Ann, I wasn't talking about plastic trees; I was thinking about the renewable feedstocks we'd discussed several months ago. You mentioned that such feedstocks are no longer food-based such as corn, but still organic based.
Dave, the absence of a catastrophic failure mode (the modulus of rupture is zero) typically doesn't mean the material doesn't fail: it means it doesn't fail catastrophically, or, it bends before it breaks as you said. TJ, I agree about your comparison with plastic--anyone planted any plastic trees lately?
"Which is worse for the environment, manufacturing these composite materials or logging the equivelent amount of wood?"
Logging industry is careful to point out the renewable resource that is lumber, and that they plant a large number of trees every year to replace what was cut. I don't think it's as easy to make that statement with regard to polypropylene.
I think it's certainly commendable a company is looking at prospects of recycling what would otherwise be waste materials into a usable product. I do agree that if the material is to be used for building purposes, flammability, tensile and compression strength, rupture strength and mold retention could be problems. Fortunately, these are characteristics that can be tested for and quantified. One question I have, do we know if there are UL standards that govern the usage of products such as these?
The article stated the pores are closed cells but create open space between the fibers. I interpret this as closed cell foam which could perhaps be used in floating applications. Trex is pretty heavy and floppy (and expensive) but weathers better than wood. At the same price as Trex, this would seem to offer some attractive advantages. I wonder the size of the pores as cut edges would expose them. Perhaps they could be "ironed" to smooth them or even textured with heat. You may also be able to form them into hollow structural members to gain stiffness without weight (steel i-beams do this, a web with flanges on the top / bottom, or rectangular tubing (some plastic decking is formed like this). Enough mineral filler or water releasing filler (i.e. alumina tri-hydrate) might help improve fire resistance.
1. Universal Forest Products is behind this. They sell lumber and engineered lumber products. Are they researching less expensive alternatives? Better performing doesn't matter if there is not a cost savings.
2. Price same as building composites already on the market.
In my industry we saw a breif excited period of composites being used in commercial buildings (residential is a different market). This period has past with more use of conventional wood products and fiber cement sidings and trim. The choice always comes down to cost. Even in fire rated construction heavy timber remains an option where milk jug lumber may not be used. The timber industry is sustainable and the total energy used to mill and transport timber is less than the energy required to create synthetic lumber. So will this product become something more than a competitor for Trex when we don't even use Trex now?
A material thyat bends instead of breaking will have uses, but not the same as for some of the more common materials, unless it is also adequately stiff to begin with. One immediate application would be as a decking material for bridges, where the ability to flex with an overload would be very useful. Likewise for stair step tops, which get damage from varied kinds of abuse. In fact it would probably be useful for any application that had only intermittant loading.
I would offer a concern about the porous structure possibly allowing the penetration of a variety of undesireable elements including molds and asorted contamination. But possibly the spaces are small enough that it would not be much of an issue.
The report did not mention anything about flamability, which could also wind up being a show-stopper concern. Perhaps that information is available for addition to the writeup.
The modulus of elasticity is about one-third that of Douglas fir, so I don't imagine it could be a one-to-one replacement for wood in critical structural components, such as bridge beams. So does anyone know which wood components might be replaced using this material?
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