New waterborne polyurethane-based nanocomposites reinforced with low loading levels of chitin whisker

New waterborne polyurethane (WPU)-based nanocomposites were prepared by incorporating low loading levels of chitin whiskers (ChWs) as the nanophase. The resultant WPU/ChW nanocomposites exhibited prominent enhancement in both strength and Young's modulus, and maintained an elongation of greater than ca. 500%. The ChW loading level of 3 wt% showed the maximum tensile strength (28.8 MPa) and enhanced Young's modulus (6.5 MPa), ca.1.8- and 2.2-fold over those of neat WPU. The active surface and rigidity of ChW facilitated formation of the interface for stress transferring and contributed to higher stress-endurance. As the ChW loading level increased, self-aggregation of ChWs resulted in a decrease in strength; however, the rigidity of ChW still supported the increase in Young's modulus, and the nanocomposites containing 5 wt% ChWs had the highest Young's modulus (9.6 MPa). This work enriches the research into achieving high mechanical performance of waterborne polyurethane-based nanocomposites by introducing a natural nanofiller, and this high performance 'green' bionanocomposites will likely have promising prospects.