam:

http://en.wikipedia.org/wiki/Aerogel

From the descriptions, this stuff is a real good insulator, feels like foam, has one of the lowest densities (ie lightest) of any material known to man.

I have no idea where to get this stuff or how expensive it is but it sounds like it’s on the cutting edge!

It sounds like you can probably make a sub 0.5 oz full length sleeping pad with this stuff.

Cheers
Dan

[kevin davidson]

I believe that it is not weight supporting— oops, I stand corrected, there now are some weight supporting forms…. It is a form of unobtainium— that is, if you aren’t a NASA or defense subcontractor, it’s almost impossible to find.
It would make for some fabulous building insulation.
I think it has application in certain high-end speakers, as well.

I want some. I see that some very small samples are available on Ebay.

[Bill Fornshell]

Daniel,
The Aerogel is some interesting looking stuff. I think it is still a while off but may show up in a few years. I expect for now it is to expensive and going to very special uses.

I think something called by a similar name or close was used in some cold weather clothing. It seems to have only been used one year for some reason. I called the company that was making it but all production was sold out.

[D G]

There is that 2.5 kg brick being supported by a 2 gram piece of aerogel!

So this stuff seems pretty strong. It has some interesting properties if you read the description. Apparently when you press it with force it feels like hard styrofoam, but if you press it too hard it shatters like glass.

I calculated based on the density of one of the lightest versions that a sleeping mat with dimensions of 3/8 by 20 inches by 72 inches would weigh like 0.06 oz. They say it has great insulating properties.

I saw the stuff sold on ebay too, but they are tiny samples :(

[Mike Barney]

http://www.unitednuclear.com/aerogel.htm

[Michael Demchak]

man it really would be great to have some of this stuff, might make a good suport for a backpack, and awsome sleeping pad… but a sample the size of a little bigger then your thumb costs 130$, better make that a torso sized pad….

[Victor Karpenko]

I have worked with Aerogel a number of times. The real light weight Aerogel has been described as solid smoke. It can be fragile and tough at the same time. I have a small sphere about 1 inch in diameter. It bounces fairly pretty good. It is not a suitable material for sleeping pads or backpacks. Any abuse, and it will fracture or crumble. It is a great insulating material if you can support it with out crushing it.

[J R]

If anyone knows where to get a flexible Aerogel blanket, Id appreciate it.

Ive talked with aspen aerogels about obtaining one of their blankets for possible use as a sleeping bag or even as a sleeping pad (sandwiched between more durable fabrics).

Now I just want some to make cold weather insoles.

They flat out refused to sell it, even though they *said* it would work for everything I threw at them except a sleeping bag or clothing.

[Vick Hines]

Bill,
I’ve done a lot of work with carbon fiber and glass in canoe building and other projects. It is practical to make a carbon fiber frame sheet starting from scratch. Trouble is, you will spend more than $75. And if this is your first attempt at working with composites, you may waste time and material. I wouldn’t recommend it unless you are already familiar with the processes and are ready to spend the bucks to experiment with different layups. I cannot do more than ballpark what would work.

Carbon cloth usually costs about $30 per yard for 36-40 inch widths. But you might consider using a mix of carbon and S-glass – a treated glass that has improved adhesion to epoxy or a Kevlar/carbon mix. More flexible than the glass mix, but even stronger and almost as light as the graphite alone. Both are lots cheaper and perform better than carbon alone. Not as rigid, but less likely to fail catastrophically. Much of the weight is in the resin anyway.

I would use a thin form core – 1/4 to 1/8 inch. It will double the strength. You will still probably need to mold in some structural shapes (like channels) for rigidity.

Here is where I would start: Two layers of 100% carbon cloth ($30) – one on each side of Rohacel foam 1/8″ (about $15) Any hobby epoxy such as West System, Eager or System Three (I prefer either of the latter two. You will need one quart of each epoxy component – total 2 quarts. Cost ranges widely – from $35 to $60 for both quarts. I would not consider using polyester resin.

I would mold several test tabs right onto the framesheet and stress them to failure one at a time, adding more material (additional layers) as needed and where needed. When the sheet reached the target strength, I would then cut off any remaining tabs.

Eager Plastics, the Composite Store, John R. Sweet and West Marine are good sources. If you shop around, you can get enough epoxy for about $40. You will need other supplies such as gloves, epoxy measuring pumps ($15), auto repair squeegees.

[Moe Dog]

From my understanding, after speaking with a company that sells it, Aerogel ‘fabric’ is extremely dusty and must be encapsulated with some type of fabric or film. This requires some specialty equipment that most people would not own or have access to, however they offer this service and would use any fabric/film that you request/provide.

Areogel has fantastic insulation qualities per thickness, but is very heavy in comparison to other insulation per ounce. Down or synthetics are far lighter for the equivalent insulation ‘power’. (i.e. A 1/4″ thick Areogel blanket might have the same R-value as that of a 2″-lofting down comforter, but it would weigh several times more than the down comforter). Check the density: 8 lbs per cubic foot, then do the math.

But if you still want to buy the material, try these guys:

http://www.industrialinsulations.com

They sell Spaceloft 6200 for about $6.50 per sq FOOT with a minimum order of $500. (not sure if that includes encapsulation, or even the cost of the material to encapsulate with).

[J R]

Now, Jason, isnt Aerogel refered to as “solid smoke” due to the fact that it has almost ZERO weight and is the lightest non-gasseous substances on earth?

“Aerogel is the lightest and lowest-density solid known to exist. It is typically 50-99.5% air, yet can hold (theoretically) 500 to 4,000 times its weight in applied force. Aerogel can have surface areas ranging from 250 to 3,000 square meters per gram, meaning that a cubic inch (2.5 cm x 2.5 cm x 2.5 cm) of aerogel flattened-out (again theoretically) would have more surface area than an entire football field! Aerogel’s superlow density makes it useful as a lightweight structural material, and its superhigh internal surface area makes it a superinsulating solid material.” http://homepages.cae.wisc.edu/~aerogel/aboutaerogel.html

“Typically, aerogels are composed of 90-99.8% air, with densities ranging from 1.1 to around 150 mg/cm³” http://en.wikipedia.org/wiki/Aerogel

I dont see anything on that industrial insulations page that even resembles Aerogel.

[Denis Hazlewood]

David,
About a year ago I bought a Golite Trek. I loaded it and tightened the compression straps as tightly as I was able. When I put it on and tried to set the load lifters the top of the pack bent over instead of lifting the straps off my shoulders. The pack was just too flexible and no way could I get the load lifters to work properly. I examined the pack and thought I might be able to make a very light weight “frame board” to stiffen the pack.

Aluminum stays of my Mountainsmith pack were used as a pattern and I made a form of plywood and waxed cardboard. I used a yard of 3oz. carbon fiber cloth and a 2 part West System epoxy that I got at a ships chandlry. There are 3 layers of cloth as the base layer with extra layers to stiffen the top third.

Using the Trek’s foam panel as a pattern I cut the laminated board to shape and sanded the edges smooth. I then glued the foam to the carbon fiber panel. It took some research to find a glue that would work. I finally found Misty Heavy Duty Spray Adhesive that worked great. It’s made by AMREP of Marietta, GA.

I had to modify the Trek’s back panel pocket a little. A friend has a heavy duty sewing machine that came in handy.

The thing worked great and made the pack work for me. I did end up cutting some vertical slots in the lower quarter to allow the board to bend around my lower back.

The whole thing was easy and I believe anyone could do it. Difficulty on a scale of 1 to 5 = 3. Be sure to follow the epoxy mixing and application instructions exactly.

If you’d like to contact me try denis at oberkamper.com.

Good Luck

[Moe Dog]

JR, The stuff you’re referring to is the original Aerogel that is like styrofoam – inflexible, brittle, as in your quote: “structural material”, “solid material”.

But you had initally asked about a “flexible Aerogel BLANKET”. When they use the same technology in a FABRIC that IS flexible, it has extreme insulative properties but is also very dense – despite the fact that they call it ‘lightweight’. You can read about it here:

http://www.aerogel.com/products/overview.html
Click on the “Data Sheet” links.

And, you’re right, there is nothing on that website from Industial Insulations regarding Aerogel. However, they DO sell it, you just have to call them and ask.

Also see this thread (Richard Nisley makes the same point which is very well stated):

http://www.backpackinglight.com/cgi-bin/backpackinglight/xdpy/forum_thread/4243/index.html

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