3 ms·

> it's the epoxy resin it's been filled with that's tougher, right? Your comment seems to suggest that the cellulose left after removing the lignin from the wo

by KMag 3y ago

> it's the epoxy resin it's been filled with that's tougher, right? Your comment seems to suggest that the cellulose left after removing the lignin from the wood isn't playing any role. The wood really is playing an integral role. It's the epoxy reinforced with the cellulose remaining after lignin removal that's tougher. Just a block of cured epoxy resin isn't going to be tougher than glass. It's a similar case with "carbon fiber" items. If you just wrapped a pressure vessel with carbon fiber, it really wouldn't help much. It's the carbon fiber reinforced resin that's strong. That tennis racket wouldn't work very well with just carbon fiber or just epoxy resin.

chongli 3y ago
Yeah, same goes for reinforced concrete. Just concrete or just rebar isn't going to work nearly as well. It's the two combined that provide the powerful combination of compressive strength and tensile strength. This is the whole rationale behind composite materials: combining different materials with different properties to obtain a gestalt material.
tomn 3y ago
> Just a block of cured epoxy resin isn't going to be tougher than glass. I wouldn't be so sure -- toughness has a specific meaning (energy before fracturing), and polymers are generally going to be tougher than glass. http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/strength-toughness/basic.html http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts... I haven't dug into it, but note how the article mixes up these terms to make it sound better: > transparent wood came out around three times stronger than transparent plastics like Plexiglass and about 10 times tougher than glass. If you plot that on those graphs it doesn't put it anywhere remarkable. edit: This is like trying to sell an electric bike by saying that it's three times faster than walking and 1/10 the price of a car -- ok, but how does it compare to a pedal bike? It's much more obvious when you do it with words that most people understand intuitively.

by KMag 3y ago

chongli 3y ago

Yeah, same goes for reinforced concrete. Just concrete or just rebar isn't going to work nearly as well. It's the two combined that provide the powerful combination of compressive strength and tensile strength. This is the whole rationale behind composite materials: combining different materials with different properties to obtain a gestalt material.

tomn 3y ago

> Just a block of cured epoxy resin isn't going to be tougher than glass. I wouldn't be so sure -- toughness has a specific meaning (energy before fracturing), and polymers are generally going to be tougher than glass. http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/strength-toughness/basic.html http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts... I haven't dug into it, but note how the article mixes up these terms to make it sound better: > transparent wood came out around three times stronger than transparent plastics like Plexiglass and about 10 times tougher than glass. If you plot that on those graphs it doesn't put it anywhere remarkable. edit: This is like trying to sell an electric bike by saying that it's three times faster than walking and 1/10 the price of a car -- ok, but how does it compare to a pedal bike? It's much more obvious when you do it with words that most people understand intuitively.