Confinement effects at nanoscale in natural rubber composites: Influence on macroscopic properties

The study of molecular level interactions in elastomer composites has got very scant attention even though a large number of studies are going on in this topic. This work embodies the understanding of confinement effects in natural rubber (NR)/ ZnO composites from micro to nano length scales, and their influence on macroscopic properties of the composites. The interactions between fillers and matrix are characterized from the Donth's approach, which allows estimating the cooperativity size N_α at the glass transition, N_α being directly related to the filler-matrix interactions. The improved properties of NR-nano ZnO composites can be attributed to microstructural and morphological changes due to nano ZnO in the NR matrix. A correlation between N_α, the constrained volume C_v and the thickness of immobilized polymer chains χ_m at the glass transition has also been established. Thus, this work proves that the Donth's approach is a powerful probe to estimate the enhance of mechanical properties in nanocomposites from calorimetric investigations.