Going Green: The Practical Payoffs Of Kenaf
A plant that grows quickly and cheaply in Texas may become an alternative to building materials that are non-biodegradable, and may someday change the way businesses like Brown's Boat Repair in Mesquite operate.
Workers peeling off a damaged keel guard from the belly of a boat at the repair shop will replace the gouged-out area with thin, cloth-like layers of woven fiberglass and epoxy. Business owner Terry Brown says fiberglass is the material of choice for restoring a boat’s structure.
Brown: Very, very strong, durable, long-lasting. It does not ever deteriorate. That’s the neat thing about fiberglass.
As landfills near capacity that’s also one of the challenges. Fiberglass found in automobiles, insulation and numerous building materials doesn’t break down for hundreds of years. Brown says another problem is that fiberglass cracks or breaks.
Brown: Oh it’s very breakable. That’s why I’m in business.
Those factors are why scientists at the University of North Texas became very excited when they discovered a plant that may provide an alternative.
D’Souza: This is very close to fiberglass.
Professor Nandika D’Souza holds up a small square that looks like hard plastic encasing threadlike fibers. The fibers come from the bark of kenaf, a woody plant in the Hibiscus family. Kenaf can grow more than 10 feet tall in three to four months while using very little water.
In India, Bangladesh and southern Asia kenaf fiber is used to make cloth and rope. Its leaves are used for food. But Professor D’ Souza is an engineer in UNT’s material sciences department. So, when a West Texas farmer brought her a sample she naturally wondered if you could use kenaf to build things.
D’Souza: He thought the stalk is made out of fiber and maybe the stalk has value as some kind of a reinforcement or plant feed.
Her excitement grew as she examined the spongy structure of kenaf bark under a microscope. She realized you might be able to create a strong, lightweight material that wouldn’t be as breakable as fiberglass.
D’Souza: My whole life I’d been looking at glass fiber and graphite that wasn’t porous. I suddenly thought, “Oh my gosh, this probably solves the problem we’ve been searching for a solution for.” What happens is kenaf or any natural material because it’s transporting water or nutrients have a natural porosity and because of its porous it essentially acts like a sound absorber so it transmits the energy but doesn’t break.
Dr. D’Souza also liked the idea of using a renewable resource.
D’Souza: Fiberglass contains a lot of glass fiber and in the manufacture of glass fiber there is significant pollution as well as utilizing mineral resources that can never be returned.
With the help of a $600,000 National Science Foundation grant and colleagues in UNT’s biology department, Professor D’Souza began tackling practical problems.
After two weeks of soaking in pond water the fibers of kenaf bark become soft and silky, similar in appearance to glass fibers. But to create a steady supply for manufacturers that process known as retting would have to happen faster.
Allen: That’s not magic to me. That’s microbiology.
Microbiologist Michael Allen had a plan. He used a DNA sequencer to identify specific bacteria in the pond water. Then he grew them in large numbers.
Allen: We’ve been able to isolate a number of different strains that produce enzymes that cut the glue that holds these fibers together. And growing those up in large numbers we’ve been able to inoculate them into tanks and cut the retting time from two weeks down to three or four days.
Now Professor Allen is working to further speed up the retting process and test larger quantities of kenaf. Professor D’Souza’s lab assistants are weaving and blending the fibers with epoxy to create fiberglass-like products that are more flexible.
D’Souza: I think what I’m hoping through this is to have structures that are able to be made from renewable resources.
The UNT scientists believe their green research will have a practical payoff. They expect building materials made with kenaf to be on the market in three to five years.