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A New Use for Kenaf

Kenaf, a reedlike crop that towers 12 to 15 feet, could offer a new source of insulation material for diminishing road noise in cars and other vehicles, an Agricultural Research Service scientist reports.

Kenaf is now mainly grown as an alternative source of fiber other than tree wood, and is used in low-grade paper, particle board, animal bedding, oil absorbents and other products. But ARS researcher Dharnidhar V. Parikh says kenaf fiber also can be made into lightweight insulation against road noise that penetrates door panels, dashboards, floor mats, package trays and other areas of a vehicle's interior. His observations are based on collaborative studies with Janesville Products, an auto insulation manufacturer in Norwalk, Ohio.

Currently, fiberglass, polyester and polypropylene rank among the top materials of choice for auto insulation. But kenaf holds the advantage of being a renewable resource derived from a domestic crop. Plus, it is lightweight, biodegradable and porous, which helps trap sound waves, notes Parikh, who heads the ARS Southern Regional Research Center's nonwovens research program in New Orleans.

There, Parikh devised a mechanical process for separating kenaf fiber from the stalk's bark and core before retting, a step that partially removes lignin, a natural resin, and makes the fiber soft and pliable. In Janesville Products tests, nonwoven fabric insulation containing kenaf fiber blocked sound waves at frequencies of 2,000 hertz, a range that meets auto industry needs.

According to Parikh, whose research aims to find new, value-added uses for fiber crops, other auto insulation candidates are jute, flax and cotton.

A more detailed article about his work appears in this month's issue of Agricultural Research magazine.

ARS is the U.S. Department of Agriculture's main, in-house research agency.