Preparation and properties of peroxide prevulcanized natural rubber/Ag nanocomposites: effect of AgNO3 adding sequence on mechanical and antimicrobial properties

摘要

The effect of silver nanoparticles (AgNPs) prepared by different AgNO3 adding sequence on antimicrobial and tensile properties of peroxide prevulcanized natural rubber (PPNR) has been investigated. AgNO3 is added into NR latex either before or after prevulcanization. It is used as a source of AgNPs, which are generated in situ in PPNR. Spherical AgNPs are formed in PPNR as observed by UV-Vis spectra and transmission electron microscopy images. Crosslink density of PPNR/Ag nanocomposites prepared by adding AgNO3 before prevulcanization tends to decrease as AgNO3 content increases due to competitive reduction between silver ions and ferric ions. Significant decrease of tensile strength is observed at AgNO3 concentration of 5000 ppm whereas M-100 and M-300 are slightly affected. At each AgNO3 concentration, PPNR/Ag nanocomposites prepared by adding AgNO3 after prevulcanization has higher tensile strength, M-100 and M-300 than those of the nanocomposites prepared by adding AgNO3 before prevulcanization. This is because adding AgNO3 after prevulcanization does not decrease the crosslink density of the rubber molecules. PPNR/Ag nanocomposites prepared by adding AgNO3 after prevulcanization show higher Ag+ release amount and hence higher% bacterial reduction for both E. coli and S. aureus than those of the nanocomposites prepared by adding AgNO3 before prevulcanization.