(JA) Scientist develops artificial timber

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Scientist develops artificial timber

 

May 15, 2001

Satoshi Yamada Yomiuri Shimbun Staff Writer

 

The lumber industry has long been examining ways to create suitable timber

substitutes as part of efforts to promote recycling in the society. A

scientist at Mie University in Mie Prefecture is currently working on the

final stages of developing artificial timber after having discovered a way

to extract lignin, a strong adhesive substance, from natural wood.

 

The first step in producing the artificial material is to extract and mold

fibers from waste paper or scrap wood, to which lignin is added. It is

expected that the material will be able to be recycled repeatedly.

 

Within a few years, it may become possible to use the material to

manufacture furniture similar to that now made from plastic. The material

might also have applications at the international space station, where there

is a strong need for recyclable supplies and materials.

 

Masamitsu Funaoka, a professor at Mie University's bioresources department,

explained the composition of the artificial wood. & quot;The new material is

created only with components initially dissolved from natural timber, & quot;

he said.

 

The new material resembles fine-grained natural wood and creates a crisp

sound when tapped. It looks similar to concrete stakes produced to resemble

wood that are often seen in parks. One of the main ways the material differs

from natural wood is in the absence of annual rings.

 

Fiber, such as cellulose, is the main component of wood. Lignin is an

amorphous polymer with a rough surface that wraps around fibers to solidify

them. Lignin accounts for 20 percent to 30 percent of timber content.

 

In the production of artificial wood, lignin is extracted from scrap wood

and shavings and added to fibers from waste paper. In doing so, the material

becomes very affordable, as its components are inexpensive and almost

inexhaustible.

 

The production process is simple. Paper is dissolved in water and dried, and

the fibers are mixed with lignin and left to solidify. Like natural trees,

this artificial wood can decompose with the help of microbes.

 

The strength of the artificial material is determined by the amount of

chemical processing that occurs during its production. According to Funaoka,

the artificial material is actually stronger than natural wood.

 

Another advantage is the ability to form the material into desired shapes.

Even after it solidifies, the material can be returned to its original

fiber-and-lignin state by submerging it in an alcohol-based solution.

 

Funaoka said artificial timber is a particularly efficient product due to

its simple production process and the fact that it can be recycled

repeatedly.

 

However, the use of lignin in the new material brings up the question of why

such a versatile substance had not been used until recently.

 

While it was long known that lignin was a strong adhesive, no one had yet

discovered a way to extract it from wood while preserving its adhesive

properties. It was generally viewed as an unwanted by-product by paper

manufacturers, who would remove it by submerging wood in a strong alkaline

solution and heating it to 170 C. This process would remove the lignin, but

would warp it's vital net-like structure.

 

To extract the substance without changing its structure, Funaoka paid

special attention to differences in how lignin and fibers reacted when

exposed to water. He found that lignin is hydrophobic, meaning it repels

water, while fiber is hydrophilic, meaning it adheres to water.

 

According to Funaoka, the first step in extracting lignin without altering

its original state is to submerge wood in an organic solvent containing

phenol to coat the substance. An acid solution, such as sulfuric acid, is

then added to dissolve fibers and separate lignin from the wood.

 

Funaoka says that after 20 years of research, the development of artificial

wood is in its final stages. Full-scale research into the material's

production began at the start of this fiscal year. In August, university

experimental facilities costing about 100 million yen will be completed

after the project receives approval from the Education, Science and

Technology Ministry.

 

Also, about 20 companies from around the country have formed an association

to support recycling technologies. The association has received subsidies

from the Forestry Agency and recently launched a five-year research project

into the issue.

 

& quot;By using (recycling technology), it is possible to use wood over and

over by changing its shape, & quot; Funaoka said.

 

Copyright The Yomiuri Shimbun