Polyester core materials and structural sandwich composites thereof

Abstract

High-strength, chemically and thermally stable, closed-cell foams, useful as structural core materials in sandwich composites. The core materials of the invention display anisotropic properties. The core materials of the invention are amenable to vacuum-mediated resin bonding to composite skins to provide lightweight, high-strength structural sandwiches suitable for use in a variety of applications, such as marine applications, construction, aviation, rapid transit, and recreational vehicles.

What is claimed is:  
     
         1 . A composite comprising a foamed polyester core material bonded to one or more structural skins, wherein the core material is anisotropic.  
     
     
         2 . The composite of  claim 1 , wherein the core material is bonded between two structural skins.  
     
     
         3 . The composite of  claim 1 , wherein the one or more structural skins comprises a thermoplastic polymer, a thermosetting polymer, wood, an inorganic material, or a metallic material.  
     
     
         4 . The composite of  claim 3 , wherein the thermoplastic or thermosetting polymer comprises glass fibers, metallic fibers, inorganic fibers, or carbon fibers.  
     
     
         5 . The composite of  claim 1 , wherein the one or more structural skins comprise a structural sandwich composite.  
     
     
         6 . The composite of  claim 1 , further comprising a resin bonding at least one of the skins to the core material.  
     
     
         7 . The composite of  claim 1 , wherein the foamed polyester core material comprises foamable polyethylene terephthalate, foamable polybutylene terephthalate, foamable polyethylene naphthalate, a foamable copolymer of polyethylene terephthalate, a foamable copolymer of polybutylene terephthalate, a foamable copolymer of polyethylene naphthalate, or a mixture thereof.  
     
     
         8 . The composite of  claim 1 , wherein the foamed polyester core material comprises foamable polyethylene terephthalate.  
     
     
         9 . The composite of  claim 1 , wherein the core material comprises a nucleating agent, a fire retardant, or a reinforcing agent.