In materials science texts, I see wood used an example of a naturally occurring composite material. One of the main components of wood is cellulose, which is a polymer. But what other component makes it a composite?
Thanks for any clarification.
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1$\begingroup$ This question is answered in the 2nd sentence of the Wikipedia article on wood. $\endgroup$– The PhotonMar 10, 2019 at 20:11
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$\begingroup$ @ThePhoton Perhaps I misunderstood the definition of composite. Is a material with two types of polymers considered a composite? Or must it the material contain a type of polymer with a type of ceramic and/or metal? My understanding is that lignin and cellulose are both polymers. $\endgroup$– The PointerMar 10, 2019 at 20:15
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$\begingroup$ If this is for a class, that might depend on exactly what definition is given in your class. Wikipedia just says the component materials should have "significantly different physical or chemical properties". $\endgroup$– The PhotonMar 10, 2019 at 20:37
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$\begingroup$ @ThePhoton I'm reading the textbook Materials Science and Engineering by William Callister and David Rethwisch. It says the following: A composite is composed of two (or more) individual materials that come from the categories previously discussed -- metals, ceramics, and polymers. I thought that meant that the material must be at least from 2 of those 3 categories, but I might have interpreted it incorrectly? It might mean that it can be 2 polymers, 2 metals, 2 ceramics, etc.? $\endgroup$– The PointerMar 10, 2019 at 20:40
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2$\begingroup$ No, all of the components can belong to the same 'category' (e.g. metal-metal composites). $\endgroup$– lemonMar 10, 2019 at 20:42
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the two components of wood-as-a-composite are cellulose fibers and lignin, the resin in which the cellulose fibers are embedded. Cellulose furnishes strength in tension and the resin furnishes strength in shear.
answered Mar 10, 2019 at 20:57