Effect of Polysulfone and Graphene Nanosheets on the Flexibility of Epoxy Coatings

Epoxy resin has remarkable properties including excellent mechanical and electrical properties, thermal and chemical stability, and resistance to creep. On the other side, these resins are brittle with low resistance toward crack initiation and its growth. In order to solve this problem, thermoplastic polysulfone and graphene nanosheets have been used as filler for improving the flexibility of epoxy coatings. The effect of adding different amounts (1, 0.5, 2.5, 5 wt%) of polysulfone and 0.5 wt% of graphene nanosheets on the epoxy properties was investigated by thermal analysis (DSC), tensile strength, impact resistance and determining the gel content of samples. The results showed that the tensile strength of epoxy resin increased by adding polysulfone, and the graphene nanosheets could improve flexibility of the sample containing 1 wt% polysulfone. The study of thermal properties of cured samples by means of DSC analysis showed that the addition of polysulfone into the epoxy network resulted in changing the glass transition (Tg) of the resin. With incorporation of graphene nanosheets into the polymer matrix, the modulus decreased due to the reduction in number of crosslinks. The study in impact resistance of the samples showed that those containing 1 wt% polysulfone and 0.5 wt% graphene displayed high strength and impact resistance. These types of compounds can be used in flexible and anticorrosion coatings.