Evaluation of mechanical, thermal and tribological properties of benzoxazine-modified polyoxymethylene composites

Polyoxymethylene (POM) is increasingly used to replace metals in moving components because of its corrosion resistance and high specific strength; however, its insufficient heat resistance and wear resistance limit its application under demanding service conditions. In this study, bisphenol-A/aniline-based benzoxazine (BZ) was used as a low-loading modifier, and BZ/POM composites were prepared by melt blending (210 °C) and compression molding (220 °C) while exploiting the thermal ring-opening polymerization of BZ within the POM processing range. The effects of BZ content (0–0.5 wt%) on the mechanical, thermal, and tribological properties were investigated. All properties showed non-monotonic behavior: the optimum mechanical performance was obtained at 0.3–0.4 wt% BZ (tensile strength +15.2% and flexural strength +62.7%), the decomposition temperature increased monotonically (temperature at the maximum decomposition rate +19 °C), and the coefficient of friction decreased in a threshold-like manner to a minimum of 0.1192 at 0.4 wt% BZ (a reduction of 29.3%). A BZ content of 0.4 wt% provided the best overall balance among the mechanical, thermal, and tribological properties, offering a new route for modifying thermoplastic engineering plastics through the in-situ polymerization of thermosetting monomers.