TRANSPARENT WOOD AS A BUILDING MATERIAL

HISTORY OF TRANSPARENT WOOD

For the first time, transparent wood was created in the year 1992 by a German scientist Siegfried Fink. A research group by two Professor Lars Berglund from Swedish KTH University and Professor Liangbing Hu from the Maryland University has developed a technique to remove the color and different chemicals from the wooden piece, possible by adding polymers like Poly (methyl methacrylate) and epoxy, at the cellular level, thereby rendering them transparent in the 2015-2016 year.

THE MANUFACTURING PROCESS OF TRANSPARENT WOOD

 

In its natural state, wood is not a transparent material because of its properties like scattering and absorption of light. The tannish color in wood is due to its chemical components of the polymer composition of cellulose, hemicellulose, and lignin. The wood's lignin is drastically responsible for it's distinctive or brownish color. The amount of lignin determines by the levels of visibility in the wood, around 80-95%. To make wood a visible and transparent, both absorption and scattering need to be reduced in its product creation. The manufacturing process of this type of wood is based on removing all the lignin called the delignification procedure.

It is produced by treating and compressing the wooden strips. The normal way to manufacture transparent wood is to take a piece of the wooden block and place it in a bath of boiled water, Sodium hydroxide, and Sodium sulfite. The next step is to just let it remain soaked there for about 12 hours. This procedure strips away all the opaque stuff and leaves behind floppy transparent structural cellulose.

Once you get rid of all the cellulose, sink the wooden piece into a bath of hydrogen peroxide which will further bleach it a little more. Both these steps are apparently the standard method used to create paper thereby making it look smooth and white. This process leaves behind bone-white wood fibers. The wood looks crunchy after the process since the lignin is “nature’s glue”.

The final step is to transfer all the cellulose and bubble epoxy in a vacuum chamber. Wood is basically put under a vacuum and is later smothered with clear epoxy. The tubes that are made of wood fibers soak up the epoxy resin. When it dries up transparent wood is obtained. Wood grains are even visible on it, but it is incredibly tough.

ADVANTAGES OF TRANSPARENT WOOD

1) One of the major Pros of transparent wood in the comparison of the typical glass its structural properties like ductility and resistance to fracture is higher. It is almost transparent as a glass but it has higher strength compare with any glass.

2) It is a better biodegradable material in comparison with any plastic.

3) It can be used to create highly strong and energy-efficient windows.

4) According to ‘D. Katunsky’ et. al. (Structural Elements with Transparent Wood in Architecture), transparent wood sets the path for greener architecture and better electronics.

DISADVANTAGE OF TRANSPARENT WOOD

The only drawback that can be pointed out with this type of wood is; the epoxy isn’t environmental or eco- friendly. Currently, it is only possible to make it in the labs. But the engineers are very confident that soon they will be able to replace the epoxy with recyclable plastic and scale the procedure. It means that in the future the buildings partly made with transparent wood shall be dominant.

APPLICATION OF TRANSPARENT WOOD

1) Transparent wood roofs can be designed to some of the buildings for providing uniform and comfortable illumination as compared to any conventional glass.

2) In addition, Panels can be built from this type of wood which exhibits lower thermal conductivity, better impact strength, and lower density as compared to any glass.

3) Functionalized transparent wood provides even better opportunities for smart buildings. By the inclusion of quantum dots, transparent wood attains diffused luminescence properties. It can be used in planar light sources, luminescent building components, or designed furniture.

4) In order to provide electromagnetic interference shielding to the transparent wood, magnetic nanoparticles have been incorporated into it.

5) Another important application of transparent wood is; it is used as a structural material for some of the photovoltaic devices such as electrochromic devices and solar cells. Because of the high haze, transparent wood can be designed as a light-diffusing layer. Furthermore, high haze means large scattering angles, which increase the length of the light path inside solar cells, so that efficiency is improved.

6) The devices exhibit a vibrant magenta-to-clear color change with a high coloration efficiency and low driving voltage. This entire concept will contribute to smart windows, which in turn saves energy.

7) Transparent wood can be used on façades in cases where there is a requirement for sunlight to illuminate the interior, but privacy is equally important. It is because of the high values of optical haze in transparent wood, which lets the light in, but clouds the view; it can be used for those peculiar cases.

CONCLUSION

Transparent wood is a very important topic in the emerging field of wood nanotechnology – both in the academics and in the industrial field. Noticeable progress has been made which includes manufacturing of this wood with improved all mechanical properties, producing large & thicker transparent wood structures, along with the realization of this type of wood fictionalization. In-depth of study is required to understand the light–wood interaction to tune the optical properties and mechanical properties, improve the green aspect and to explore advanced transparent wood applications and uses.

Transparent wood is a newly invented material. Currently, it is a topic of research and undergoing various experiments, but it certainly holds great potential for becoming an important building material. Its translucency along with its outstanding mechanical properties is making it an interesting choice for using in façades and for that fact, it is gradually paving its way towards being listed as a structural material in the field of construction.