Enhanced thermal stability and impact strength of phenolic formaldehyde resin using acid-treated basalt scales

In this study, phenolic formaldehyde (PF) resin-based composites were prepared using basalt scale (BS) as a reinforcing agent via a melting-blending method. The BS surface was treated with hydrochloric acid, and the surface properties were characterized using thermal field-emission scanning electron microscopy, Fourier-transform infrared, X-ray photoelectron spectrometry, and energy-dispersive X-ray spectroscopy. Moreover, the influence of acid-treated BS (H-BS) content on the thermal properties, flexural properties, impact strength, and morphology of PF/H-BS composites was investigated. The thermal stability and glass transition temperature of the composites increased significantly with the increasing H-BS content. The impact strength tests indicated that the impact strength of the composite with 15 wt% H-BS was 0.66 kJ/m², which is 153% higher than that of pristine PF. The scanning electron microscopy results indicated that the PF/H-BS composites exhibit rough morphology with numerous microcracks.