transparent material - online puzzles

Transparent wood composites are novel wood materials which have up to 90% transparency and higher mechanical properties than wood itself, made for the first time in 1992.

When these materials are commercially available, a significant benefit is expected due to their inherent biodegradable properties since it is wood. These materials are significantly more biodegradable than glass and plastics.. Transparent wood it is also shatterproof. On the other hand, concerns may be relevant due to the use of non-biodegradable plastics for long lasting purpose, such as in building.

History

A research group led by Professor Lars Berglund from Swedish KTH University along with a University of Maryland research group led by Professor Liangbing Hu have developed a method to remove the color and some chemicals from small blocks of wood, followed by adding polymers, such as Poly(methyl methacrylate) and epoxy, at the cellular level, thereby rendering them transparent.

As soon as released in between 2015 and 2016, see-through wood had a large press reaction, with articles in ScienceDaily, Wired, the Wall Street Journal, the New York Times, to name a few.

Actually those research groups rediscovered a work from Siegfried Fink, a German Researcher, from as early as 1992: with a process very similar to Berglund's and Hu's, the German Researcher turned wood transparent to reveal specific cavities of the wood structure for analytical purpose.

The process

Transparent wood was made based on the idea of removing light -absorbing components (mainly lignin) followed by infiltration of a polymer with a refractive index matching the wood substrate.

One example is a three step process:

The first step consists of immersing the 4 or 5 inch block of wood in a solution of water, sodium hydroxide, and sodium sulfite at boiling temperature for two hours.