Experimental investigation for short glass fiber reinforced magnetically loaded polymer composites by compression molding on morphology and mechanical-magnetic properties

Polymer composites incorporating magnetic fillers offer great potential for applications in energy storage, biomedical devices, and electromechanical systems. To facilitate the design of such components, it is critical to understand the morphology, thermal, mechanical, and magnetic behavior of short glass fiber reinforced, magnetically loaded polymer (SFRMP) composites, which are inherently heterogeneous and potentially anisotropic. In this study, ternary composites consisting short glass fibers (SGFs), isotropic NdFeB magnetic particles, and a modified low-viscosity thermoset matrix were fabricated via compression molding at a total filler volume fraction of 50%, with magnetic particle contents ranging from 27.5 to 47.0% by volume. Microstructural characterization revealed preferential in-plane alignment of magnetic particles and partial planar orientation of SGFs. The elastic modulus increased with magnetic particles content, reaching 17.04 GPa for the highest particle loading, while thermal conductivity increased nonlinearly to 1.71 W/ (m·K), approximately 7.6 times higher than the neat matrix. Magnetic characterization confirmed directional dependence in remanence-to-saturation ratios, consistent with XRD analysis indicating slight preferential crystallographic orientation. This study demonstrates a scalable fabrication strategy for producing low-porosity, high-filler-density SFRMP composites with enhanced multifunctional performance.