Submitted to: Textile Research Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2007
Publication Date: 5/15/2007
Citation: Parikh, D.V., Chen, Y. 2007. Reducing automotive interior noise with natural fiber nonwoven fiber covering systems. Textile Research Journal. 76(11). p. 813-820.
Interpretive Summary: The problem of adequately shielding automobile passengers from engine noise and random outside noise is high on the priority list for automobile manufacturers. The ability to reduce the amount of noise entering the passenger compartment of automobiles offers a competitive advantage to manufacturers. This study attempts to develop and quantify the sound absorbing properties of efficient natural fiber based noise absorbing materials made with kenaf, jute, flax and cotton in blends with polypropylene. The testing results demonstrate that each of the cellulose-based nonwoven composites have greatly improved sound absorbing properties that are comparable to the materials currently used in automobile interiors. Although there is increased efficiency in noise reduction with these materials, the individual acoustic characteristics of various vehicles determine the type and amount of material required. The noise reduction was significantly improved with the use of either of the underpads (cotton or polyurethane foam), however, the best noise reduction occurred with the use of a polyurethane underpad. Use of these natural materials (floor covering systems) will provide automobile passengers with a more quiet, safer environment (relatively biodegradable interiors) at a reduced cost compared to materials currently in use in the industry. Additionally, the weight of the vehicle (kenaf's fiber density is 1.40 vs. 2.55 for glass) is reduced. Hence, greater gas mileage for the vehicle is attainable.
Technical Abstract: It is important to automobile manufacturers to eliminate unwanted noise in passenger compartments of vehicles. The ability to reduce noise inside the vehicle enhances the perceived value of the vehicle to the consumer. Several methods to reduce noise and its sources are presently employed. One of the methods to make passenger compartments free from noise is to use sound absorbing materials such as floor coverings, package trays, door panels and luggage compartments in auto interiors. Natural fibers are noise absorbing materials that are renewable and biodegradable. Floor coverings using natural fibers (kenaf, jute, waste cotton, and flax) in blends with polypropylene (PP) and polyester (PET) were developed as carded needlepunched nonwovens. The acoustic properties of these floor coverings, used either alone or in combination with (a) a rebonded polyurethane foam underpad or (b) a soft cotton nonwoven underpad, were test evaluated by ASTM E 1050 "Impedance and Absorption of Acoustical Materials Using A Tube, Two Microphones and Digital Frequency Analysis System." The measurements demonstrated that each of the natural fiber based nonwoven floor coverings contributed to noise reduction. The noise reduction was significantly improved with the floor covering system using either of the underpads, however, the best noise reduction occurred with the use of a polyurethane underpad.