Metal adhesive properties of polyamides having the 2,3-bis(1,4-phenylene)quinoxalinediyl structure

Polyamides were synthesized by interfacial polycondensation of 2,3-bis(4-ch loroformylphenyl)quinoxaline (BCFPQ) and several aliphatic diamines using a phase transfer catalyst, and their adhesive property for stainless steel w as investigated. The inherent viscosity of the obtained polyamides ranged f rom 0.37 to 1.24 dL g(-1). The glass transition temperatures of the polyami des ranged between 154 and 201 degrees C, and their thermal decomposition t emperatures were above 450 degrees C. The polyamides were soluble in severa l organic solvents, including m-cresol, N-methyl-2-pyrrolidone (NMP), and f ormic acid. The adhesive property for stainless steel was examined by a sta ndard tensile test. One member of the series; polyamide PS, derived from BC FPQ and 1,8-octanediamine, displayed high tensile strength with values of 2 32 kgf cm(-2) at 20 degrees C, 173 kgf cm(-2) at 120 degrees C, and 137 kgf cm(-2) at 180 degrees C. Thus, the tensile strength of P8 decreased at 180 degrees C, but the decrease was much smaller than that of an epoxy resin i n wide use as a metal adhesive. Heat distortion temperature, measured by th ermal mechanical analysis, of PS was 191 degrees C. This suggested that PS possessed high thermal resistance in metal adhesives. (C) 1999 John Wiley & Sons, Inc.