Although fiber reinforced polymer (FRP) has multiple advantages as an architectural material, there are issues with sustainability. The polymers are made from petroleum, a dwindling and non-renewable resource with significant environmental impacts from both extraction and transportation. The process of making it into resin has its own carbon footprint, as do the processes for making glass fiber and carbon fiber. (Carbon fiber is also made from petroleum.)
That situation could be changing. Last week we looked at bio-composites currently being developed at North Dakota State University. This week, we look at bio-based resins that are commercially available right now.
Entropy Resins, of Hayward, CA, was founded by two brothers from the Bay Area, Rey and Desi Banatao. Desi studied engineering and material science, Rey is a biochemist. As Rey puts it, “At one point we decided, why are we working on everyone else’s dumb ideas when we could work on our own dumb ideas?” Both were working in nano-materials (Desi at UC Berkley, Rey at the California Nanosystems Institute at UCLA). Their first idea was to use carbon nanotubes in composites, which they developed and published with the help of Bayer Sciences.
Then they started making things in the Sporting Goods realm. “We’re outdoors guys, and we thought it was fun to make the materials into surfboards, snowboards, skis…” They were contacted by a famous surfer, Laird Hamilton, who wanted to make boards out of bio-based materials. The Banatao brothers saw what the market had, and thought it could be improved. That was the birth of Entropy. (They later spun off another company, Connorra Technologies, to develop recyclable composites, which we will be spotlighting in the coming weeks.)
Desi Banatao is CEO of Entropy. The company offers several resins in their Super Sap family with different features of strength, clarity or color suitable to different applications, and varying degrees of renewable content. The resins are specialized for purposes including not only several methods of composite production, but also for coatings on other materials, and as adhesives.
The resins are all designed to equal or outperform the petro-based resins used for similar applications. “You can’t lose performance for any reason,” declatres Desi. He explains that his epoxy polymer is chemically like any other epoxy molecule. “We’re trying to create a molecule that would be chemically indistinguishable from a petro-based epoxy. But bio-based materials come into play. Instead of using petroluem, we’re using a start material that comes as a waste product. The main source is a waste product of bio-based fuel production, bio diesel. But it can vary based on geographies, commodity markets, etc.” The bio-diesel can be made from a variety of sources. In the US and Europe, vegetable oils that are not food grade, or are waste oil, used cooking oil, are often sources.
Their resin with the highest renewable content is 37% bio-based. They measure it in accordance with ASTM D6866, a method akin to radioactive carbon dating. (Since the advent of nuclear weapons, carbon on the earth’s surface is radioactively distinguishable from carbon originating in ancient plant life, such as petroleum.)
Moreover, Desi points out, they have lowered the carbon footprint from processing the raw material into epoxy resin by 33%. This is another important sustainable aspect of their products.
Entropy resins are compatible with any reinforcement fiber that is sized for use with petro-based epoxy. This potentially includes natural fibers, which would increase the renewable content of the composite. “The real problem with natural fibers,” explains Desi, “is that they usually come out of the textile industry, where you don’t want things to stick to it. The way they process materials for clothing makes the material difficult to bond to. One guy said to us, ‘We have to coat everything with PVA.’ In the resin world, PVA is a release agent. The bonding to raw fibers is mostly pretty good, because they are largely hollow.”
As to cost, Desi says they are competitive with petro-based resins up to container-quantities. At tanker-level quantities, petro-based resins are still cheaper.
Buildings are among the biggest things that humans build. Constructing them with rapidly renewable resources would be a wise move. The only major renewable construction material is wood. It is not rapidly renewable, and demand is outrunning growth. As composites emerge further into the architectural sphere, despite strong headwinds, using rapidly renewable resources with a lower carbon footprint would significantly alter the impact of construction on the planet.
Entropy’s resins do not have as high renewable content as the experimental resins being developed at North Dakota State University, but Entropy Super Sap is available right now.
Images courtesy of Entropy Resins