the invention provides new compositions of matter that are capable of forming cross - linked polymeric materials upon reaction with various known epoxy - containing compositions . thus , the compositions of this invention are useful in the manufacturing of prepregs and laminates for pwb applications among many other uses . preferred compositions of this invention include substituted hydroxyarylphosphine oxide mixtures , the glycidyl ether derivatives , or the epoxy resin oligomer adducts derived therefrom . the materials provide for laminates that have higher glass transition temperatures , improved thermal stability , and that are free of halogen .