Mechanical and microwave absorbing properties of in situ prepared hydrogenated acrylonitrile-butadiene rubber/rare earth acrylate composites

Lanthanum oxide (La2O3), samarium oxide (Sm2O3) and acrylic acid (AA) were in situ reacted in hydrogenated acrylonitrile-butadiene rubber (HNBR) to obtain HNBR/acrylate and HNBR/acrylate/multi-walled carbon nanotubes (MWNTs) composites. Fourier transform infrared spectrum analysis showed the absorption peaks of carbon-carbon double bonds of the acrylates became weak after curing at elevated temperatures, indicating the self-polymerization of acrylates and their participation in crosslinking reactions of HNBR. The morphology of composites was characterized by scanning electron microscopy and X-ray diffraction analysis, and the well dispersion of acrylates was attributed to the in situ reactions during curing. The tensile strength of HNBR/La2O3/AA/MWNTs and HNBR/Sm2O3/AA/MWNTs composites reached 25.2 and 17.6 MPa, and their stress at 100% extension reached 8.4 and 7.4 MPa, indicating the good reinforcement of in situ formed acrylates and MWNTs on HNBR. The glass transition temperature of HNBR increased to a limited extent because of the addition of AA and La2O3. The HNBR/La2O3/AA/MWNTs and HNBR/Sm2O3/AA/MWNTs composites had good microwave absorbing properties, with the maximum reflection loss of −9.0 and −13.5 dB, respectively, and broad absorption bands.