Synthesis and characterization of modified phenylethynyl imides

Abstract

As an ongoing effort to develop structural adhesives for high-performance aerospace applications, recent work has focused on phenylethynyl terminated imide (PETI) oligomers. The work reported herein involves the synthesis and characterization of a series of phenylethynyl containing oligomers designated LARC™ MPEI (modified phenylethynyl imide). These oligomers presumably contain mixtures of linear, branched and star-shaped molecules. The fully imidized polymers exhibited minimum melt viscosities as low as 600 poise at 335°C, significantly lower than equivalent molecular weight linear materials. Ti/Ti lap shear specimens processed at 288°C under 15 psi showed tensile shear strengths as high as ∼6000 psi and ∼5200 psi at ambient temperature and 177°C respectively. The chemistry and properties of these new MPEIs are presented and compared with an optimized linear PETI, LARC™ PETI-5.