Mechanically robust and flame-retarded EPDM composites with high loading of Mg(OH)2 based on reversible crosslinking network from Diels-Alder reactions

•A thermoreversible crosslinking network based on Diels-Alder reaction was constructed in flame retardant EPDM composites containing high loading of MH.•The coordination between MH/carboxylic acid group could significantly improve the compatibility between MH and EPDM matrix.•The thermoreversible crosslinking could improve the flame retardancy and the degradation activation energy of EPDM-g-FA/MH composites.•The thermoreversibly crosslinked EPDM-g-FA/MH composites possess good mechanical properties as well as good reprocessability under high MH loading.