Mechanical and sound adsorption properties of cellular poly (lactic acid) matrix composites reinforced with 3D ramie fabrics woven with co-wrapped yarns

• 3D ramie fabric/PLA cellular matrix composites were manufactured using co-wrapped yarns.
• The best mechanical performance was realized with the highest PLA content.
• All composites showed good sound absorption in the frequency range from 1000 to 2500 Hz.

In order to produce a light weight composite with reasonable mechanical and sound absorption properties, poly (lactic acid) (PLA) cellular matrix composites reinforced with three dimensional ramie fabrics woven with 3 types of co-wrapped yarns are manufactured by compression molding. The co-wrapped yarns are produced by wrapping PLA filament yarns around ramie core staple yarns on a fancy twisting machine, achieving more uniform resin and voids distribution and thus better resin impregnation for 3D thermoplastic composites. The linear density of PLA filament yarns for the co-wrapped yarns is varied to produce three kinds of light-weight composites with different fiber volume fractions and void contents. The surface morphology and yarn geometries of the molded composites are microscopically observed. The results of the mechanical testing show that the composite fabricated by the co-wrapped yarn with the highest PLA weight content has the best tensile and impact performance, mainly due to a better resin impregnation. The composites with co-wrapped yarn can absorb the sound energy in the frequency range from 1000 to 2500 Hz because of the existence of the voids evenly distributed in the composites.