Eovations's mineral/thermoplastic composite has a modulus of elasticity between 500,000 psi and 800,000 psi, but a modulus of rupture of zero. It can flex extremely well, but does not have a catastrophic failure mode. (Source: Eovations)
Ann, this is an interesting material. It is impressive that it can be used like wood, using the same tools and fasteners. That should make acceptance easier. The hurricane resistance should be of much interest in areas where that is a problem. I know someone with a place in Florida, and although the structure is concrete and quite resistant, they had to replace windows with bullet proof ones. Other structures, those with conventional roofs, are a real problem. This material would help.
Okay, I'm pretty sure that "the modulus of rupture is zero" is not a correct statement. "Modulus of rupture" is a measure of the load-carrying capacity of a beam. A material with a load-carrying capacity of zero would not be very useful.
The modulus of rupture formula is only correct up to the elastic limit, so presumably the meaning of the statement is that it yields before it breaks. That's also how I'd interpret the rather amazing statement that "it does not have a catastrophic failure mode." If it doesn't fracture under any circumstances, it's be a miracle material, and they should be contacting physics journals rather than Design News. But I think they are just saying that it yields before it breaks.
That being said, this sounds like a pretty neat material. Mineral-filled polypropylene is a fairly common (and reliable) engineering material. However, making it into an open-cell foam, and drawing it so that the polymer chains are oriented, is an interesting innovation.
Which is worse for the environment, manufacturing these composite materials or logging the equivelent amount of wood?
I like the idea of composite bridges and buildings though. Perhaps people would not have lost that much with Hurricanes Katrina or Sandy. I'm sure the current cost differences will keep the materials out of construction for years to come.
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?
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.
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?
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.
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?
What makes this movie stand out from the typical high school sports story is that the teenagers are undocumented immigrants, and the big game is a NASA-sponsored marine robotics competition. Like many other Hollywood movies, however, Spare Parts only tells part of the story. What the film shows -- and doesn’t show -- raises important issues affecting STEM education in the US.
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