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A D V A N C E D M A T E R I A L S & P R O C E S S E S | F E B R U A R Y / M A R C H 2 0 2 1 8 METALS | POLYMERS | CERAMICS has multiple uses in the construction and automobile sectors as a sealant as well as a thermal and acoustic insulator. To date, castor oil has been one of the main candidates in the race to obtain sustainable polyurethane foam that does not require petroleum. One of the challenges is that this vegeta- ble-based oil does not offer complete hardness and dryness once exposed to air, one of the keys to proper rubber foam formation, according to research- ers. For this reason, the new research proposed substituting 50% of this cas- tor oil for wheat straw, with results that offer similar characteristics to those generated by traditional manufacturing processes that use nonrenewable com- pounds. “We were able to obtain very desirable parameters in the manufac- turing of foam, converting 96% of the wheat used with an almost maximum performance,” explain researchers. In addition, they obtained higher levels of biodegradability than those reached by the products currently on the market. After the wheat waste is liquefied, polyols are obtained. These polyols are one of the key compounds that play a Scientists measured the plastic deformation that occurred when a tiny probe exerted force on the micropillar specimens with various loading axis orientations. Courtesy of National Institute for Materials Science. HEAT-TOLERANT ALLOYS UNDER PRESSURE Scientists at Kyoto University in Japan are studying atomic-level mea- surements to develop more heat-toler- ant components in gas turbines. Metals containing niobium silicide are prom- ising materials that can withstand high temperatures and improve efficiency of power plant aircraft turbines, but it has been difficult to accurately determine their mechanical properties due to their complex crystal structures. The new microlevel approach could help scien- tists obtain the accurate measurements needed to understand the atomic-lev- el behavior of complex crystals under pressure. “Our results demonstrate the cut- ting edge of research into plastic defor- mation behavior in crystalline materi- als,” researcher Kyosuke Kishida says. In the work, scientists measured plastic deformation in a niobium silicide called α -Nb5Si3. Tiny micropillars of these crystals were exposed to very small amounts of stress using a machine with a flat-punch indent- er at its end. The stress was applied to different faces of the sample to determine where and how plastic deformation occurs within the crys- tal. By using scanning electron microscopy on the samples before and after the test, they were able to detect the planes and direc- tions in which deformation occurred. This was followed by simulation stud- ies based on theoretical calculations to further understand what was hap- pening at the atomic level. Finally, the team compared the results with those of a boron-containing molybdenum silicide they had previously examined. The team plans to use their approach to study mechanical properties of oth- er crystalline materials with complex structures. www.kyoto-u.ac.jp/en. REPURPOSING WHEAT FOR FOAMS University of Córdoba, Spain, re- searchers found a new way to repur- pose wheat straw by using it as the foundation to manufacture polyure- thane foams. Until now, this agricultur- al excess material had no well-defined use and produced exorbitant amounts of waste. Plastic “foam rubber” materi- al, often manufactured from petroleum by-products, is extremely versatile and Researchers from the DOE’s Oak Ridge National Laboratory, Tenn., used a blend of a self-healing polymer with curable elastomers to produce a series of self-healable and highly adhesive materials. The elastomers can self- repair in ambient temperatures and conditions, as well as underwater, with their adhesive force only minimally impacted by surface dust. ornl.org . BRIEF ORNL’s tough elastomers have uses in the automotive and electronics industries.