Effect of salt water exposure on foam-cored polyurethane sandwich composites

Abstract

This study investigated the effect of moisture absorption on the mechanical performance of polyurethane sandwich composites. The core material was a closed cell polyurethane foam. Face sheets were made of E-glass/polyurethane composite laminates. Vacuum-assisted resin transfer molding process was used to manufacture specimens for testing. The foam core, laminates, and sandwich composites were submerged in salt water for prolonged periods of time. Mechanical property degradation due to moisture absorption for each constituent was evaluated. Compression test was performed on the foam core samples. Laminates were evaluated by three-point bending tests. The interfacial bond strength in the sandwich structure was evaluated by double cantilever beam mode-I interfacial fracture test. The testing results revealed that the effect of salt water exposure on the compressive properties of the foam core is insignificant. The flexural modulus of polyurethane laminates degraded 8.9% and flexural strength degraded 13.0% after 166 days in 50% salinity salt water at 34°C conditioning. The interfacial fracture toughness of polyurethane sandwich composites degraded 22.4% after 166 days in 50% salinity salt water at 34°C conditioning.

Integrated preparation and properties of polyurethane‐based sandwich structure composites with foamed core layer

“…The pure PU foam was prepared by Caglayan et al, [ 12 ] and its compressive strength was 0.88 MPa. Huo et al [ 3 ] prepared a closed cell PU foam, and its compressive strength was 994.5 kPa. By comparison, the compression strength of a foaming agent of 2% was 4.16 MPa and increased by 372.7%, 318.3%, respectively.…”

“…This is of great significance for the preparation of PU foam as core materials and fiber reinforced PU composites as surface layer with excellent properties. [3][4][5] The sandwich-structure panel is usually composed of top and bottom panels with high strength and stiffness and a light mass-large volume core layer, thus has excellent lightweight, high strength, and some other special functions. For the PU sandwich-structure panel, the upper and lower surface panel materials are usually metal or fiber reinforced composite panel, [6,7] and the core layer is PU-based material.…”

“…This is of great significance for the preparation of PU foam as core materials and fiber reinforced PU composites as surface layer with excellent properties. [ 3–5 ]…”

“…This is due to the larger amount of the deionized water generates more foam pores thus to reduce the compression performance of PU foam. Huo et al [ 3 ] studied the mechanical properties of PU SSCs resulted from hygroscopicity, and indicated little effect of salt solution on the compressive properties of foam material. However, the toughness of PU SSCs decreased by 22.4% after soaked in a 50% concentration salt water at 34°C for 166 days.…”

Effect of Seawater Exposure on Impact Damping Behavior of Viscoelastic Material of Pounding Tuned Mass Damper (PTMD)

“…It is well known the chloride diffusion will cause damages to various materials [72,73]. Huo et al [74] investigated the mechanical property of closed cell polyurethane foam immersed in salt water and the experimental results indicated that the flexural modulus and strength decreased by 8.9% and 13%, respectively, after 150 days of exposure to salt water. Saharudin et al [75] tested halloysite nanotubes-polyester nanocomposites and found that the storage modulus, tensile properties and flexural properties of polyester and its nanocomposites decreased after seawater exposure.…”