Mechanical and viscoelastic properties of natural rubber/ reclaimed rubber blends

Addition of reclaimed rubber affected mechanical properties, processing and rheological behavior of rubber compounds. Sulfur left in reclaimed rubber affected curing process of NR/reclaimed rubber blends. The most suitable curing was achieved with ratio 1:1 of natural rubber and reclaimed rubber which was used in this study. Presence of fillers in reclaimed rubber, non-homogeneity of phases, non-uniform filler dispersion and lower molecular weight of reclaimed rubber due to chain scission in reclaiming process caused diminishing of mechanical properties of NR/reclaimed blends, particularly dynamic-based properties. Reclaimed rubber also affected rheological behavior of natural rubber. In a strain sweep viscoelastic test, it could be observed that NR/reclaimed blend show more non-linear viscoelastic and viscous behavior than predicted one which was due to non-homogenized phases. This non-homogenized morphology was detected using scanning electron microscopy (SEM) and the blend with ratio 1:1 had the most homogenized morphology.