Cellulose nanocrystal reinforced oxidized natural rubber nanocomposites

• Oxidation of NR latex with different degrees was successfully performed.
• CNC reinforced NR nanocomposites were prepared.
• Unconventional compatibilization was obtained by matrix modification.
• The effect of the degree of oxidation of the NR latex was investigated.
• Improved properties were observed when using a low degree of oxidation.

Natural rubber (NR) latex particles were oxidized using KMnO4 as oxidant to promote the insertion of hydroxyl groups in the surface polyisoprene chains. Different degrees of oxidation were investigated. Both unoxidized and oxidized NR (ONR) latex were used to prepare nanocomposite films reinforced with cellulose nanocrystals (CNCs) by casting/evaporation. The oxidation of NR was carried out to promote chemical interactions between the hydroxyl groups of ONR with those of CNCs through hydrogen bonding. The effect of the degree of oxidation of the NR latex on the rheological behavior of CNC/NR and CNC/ONR suspensions, as well as on the mechanical, swelling and thermal properties of ensuing nanocomposites was investigated. Improved properties were observed for intermediate degrees of oxidation but they were found to degrade for higher oxidation levels.