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

Abstract Lanthanum oxide (La 2 O 3 ), samarium oxide (Sm 2 O 3 ) 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/La 2 O 3 /AA/MWNTs and HNBR/Sm 2 O 3 /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 La 2 O 3 . The HNBR/La 2 O 3 /AA/MWNTs and HNBR/Sm 2 O 3 /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.