Thermomechanical response of high performance benzoxazine/epoxy polymers based nanocomposites

Abstract

This study investigates the thermomechanical performance of advanced nanocomposites reinforced with Multi-Walled Carbon Nanotubes (MWCNTs) and Aluminum Nitride nanoparticles (AlN), using two distinct thermosetting resins: polybenzoxazine (PBz) and epoxy. PBz was selected for its exceptional thermal stability, radiation shielding, low moisture absorption, and mechanical resilience, while epoxy offers benchmark processing efficiency, structural reliability, cost-effectiveness, and superior mechanical properties. Nanocomposites containing 1 wt.% AlN or MWCNTs were prepared and characterized. Thermal properties were evaluated through Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA), while thermomechanical behavior was assessed using Dynamic Mechanical Analysis (DMA). The mechanical performance was characterized through quasi-static tensile and creep tests, as well as dynamic compression tests using the Split Hopkinson Pressure Bar (SHPB). The results demonstrated significant improvements in both thermal stability and mechanical strength. Notably, under high strain rates, PBz reinforced with 1 wt.% MWCNTs exhibited a 125.52% increase in failure stress compared to the neat PBz resin, while epoxy reinforced with 1 wt.% MWCNTs showed a 58.6% improvement. In contrast, AlN nanoparticles provided moderate improvements, with PBz-1%AlN and epoxy-1%AlN achieving 57.28% and 24.4% increases in failure stress, respectively. The study also highlights the inherent advantages of PBz over epoxy, as PBz-based nanocomposites consistently outperformed their epoxy counterparts in terms of mechanical strength, creep resistance and dynamic response. This comparative analysis highlights the synergistic effects of nanofillers in optimizing both thermal and mechanical properties of PBz and epoxy nanocomposites. These findings provide crucial insights for their potential applications in high-performance applications within the aerospace, automotive, and defense industries, where lightweight materials with superior strength, durability, and thermal stability are critical.