Influence of calcium carbonate fillers on pine fiber reinforced polyester composites

In the current work, the influence of calcium carbonate (CaCO₃) filler loadings on the physical, mechanical, thermal, and morphological properties of pine fiber (PF) reinforced polyester composites were analyzed. The fillers loaded PF/polyester composites were fabricated using casting technique. The results revealed that the volume percentage voids in the filler-loaded composites was less as compared to neat PF/polyester composites due to filler occupancy in the air gaps of fabricated composites. The tensile strength increment in neat PF reinforced composites (10–30 vol%) was prompted by the polyester's ability to wet PF perfectly thereby building a good and dense interfacial bond between the polyester and PFs. However, the elastic modulus and elongation values were higher for filler-loaded PF/polyester composite (PF3/CCP10). The composite PF3/CCP10 also exhibited maximum flexural and impact strengths due to the ability of filler particles to support the stress transfer between matrix and fiber, also the strong interfacial bonding due to the chemical treatment of PFs. The fillers-loaded composites exhibited an acceptable hardness value due to the resistance of filler particles against indentation force towards deformation. Fillers improved the thermal resistance of PF reinforced polyester composites, especially the PF3/CCP10 composite having a maximum amount of filers loading. Scanning electron microscopy morphological analysis reveals the strong interfacial adhesion in filler-based composites with lower void contents, resulting in superior adhesion characteristics between fibers and polyester matrix.