A Novel Composite Film of Phenol‐Formaldehyde Resin and Thermoplastic Polyurethane With Improved Mechanical Properties

Abstract

To address the limitations in the mechanical properties of phenolic resin (PR), thermoplastic polyurethane elastomer (TPU) was evenly blended with PR. Blend films with different PR/TPU ratios were prepared via hot pressing. These films were characterized by Fourier transform infrared spectroscopy (FTIR), light transmittance tests, differential scanning calorimetry (DSC), dynamic thermomechanical analysis (DMA), scanning electron microscopy (SEM), and X‐ray diffraction (XRD), while their tensile properties were evaluated using an electronic universal testing machine. The results indicate partial compatibility and microphase separation between the two components in the blend films. Thermal and dynamic mechanical analyses revealed shifted glass transition temperatures and multiple relaxation peaks, confirming this partially miscible state. Furthermore, characteristic peaks associated with hydrogen bonding between the hydroxyl groups of PR and the urethane segments (NHCOO) of TPU were clearly identified in the FTIR spectra. At a PR/TPU mass ratio of 70:30, the composite film exhibited the highest tensile strength (4 MPa) and elongation at break (62%) among all tested formulations. These findings confirm the feasibility of blending TPU with modified phenolic resin.