(217ef) Effect of Nanocrystalline Cellulose On the Microstructure and Properties of Bio-Based P(3,4)HB/Pbs Composites

Poly(3-hydroxybutyrate-co-4-hydroxybutyrate)(P(3,4)HB), as a kind of eco-friendly biodegradable polymeric materials, has many excellent properties such as biodegradability and biocompatibility as well as outstanding mechanical properties in comparison with conventional petroleum-based plastic. P(3,4)HB also possesses some disadvantages including slow crystallization rate and poor mechanical properties, which greatly limit its application. Although the blending modification of P(3,4)HB with another ductile biodegradable polymer such as poly(butylene succinate) (PBS) is a practical and economic strategy, most blending components are usually incompatible with it, which leads to poor interfacial adhesion and phase separate and subsequently weakens the mechanical properties of the composites. Thus, the immiscible blends should be compatibilized with an effective and practicable method without weakening their strength and stiffness.

In this paper, on the basis of synthesis of nanocrystalline cellulose (NCC) and surface modified NCC (mNCC), (P(3,4)HB)/PBS/mNCC ternary composites were prepared by solvent casting method. The effects of mNCC on the microstructure, crystallization behavior and dynamic mechanical properties of the composites were systematically investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), differential scanning calorimetric (DSC) and dynamic mechanical analysis (DMA). TEM and SEM results show that mNCC can distribute individually in nanoscale in the matrix and the phase-separated phenomenon of P(3,4)HB/PBS is weakened obviously, which reveals that the nanofiller can act as compatibilizer by retarding the coalescence of the dispersed phase-separated particles. DSC results indicate that small amount of mNCC dispersed in P(3,4)HB/PBS matrix can act as a nucleating agent and facilitate the crystallization of polymer. The storage modulus of the composites is enhanced greatly with the increase of mNCC, attributing to the fact that the stiff rod-like mNCC can homogeneously disperse in P(3,4)HB/PBS matrix and act as a reinforcing agent by restricting the motion of the polymer chains.