Basalt Fiber Surface Modification for Improved Interaction With Polyamide‐6 for High‐Performance Automotive Applications

ABSTRACT

Basalt fiber‐reinforced polymer (BFRP) composites have emerged as sustainable alternatives to glass fiber (GF) composites, but their performance is often controlled by the quality of the fiber–matrix adhesion. Interfacial adhesion between reinforcing fiber and polymer matrix plays a pivotal role in improving the mechanical and thermal behavior of the composite materials. In this study, basalt fibers (BFs) were surface‐functionalized with mono‐amino silane (MAS), di‐amino silane (DAS), and tri‐amino silane (TAS) coupling agents to enhance compatibility and interfacial adhesion with polyamide‐6 (PA6, nylon 6). Short BFs (30 wt.%) were compounded with PA6 via twin‐screw extrusion and injection molded, and the resulting composites were systematically characterized using Fourier‐transform infrared spectroscopy, scanning electron microscopy‐energy dispersive X‐ray spectroscopy, tensile, flexural, impact, and heat deflection temperature (HDT) analyses. The silane treatments largely improved interfacial bonding, with tensile strength rising from 59.1 MPa for unsized BF‐PA6 to 138.4 MPa for TAS modified BF‐PA6, outperforming GF‐reinforced PA6 tensile strength. Enhanced adhesion was further supported by increased nitrogen incorporation, superior fiber length retention, and reduced fiber pull‐out in fracture surfaces. Thermal performance also improved, as HDT increased from 166°C in neat PA6 to 194°C in TAS BF‐PA6. The results demonstrate that amino‐silane functionalization, particularly TAS, provides a robust interphase, enabling BFs to serve as sustainable reinforcements for high‐performance thermoplastic composites in demanding automotive applications.