Synthesis and properties of PMR type poly(benzimidazopyrrolone-imide)s

Processable PMR Poly(Pyrrolone-Imide)s Matrix Resins and their Short Carbon Fiber-Reinforced Composites

Processable poly(pyrrolone-imide)s (PPI) were prepared via PMR process from diethyl ester of 4,4′-(hexafluoroisopropylidene)diphthalic acid (6FDE), 3,3′, 4,4′-tetraaminodiphenyl ether (TADPE), p-phenylenediamine ( p-PDA) and monoethyl ester of cis-5-norbornene- endo-2,3-dicarboxylic acid (NE) using methyl alcohol as solvent. The homogenous PPI matrix resin solutions with 32 wt.% solid content had the low absolute viscosities in the range of 80-90 mPa s at 25 °C. The matrix resin solutions were stable for a period of > 2 months at the refrigerator temperature (4 °C) and showed good adhesion on carbon fibers. The matrix resin solutions could be thermally converted to B-stage end-capped prepolymer, which was then thermally processed to yield the fully-cured PPI. Experimental results demonstrated that the fully-cured PPI exhibited good thermal stability with glass transition temperatures of >400 °C and the thermal decomposition temperature of 525-537 °C. The onset temperatures of the DMA storage modulus curve for PPI-20 was as high as 395 °C and the storage modulus retention was 71% at 370 °C. The short carbon fiber-reinforced PPI composites (CF/PPI) were also fabricated. The CF/PPI composites showed excellent thermal stabilities and good mechanical properties, with glass transition temperature in the range of 413-421 °C and the storage modulus retention of 76-87% at 370 °C.

Synthesis and Properties of PMR Matrix Resins of Poly(Pyrrolone-Benzimidazole)s

PMR type of poly(pyrrolone-benzimidazole) copolymers (PPBI) were synthesized by the polycondensation of monoethyl ester of cis-5-norbornene-endo-2,3-dicarboxylic acid (NE), diphenyl-isophthalate (DPIP), diethyl ester of 4,4′-oxydiphthalic acid (ODPE) and 3,3′-diaminobenzidine (DAB) or 3,3′,4,4′-tetraamindiphenyl ether(TAD) in a mixing solution of anhydrous ethyl alcohol and N -methylpyrrolidone (NMP) under different temperature and pressure procedures. The resulting resin solution showed an excellent solubility in polar organic solvents and good stability at room temperature, while the corresponding PPBI molded powder and molded plate could be prepared by undergoing amidation, imidization, cyclization and crosslinking reactions when the reaction temperature would be increased from 150 to 350°C, especially, the crosslinking structure formed by the reverse Dials-Alder reaction at 270-290°C under 2.5-3.5 MPa pressure displayed by the pressure meter. The chemical reactions and properties of the resulting PPBI molded powders and molded plates were studied by means of FT-IR, TGA, DMA methods, and the results indicate that the PPBI materials obtained hold excellent thermal stability and processability, the initial decomposition temperature > 600°C and its T g defined by the peak temperature in tan δ curve from the DMA method is 448°C (DAB) or 423°C (TAD) for PPBI-20 molded plate.