Polypyrrole doped epoxy resin nanocomposites with enhanced mechanical properties and reduced flammability

Abstract

For the liquid epoxy nanosuspensions with both fibril and spherical polypyrrole (PPy) nanostructures, a stronger PPy nanofibers/epoxy interaction and more temperature stable behavior with a lower flow activation energy of nanosuspensions with nanofibers (54.34 kJ mol À1 ) than that with nanospheres (71.15 kJ mol À1 ) were revealed by rheological studies. As well as the common enhancing mechanism of limiting crack propagation in the polymer matrix, the nanofibers further initiated the shear bands in the epoxy resin to give a higher tensile strength (90.36 MPa) than that of pure epoxy (70.03 MPa) and even that of the epoxy nanocomposites with nanospheres (84.53 MPa). With a larger specific surface area, the nanofibers rather than nanospheres were observed to reduce the flammability of epoxy more efficiently by assisting more char formation of the epoxy resin. The hydroxyl groups formed between the protons of the doped acid in the PPy nanofillers and the epoxy broke the conjugate structure of PPy, leading to a higher bandgap in the nanocomposites (E g1 ¼ 3.08 eV for 1.0 wt% PPy nanofibers) than that of pure nanofillers (1.8 eV for PPy nanofibers and 1.2 eV for PPy nanospheres). Due to the high aspect ratio, the PPy nanofibers could form the conductive path more easily than the PPy nanospheres to provide a lower percolation threshold value. The real permittivity was observed to increase with increasing the PPy nanofiller loading, and the enhanced permittivity was interpreted by the interfacial polarization.

Modified nano Fe2O3-epoxy composite with enhanced mechanical properties

“…The fracture surfaces of the A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 16 neat epoxy resin show river lines, which are the characteristics of brittle fracture behavior (Figure 13a). While the surface of ENC containing A-P-Fe 2 O 3 NPs is somewhat rough.…”

Mechanical performance of epoxy matrix hybrid nanocomposites containing carbon nanotubes and nanodiamonds

“…carbon nanofibers, graphene and graphite platelets and many other nanoreinforcements are used in thermo and thermosetting polymers for a variety of mechanical and functional properties including increased strength, enhanced toughness, electrical conductivity, shape memory effect, flame resistivity, rheological behavior and electromagnetic filed absorption [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32].…”

Fabrication of Fe3 O4 @SiO2 nanocomposites to enhance anticorrosion performance of epoxy coatings

“…Until now, many researchers tend to improve the performance of epoxy resin such as the anticorrosion and mechanical properties through adding a certain content of nanocomposites or other materials. [7,8] The development of nanoparticles and their application in the fields of paints and coatings have been studied. [9] And the inorganic nanoparticles dispersed in a polymeric vehicle to fill the surface cavities, leading to the reduction in surface defects like micropores and microcracks and enhancing the integrity of coatings through adhesion between coating and metal surface.…”