Neat Resin, Adhesive and Composite Properties of Reactive Additive/PETI-5 Blends

Abstract

PETI-5 (5000 g mol −1) is a relatively new adhesive and composite matrix that exhibits good processability and excellent properties. However in the fabrication of complex composite parts (i.e. skin stringer and support frames), better processability would offer distinct advantages. In an effort to improve the processability of PETI-5, a novel reactive additive was prepared and used to formulate blends. The reactive additive is a mixture of relatively simple phenylethynyl containing imides. As such, it exhibited solubility in a variety of solvents such as N-methyl-2-pyrrolidinone, a relatively low softening temperature ∼185°C) and a low melt viscosity (∼0.1–0.3 Pa s at 250°C). Neat resin blends prepared by physically mixing imide powders of the reactive additive and PETI-5 were thermally and rheologically characterized. Blends were also prepared by mixing NMP solutions of PETI-5 amide acid and the reactive additive (imide form). These solutions were subsequently used to prepare adhesive film and unidirectional carbon fibre tape using unsized IM7 fibre. The reactive additive/PETI-5 blends were used to fabricate titanium adhesive panels and composites under 0.54 MPa or less for 1 h at 350–371°C. The effect of reactive additive content on the physical, rheological, adhesive and carbon fibre laminate properties was determined. One formulation exhibited a decrease in melt viscosity (i.e. improved processability) without effecting open hole compression, compression properties after impact or microcrack behaviour. The neat resin, adhesive and composite properties of these reactive additive/PETI-5 blends and their cured polymers will be discussed.