Sound absorption and compressive property of PU foam‐filled composite sandwiches: Effects of needle‐punched fabric structure, porous structure, and fabric‐foam interface

The flexible polyurethane (PU) foam‐filled composite sandwiches are constructed using three types of needle‐punched fabrics (upper layer), PU foam (core layer), and nylon (bottom layer). Different contents of deionized water were used to adjust the pore size and bulk density of PU foam by free‐foaming. Effects of needle‐punched fabric components, cell structure, and fabric‐foam interface on sound absorption and compressive property of the composite sandwiches were investigated. Fabric‐foam interface contributes to improve high‐frequency sound absorption efficiency. When containing 0.5 wt% water in the core and nylon‐glass grid needle‐punched composite fabric (NPUN‐G) in the upper face, the composite sandwiches exhibited optimal sound absorption of 0.78 at low frequency of 450 Hz, and optimal compressive strength of 14.4 kPa. Combination of needle‐punched composite fabric improved the sound absorption coefficient and compressive strength, as high as 223% and 121%, respectively, compared with pure PU foam. This study provided an important basis for the preparation of high‐strength composite sandwiches with low‐frequency sound absorption.