Effects of Hydroxyl‐Terminated Hyperbranched Polyamide on the Compatibility and Properties of Dimer Acid‐Based Polyamide/Wood Flour Composites

ABSTRACT The hydroxyl‐terminated hyperbranched polyamide (HHBP) was synthesized to improve the compatibility between dimer acid‐based polyamide (DAPA) matrix and wood flour (WF) fillers, thereby enhancing the overall performance of the composites. A series of DAPA/WF composites with varying HHBP and WF contents were prepared via melt blending. Fourier transform infrared spectroscopy (FT‐IR), scanning electron microscopy (SEM), dispersion homogeneity analysis, and gel fraction measurements were employed to characterize the chemical structure and micromorphology of the composites, and systematically investigate the effect of HHBP on their compatibility. HHBP serves as a bridge between WF and DAPA through intermolecular interactions such as hydrogen bonds, thereby improving their compatibility and enhancing interfacial bonding. Mechanical property analysis revealed that the introduction of HHBP significantly enhanced the tensile strength, right‐angle tear strength, and flexural strength of the composites. With increasing WF content, the mechanical properties of the composites were further improved. HHBP had a minor impact on the thermal stability of the composites. Furthermore, the incorporation of HHBP reduced the water absorption of the composites, thus prolonging their service life. At an HHBP content of 3%, the composites exhibited optimal compatibility and overall performance.