Effect of Different Inorganic Fillers on the Physical and Mechanical Properties of Bisphenol‐A Epoxy Matrix

ABSTRACT This study presents a comprehensive investigation into the influence of various inorganic fillers—namely calcium carbonate (CaCO 3 ), wollastonite (CaSiO 3 ), aluminum (Al) powder, and titanium dioxide (TiO 2 )—on the mechanical, thermal, and morphological properties of a Bisphenol‐A‐based epoxy resin matrix. The primary objective of this study was to comparatively evaluate the extent of property enhancement imparted by each inorganic filler to the Bisphenol‐A epoxy matrix, to identify filler–performance relationships that can guide industry‐specific material selection and formulation. Despite extensive studies on epoxy–inorganic filler composites, most prior works have focused on single fillers, narrow concentration ranges, or isolated property evaluations, leaving a lack of systematic, side‐by‐side comparison under identical conditions. This study addresses this gap by evaluating these four industrially relevant fillers across a wide dosage range to establish their comparative influence on the mechanical, thermal, and morphological behavior of a Bisphenol‐A epoxy matrix. Each filler was incorporated into the epoxy matrix at 2.5–20 wt%, yielding distinct, filler‐specific property responses. Calcium carbonate produced the highest lap‐shear strength (13 MPa at 15 wt%), whereas wollastonite resulted in the greatest pot‐life extension (165 min at 15 wt%). Aluminum (Al) powder generated the maximum Shore‐D hardness (86.6 at 10 wt%) but was accompanied by a reduction in thermal resistance. In contrast, titanium dioxide consistently decreased pot‐life across all loadings. FTIR confirmed effective filler incorporation, while DSC showed a progressive increase in T g with increasing filler content. TGA results indicated enhanced thermal stability, particularly for CaCO 3 . SEM micrographs revealed uniform dispersion at optimal loadings and agglomeration at higher concentrations, consistent with observed mechanical trends.