PROPERTIES OF IMIDE OLIGOMERS CONTAINING PENDENT PHENYLETHYNYL GROUPS

As part of a programme to develop high-performance/high-temperature st ructural resins for aeronautical applications, imide oligomers contain ing pendent phenylethynyl groups were prepared, characterized, thermal ly cured and the cured resins evaluated as films, mouldings, adhesives and composites matrices. lnitially a diamine containing a pendent phe nylethynyl group (3,5-diamino-4'-phenylethynylbenzophenone) was prepar ed and characterized. This compound was used to make amide acid and su bsequently imide oligomers containing pendent phenylethynyl groups. In order to control the distance between reactive sites, the concentrati on of pendent phenylethynyl groups was varied randomly along the oligo mer backbone. The amide acid oligomers in N-methyl-2-pyrrolidinone wer e processed into thin films, adhesive tape, carbon fibre prepreg and a lso converted into imide powder. After initial screening work was perf ormed on unoriented thin films, imidized powders and neat resin mouldi ngs to assess glass transition temperature, mechanical properties (ten sile properties and fracture toughness), melt dow behaviour and proces sability, one particular formulation was scaled up for more comprehens ive evaluation. This imide oligomer containing pendent phenylthynyl gr oups was fabricated into adhesive and composite specimens under 1.4 MP a for 1 h at 350-371 degrees C. Excellent mechanical properties were o btained at room temperature and 177 degrees C. The properties of this material are compared with those of a material of similar composition and molecular weight containing only terminal phenylethynyl groups.