New imide-based thermosets with propargyl ether groups for high temperature composite application

Development of new thermosetting polyimides with good processability is highly demanded. Oligomers with two imide cycles (bisimides), containing propargyl ether groups using 4-aminophenyl propargyl ether were prepared for the first time. Bisimides were synthesized without using of toxic solvents in benzoic or acetic acids. Use of acids as solvent allows to combine synthesis of bisimides with reaction of removing tret-butyloxycarbonyl group from amine in one step. Chemical structure of bisimides was confirmed using H-1, C-13 NMR, FT-IR and elemental analysis. Pre-polymers exhibited wide temperature processing window and good solubility in low boiling point organic solvents. Thermal curing was investigated using differential scanning calorimetry (DSC) and FT-IR analysis. Propargyl ether groups cross-link completely after 1 h at 300 C. Thermogravimetric analysis (TGA) indicated that the temperatures of 10% weight loss of cured polymers in nitrogen and air atmosphere were in the ranges of 492-499 C and 503-515 C, respectively. Samples of Carbon fiber reinforced plastics (CFRP) were prepared using bisimides with propargyl ether groups and investigated by dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). CFRP demonstrated glass transition temperature in the range of 309-370 C and homogeneous structure of cross-section sample. Therefore, new highly thermally stable ther-mosets with great processability, prepared by eco-friendly synthesis for using as high performance polymer matrix for CFRP were developed in our work.