The effect of lanthanum trimethacrylate on the mechanical properties and flame retardancy of dynamically vulcanized PP/EPDM thermoplastic vulcanizates

A new kind of polypropylene/ethylene–propylene–diene monomer (PP/EPDM) thermoplastic elastomer (TPE) with good mechanical properties and flame retardancy was prepared via in situ peroxide-induced dynamic vulcanization using lanthanum trimethacrylate (LaTMA) as a reinforcing agent. The morphology, structure, and mechanical properties and reinforcement mechanism of PP/EPDM/LaTMA TPE were investigated by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, rubber process analyzer, cross-link density test, and so on. The flame retardancy was investigated by limiting oxygen index (LOI) test. The results showed that when the amount of lanthanum oxide was 4.96 phr and methyl methacrylate was 7.85 phr, the compatibility between EPDM and PP was greatly improved. Besides, the tensile strength, tear strength, elongation at break, and hardness (shore A) of PP/EPDM/LaTMA TPE were increased from 6.2 MPa, 41.7 kN m？1, 148%, and 81 up to 11.1 MPa, 77.3 kN m？1, 365%, and 89, respectively. And the LOI of PP/EPDM/LaTMA TPE was increased to 19.0%. The SEM images, the higher G′, and the ionic cross-link suggested that a strong filler–filler network was formed by the polymerization and the grafted of LaTMA in the PP and EPDM phase which enhanced the compatibility between PP and EPDM. The DSC and FTIR results further proved that during the processing