Chinese scientists have created a polymer synthetic wood, which, by its chemical composition and the microstructure resembles a real, but has a greater fire resistance and can better withstand exposure to water and acid, according to a paper published in the journal Science Advances.
Wood remains one of the most common structural materials due to availability and favorable combination of relatively high strength, low density and thermal conductivity. Scientists have been trying to create materials with similar properties on the basis of wood or other materials.
A group of scientists led by Shu-Hong Yu (Shu-Hong Yu) from Kefayskoy national laboratory for physical Sciences at micro-scale has created a material of a different composition but with similar structure. As an alternative to lignin in this tree, scientists used retornou resin, which has a similar polyphenolic structure. In addition, the researchers used alternatively resolveu resin melamineformaldehyde resin.
For the manufacture of artificial wood creates a water solution to which is added one of the two resins, a small amount of chitosan and acetic acid. The solution is placed in a mold with the bottom copper plate that was cooled with liquid nitrogen. Because of this, the solution freezes and during the solidification is the process of self-organization of polymers in the matrix of elongated channels, the same ligninov matrix in the wood. After the formation of the block of ice and the polymeric matrix it is placed in the apparatus for vacuum drying, which removes water, and then heated to a temperature not exceeding 200 degrees Celsius, whereby the matrix is completely solidified.
Research with a scanning electron microscope showed that the resulting material resembles in its structure the wood. The thickness of the matrix is 3-5 micrometers, and the width of tubes to several tens of micrometers. The experiments showed that these parameters depend on the concentration of the polymer in the initial solution, cooling rate and temperature of solidification of the polymer. In addition to “pure” synthetic wood scientists have also created composites with the addition of other materials, such as graphene oxide, and the oxide and silicon carbide.
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Scientists have tested the properties of the synthetic wood and compared them with the present. For some compositions, the limit of compressive strength was equal to 45 megapascals, which is comparable with some of this wood. However, the modulus of elasticity of such material is up to 700 megapascals, which is about a order of magnitude less than typical values for wood. Also the experiments showed that the monthly aging of the material in water or sulfuric acid reduces its mechanical properties, but not as much as the properties of balsa wood, which performed a similar experiment. In addition, tests have shown that the artificial material has a comparable thermal conductivity, but more fire-resistant.
The Koz Times,2018-8-11,https://koztimes.com/scientists-have-created-a-wood-with-amazing-properties/3406/