Wood Pulp Extract Stronger Than Carbon Fiber Or Kevlar 208
Zothecula writes "The Forest Products Laboratory of the US Forest Service has opened a US$1.7 million pilot plant for the production of cellulose nanocrystals (CNC) from wood by-products materials such as wood chips and sawdust. Prepared properly, CNCs are stronger and stiffer than Kevlar or carbon fibers, so that putting CNC into composite materials results in high strength, low weight products. In addition, the cost of CNCs is less than ten percent of the cost of Kevlar fiber or carbon fiber. These qualities have attracted the interest of the military for use in lightweight armor and ballistic glass (CNCs are transparent), as well as companies in the automotive, aerospace, electronics, consumer products, and medical industries."
Wood armor (Score:5, Informative)
Wood armor - we're back to the medieval days!
As with most (all?) engineered wood products - what about when it gets wet?
From TFA:
Swelling introduces a large number of nano-defects in the cellulose structure. Although there is little swelling of a single CNC, water can penetrate into amorphous cellulose with ease, pushing apart the individual cellulose molecules in those regions. In addition, the bonds and interfaces between neighboring CNC will be disrupted, thereby significantly reducing the strength of any material reinforced with CNCs. To make matters worse, water can move easily over the surface/interfaces of the CNCs, thereby allowing water to penetrate far into a composite containing CNCs.
They suggest painting it. To be honest, I'm a skeptic. We wore body armor during my time in Iraq, and the abuse that our gear received cannot be overstated. Rain, heat, jumping over walls, dealing with mud. No thanks, I'll stick with Kevlar.
Comparisons (Score:5, Informative)
Material, Elastic Modulus, Tensile Strength
CNC, 150 GPa, 7.5 GPa
Kevlar 49, 125 GPa, 3.5 GPa
Carbon fiber, 150 GPa, 3.5 GPa
Carbon nanotubes, 300 GPa, 20 GPa
So a great compromise material when you take cost into account, if it comes to fruition.
Re:Cheaper & Stronger than Carbon Fiber? (Score:4, Informative)
The vulnerability to moisture makes it unsuitable for use in street vehicles unless stringent safety regulations are backed by frequent inspection. It would be dandy for high-end race vehicles, though.
Re:Comparisons (Score:3, Informative)
I'll correct myself then.
Tensile strength should be in MPa. Those figures are all correctly adjusted but the Carbon Fibre ones are again wrong.
Typical figures are from as low as 0.25 GPa all the way up to 7.1 GPa.