CHEMISTRY AND ADHESIVE PROPERTIES OF PHENYLETHYNYL-TERMINATED PHENYLQUINOXALINE OLIGOMERS

As part of a program to develop high performance/high temperature stru ctural resins for potential aeronautical applications, phenylethynyl-t erminated phenylquinoxaline oligomers were prepared, characterized, th ermally cured and the cured resins were evaluated as adhesives. The ph enylquinoxaline oligomers were prepared by conventional and aromatic n ucleophilic displacement routes and chain terminated with mono or di(p henylethynyl) groups. The oligomers were melt pressed into thin films, compression molded into tensile and compact tension specimens, and fa bricated into titanium-to-titanium single lap shear adhesive specimens . The oligomers were generally compression molded for 1 hr at 350 degr ees C under pressures ranging from 0.10 to 1.4 MPa. The phenylquinoxal ine oligomer prepared via aromatic nucleophilic displacement exhibited better processability and higher tensile shear strengths than those o f the oligomers prepared via the conventional synthetic route. The syn thesis, physical and mechanical properties of these oligomers and thei r cured polymers are presented.