The outstanding interfacial adhesion between acrylo-POSS/natural rubber composites and polyamide-based cords: ‘An environmentally friendly alternative to resorcinol-formaldehyde latex coating’

Abstract Resorcinol formaldehyde latex (RFL) dipping system, very effective to enhance adhesion between rubber and cords in the tire industry, has substantial health & environmental (i.e., toxicity) and commercial (i.e., being time-consuming and expensive) negative effects. The present work eliminates these disadvantages, and more importantly reports much better adhesions between natural rubber (NR) and textile cords than RFL itself by proposing Acrylo-polyhedral oligomeric silsesquioxane (A-POSS), a new generation reactive hybrid nanoparticle. The H-adhesion forces between A-POSS/NR and virgin Nylon 6.6 cord highly increased to 123.0 N whereas the same forces between NR and RFL coated Nylon 6.6 was only 95.8 N. A thin layer of NR/A-POSS on the surface of Nylon 6.6 cords in SEM images confirmed a good interfacial H-adhesion between the Nylon 6.6 cord and NR/A-POSS even at the low A-POSS loadings. In addition, higher work of adhesion between NR/A-POSS and virgin Aramid than that of between NR and virgin Aramid was obtained. The strong adhesion between NR and polyamide cords in the presence of A-POSS was revealed by FTIR and NMR analyses. A-POSS/NR provided enhanced thermal stability, crosslinking density, and mechanical properties. Moreover, the tan δ value was reduced by ~9% for NR/A-POSS composites compared to the NR skim composite indicating better dynamic performance for a moving tire. Overall, it was concluded that the use of A-POSS nanoparticles in NR composites can be alternative to RFL dipping method currently being used in the tire industry due to enhanced adhesion between rubber composites and the polyamide cords.