Bionanocomposites containing SnO2 with improved chemical resistance and hydrophobic behaviours for applications in food packaging industry
(1. Department of Chemistry, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, Chennai-602 105, Tamil Nadu, India;
2. Department of Chemistry, Vel Tech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology, Chennai-600 062, Tamil Nadu, India)
2. Department of Chemistry, Vel Tech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology, Chennai-600 062, Tamil Nadu, India)
Abstract: The influence of poly(asparagine-co-phenylalanine) (P(Asn-co-Phe)/SnO2) on the protection performance of epoxy coating was investigated. The electrochemical impedance spectroscopy (EIS) analysis indicates the better protection against coating degradation of epoxy (EP)-P(Asn-co-Phe)/SnO2 nanocomposite on tinplate compared to that of pure epoxy coatings. The coating resistance (Rcoat) of the EP-P(Asn-co-Phe)/SnO2 nanocomposite is found to be 3854.70 k？·cm2. The Rcoat of EP-P(Asn-co-Phe)/SnO2 nanocomposite coating is found to be over 38 times greater than that of the EP coating. Scanning electrochemical microscopy (SECM) analysis shows less current distribution for the EP-P(Asn-co-Phe)/SnO2. The analyses of degradation products by XRD and SEM/EDX confirm the influence of functionalized SnO2 particles on the protecting ability of epoxy coating. The hydrophobic nature of the EP-P(Asn- co-Phe)/SnO2 nanocomposite coating (θ=133°) is confirmed by water contact angle measurement. The resultant nanocomposite coatings display enhanced mechanical properties. The results show that the EP-P(Asn-co-Phe)/SnO2 nanocomposite in wells increased the antibacterial activity as compared with pure EP. Therefore, it is concluded that the newly synthesized EP-P(Asn-co-Phe)/SnO2 nanocomposite provides an outstanding barrier and mechanical properties due to the addition of P(Asn-co-Phe)/SnO2 nanoparticles to the epoxy matrix, which obstructs the degradation of materials and assists in prolonging the life of the coated steel.
Key words: tinplate; epoxy; SnO2; nanocomposite coatings; copolymer; thermal stability; hardness