Originally Posted by melgross
This is like fiberglass, it's almost impossible to recycle. But with fiberglass thay can grind it down for certain uses.
Also these carbon nanotubes used for some of the newest, most exotic stuff, which is expected to become much cheaper (it's mucho times more expensive than the stuff used for bikes and cases), is considered to be a health hazard.
That's why it's called FRP (Fiber Reinforced Plastic).
There is no such thing as production SWNT (Single Walled Nano Tubes).
Carbon fibers themselves have the worst compressive properties due to kink banding. That's why you don't see high modulus ropes made from carbon fibers, the carbon fibers break quite easily relative to Zylon (PBO), Kevlar/Twaron, Dyneema/Spectra, Technora, or Vectran. DuPont has yet to produce production quantities of their M5 fibers, and if so, will first be used exclusively in military applications.
Carbon fibers, or Kevlar make excellent structural panels once bonded with resin, however the specific strength and specific modulus are reduced significantly due to the resin and woven fabrics to less that a factor of two strength wise and will never be as stiff pound for pound as existing high strength metals. No existing high strength woven fibers can currently match steel with a modulus of 29,000 ksi, or aluminum with a modulus of 10,000 ksi, or titanium with a modulus of 16,000 ksi.
Some basics are in order, EI is the product of modulus and moment of inertia (bending), this produces the inherent bending stiffness of any material, similarly EA/L produces the inherent axial stiffness (or K). While high modulus fibers have high strength to weight ratios relative to metals, this is reduced significantly as noted above due to the necessary addition of resins and to woven fabrics with warp and weft fill components (the fibers no longer lie in a straight line, although unidirectional multiply laminates are always possible, say 6 plies at 60 degrees each).
For instance, structural panels use a very light weight foam core (PE, PU, PET, or PVC) bonded to high strength metals such as 7075-T6 or 6061-T6 aluminum or FRP panels. Also see the Airbus A-380 which used such a material patented as Glare (can't remember at this very moment if it's a foam core or an FRP core though).
Dyneema is a very poor material due to it's linear creep properties inherent in it's low temperature limitations (70 C max, 50 C for long lifetime). Dyneema is not 15 times stronger than high strength metals (A factor of 10 is the most I've ever seen the Dyneema literature claim), stainless steels can easily exceed ~250 ksi yield stress, aluminum ~80 ksi, and titanium ~200 ksi.
Apple has zero direct experience with FRP, the SME's would all be from other private sector industries. Anyone with half a brain can do metals, apparently Apple has at least half a brain (the Asians).