There is considerable potential for use of vegetable fibers such as kenaf, jute, flax, and cotton (cotton fines, waste fiber) in moldable thermoplastics for automotive applications. The composites of these fibers have high tensile and flexural properties, coupled with economic and environmental benefits. Needlepunched nonwoven fabrics were produced using refined kenaf fibers and other vegetable fibers in intimate blend with recycled polyester, and polypropylene (PP) in weight percent ratio of 35:35:30. Composites in the ratio of 35:35:30 were also produced on spunbonded polyester scrim. Composites of vegetable fibers with PP in the weight ratio of 50:50 were also produced.

The thermal conductivity of the nonwoven composites were determined by a steady-state heat flow method, in accordance with ASTM C518, using a new thermal conductivity meter, the Fox 200 of LaserComp Corporation. Average thickness of the samples was measured in accordance with the standard ASTM D 5736-95, and air permeability was determined by ASTM D 737-96 method. The test results show that thermal insulation properties of the composites vary significantly, depending on the type of cellulosic fiber, the pretreatment of fibers, ratio of cellulosic to synthetic fibers, and overall densities of the composite.