Investigations on Rheological and Mechanical Behavior of Poly(3-Hydroxybutyrate)/Cellulose Nanocrystal Based Nanobiocomposites

The work focused on the formation of percolation network by cellulose nanocrystals (CNCs) in poly(3-hydroxybutyrate) (PHB) matrix, which affects the rheological and mechanical properties of the polymer. Rheological investigations revealed the formation of a percolation network in the fabricated PHB/CNC films with a percolation threshold at a CNC loading of approximately 2 wt%. This observation was further confirmed by both mechanical analysis and modeling studies using Halpin-Kardos and Ouali models. The tensile modulus of the PHB/CNC films was found to be significantly higher (by approximate to 58%) than pristine PHB, leading to toughened and more flexible films. Fractured morphology showed the formation of bridge between the CNC and PHB matrix. The rheological parameters (linear and non-linear) were studied in detail to understand the viscoelastic properties of PHB/CNC nanocomposites. Rheological analysis was conducted over a wide range of temperature, and was coupled with differential scanning calorimetry measurements to examine the effect of temperature on the elastic modulus of the nanobiocomposites, especially near the crystallization temperature. The present study is expected to provide a better understanding of the effect of CNC dispersion on the structure-property relation of PHB/CNC nanocomposites. (C) 2015 Society of Plastics Engineers