Low dielectric loss and infrared emissivity coating with enhanced mechanical property by grafting modification of EPDM

Composite coating materials or structures with low infrared emissivity and high radar transmittance are in ur-gent need in practical applications, among which binder is one of the important factors affecting the mechanical properties, infrared and dielectric properties of coatings. Acrylic acid (AA) and maleic anhydride (MAH) were used as graft monomers to modify ethylene propylene diene monomer (EPDM) binder. Composite coating with low infrared emissivity and low dielectric properties was prepared by using modified EPDM as binder, floating aluminum (Al) powder and antistatic carbonaceous fiber (CF) as filler. The effects of the type and amount of modified monomer on the mechanical properties, infrared emissivity and dielectric properties of the binder and the composite coating were systematically studied. The results show that the tensile strength (sigma b) and elongation at break (e) of the composite coating can be increased by 32% and 18%, respectively, by appropriate grafting modification of the binder. The infrared emissivity and the dielectric properties of the composite coating has a slight change with the increase of graft monomer content. Grafting modification of the binder improves the compatibility, wettability and interfacial bonding between filler and binder, which remarkably enhanced the mechanical and comprehensive properties of the composite coating. The effect mechanism of grafting modifi-cation of AA and MAH is disclosed from the aspects of polarity, branching and crosslinking. This work increases the selection range of binders needed to prepare low infrared emissivity materials.