Engineered Superwood Stronger Than Steel

Engineered Superwood Stronger Than Steel Researchers at the University of Maryland are transforming wood by modifying its cellular structure. They’ve made it squishy and bouncy like rubber, transparent like glass, and as strong as steel and titanium alloys. Since 2013, Dr. Liangbing Hu’s lab has been reengineering wood at the nanoscale. The researchers utilize various chemical, mechanical and thermo technologies to create the new types of wood. Hu started working with wood after noticing the similarities between cellulose nanofibers and carbon nanotubes. In fact, the cellulose nanocrystal is stronger than a carbon fiber. A key difference is the lower cost and sustainability of wood compared to lab-produced carbon fiber. Over the next several years, he modified the wood to create transparent paper and a glass-like material. He also developed a type of wood that was flexible and could bounce like a Superball. The version of wood that has attracted the most attention is Superwood. It’s five times thinner but has four times the density of regular wood. It’s 4 to 20 times stronger and stiffer, with 3 to 10 times higher dent resistance. It boasts 50% greater tensile strength than steel and has 10 times the strength-to-weight ratio. Superwood offers excellent UV and weather resistance and experiences minimal dimensional changes, such as swelling and warping. Exterior-grade Superwood withstands freeze-thaw cycles and temperature fluctuations. It has a Class A fire rating, is resistant to moisture, termites and fungi, and has even demonstrated bullet resistance. In one test, a bullet penetrated through untreated wood but lodged halfway through a same-sized block of Superwood. To produce it, Hu uses food-grade chemicals to modify lignin and selectively remove hemicellulose, then applies heat and pressure. This causes the wood’s structure to collapse and the cellulose fibers to realign, forming new chemical bonds.  Hu licensed Superwood to InventWood. This summer, the company began commercial production of interior finishing materials using woodchips as the cellulose source. This fall, InventWood plans to introduce exterior-grade panels for siding and roofing. In the next few years, the company aims to begin producing structural beams and columns. That’s only awaiting certification. You don’t need special tools to work with Superwood. Regular woodworking tools work well, although its density might call for slightly different techniques. Like wood, it can be treated with most standard finishes. Superwood’s initial pricing is described as competitive with high-quality tropical hardwoods and hybrid woods, such as wood fiber composites, steel or concrete. Although it’s much more expensive than steel on a pound-for-pound basis, other factors are important. The 10-fold higher strength-to-weight ratio means a 10-lb. Superwood beam can match the load capacity of a 100-lb. steel beam. This can bring the effective cost closer to steel. As production increases and costs decrease, the price difference will narrow. Contact: FARM SHOW Followup, InventWood, Frederick, Maryland (www.inventwood.com).

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