Mechanical reinforcement of cellulose nanocrystals on biodegradable microcellular foams with melt-compounding process

The polymeric foamed composites were developed from the biodegradable poly(butylene succinate) (PBS) reinforced by the biomass-based cellulose nanocrystals (CNC) via the melt-compounding treatment. As the highly-crystalline and rigid nanoparticles, the presence of CNC in the polyester matrix can simultaneously enhance the flexural strength and flexural modulus of the foamed composites. With the addition of 5 wt% CNC, the flexural strength and modulus of the PBS foamed composite increased by 50 and 62.9 % in comparison with those of the neat foamed material. Furthermore, the introduction of the CNC significantly affected the cells morphology, structure and stability during the foaming process, which facilitated the increase of the cell density and the homogeneous cell size and distribution of the foamed composites. With the addition of 5 wt% azodicarbonamide as the chemical blowing agent and 5 wt% CNC as the bionanofillers, the foamed composite showed the increased cell density of 7.1 × 10⁵ cell/cm³, which was 69.1 % higher than that of the neat foamed material. The mechanical enhancement of the foamed composites was attributed to the nanoreinforcement of the CNC served as the stress transferring phase, and meanwhile the promising improvement on the cells structure and stability for the foamed composites was ascribed to the effect of the CNC acted as the nucleation component.