Microwave Synthesis of Phenylethynyl Imide Oligomers: Neat Resin and Composite Properties of PETI-2982-4

Abstract

PETI-298 is a high temperature/high performance matrix resin that is processable into composites by resin transfer molding (RTM), resin infusion, and vacuum-assisted RTM techniques. It is prepared by the conventional amide acid approach in a polar aprotic solvent from the reaction of an aromatic anhydride and a combination of diamines and endcapped with phenylethynylphthalic anhydride. As a means to eliminate solvent and decrease reaction time in order to address final resin cost, the microwave synthesis of PETI-298 was investigated. The monomers were manually mixed and placed in a microwave oven for various times to determine optimum conditions. The resultant materials were characterized for thermal and rheological properties and compared with PETI-298 prepared by the classic amide acid approach. The synthetic process was subsequently scaled-up to 330 g. Three batches were prepared and combined to give ° 1 kg of material that was subsequently used to fabricate flat laminates on T650 carbon fabric by RTM. The composite panels were analyzed and mechanical properties determined. These properties were compared with those fabricated from PETI-298 prepared by the classic amide acid approach. Based on solubility characteristics, melt viscosity and Fourier transform infrared spectroscopy, the phenylethynyl group did not react under the conditions investigated. This approach is applicable to the synthesis of a variety of phenylethynyl-terminated imide oligomers