Controllable synthesis of the Al4B2O9 nanowhisker and their applications in reinforced polyhydroxyalkanoate composites

Large quantities of aluminum borate (Al4B2O9) nanowhiskers have been successfully synthesized by sol–gel and post-thermal-treatment methods. A series of experiments have been conducted to obtain an optimum condition for generating nanoscale precursor for the synthesis of Al4B2O9 nanowhiskers with an average diameter of 20–40 nm and length of several hundred nanometers, respectively. With decreasing boron content, the crystallized temperature is reduced, and the structure of Al4B2O9 phase is different in the Al2B3 and Al2B system. In addition, the effects of Al4B2O9 nanowhiskers on the mechanical properties of biodegradable polyhydroxyalkanoate (PHA) have been studied. It is worth noting that with adding the 0.6 wt% Al4B2O9 nanowhiskers, the mechanical properties of PHA composites are improved, the elongation to break increased by 13.5%, the ultimate tensile increased by 106.8% and yield strength increased by 190% compared with the pure PHA.