Influences of Thickness and Fabric for Sound Absorption of Biopolymer Composite

Abstract

Biopolymer foam was prepared by the reaction of bio-monomer based on vegetable oil with commercial Polymethane Polyphenyl Isocyanate (Modified Polymeric-MDI). The acoustic study of biopolymer foam was examined by impedance tube test according to the ASTM E-1050 and laminated with three types of textile such as polyester, cotton and single knitted jersey. It was revealed that the thicker the fabric the higher the sound absorption coefficient (α) at medium frequency level. The higher the number of layers or thickness of the fabric, the sound absorption through the fabric increases at medium frequency but after the maximum it remains almost unaltered. Three layer of cotton fabric gives maximum α approximately equal to 1 which is 1.104 mm thickness at frequency level of 3000-3500Hz and single knitted jersey gives maximum α at 4th layer of 2200-2700Hz. Meanwhile , the α of biopolymer foam laminated with polyester fabric approximately equal to 1 at lower frequency level of 2000-3000Hz with lower thickness that is 0.668mm. Polyester fabric with lowest thickness shows better α at lower frequency level due to the structure of the fabric. The relationships among the fiber properties such as fiber density, fiber diameter, and fibrous material layer were considered as a factor that influences the sound absorption property.