Production and characterization of hybrid composites with orthophthalic polyester resin matrix

This study comprehensively analyzes the effects of adding pistachio shell and talc to an orthophthalic polyester resin matrix on the properties of polyester matrix hybrid composites. In the study, a total of six samples were prepared using different ratios of pistachio shell and talc fillers, both together and separately, with a total filler content of 40%, including pure polyester. The preparation process of the composites involves grinding the pistachio shells, classifying them dimensionally using a sieve machine, and producing test samples through the polymer casting method. Subsequently, the mechanical, thermal, surface gloss, and microstructural properties of the polyester matrix hybrid composites were characterized. Tensile and three-point bending tests showed that the addition of pistachio shell and talc significantly affects the stiffness and mechanical properties. The effect of talc on the mechanical properties of the composite is higher compared to pistachio shell. As the talc ratio increases in the mixture, tensile strength, tensile modulus, flexural strength, and flexural modulus also increase. Similar trends were observed in impact test results; however, the highest impact strength was obtained as 5.04±0.53 kJ/m² in the PESAW03 composite containing 30% pistachio shell and 10% talc. The hardness of the composites was found to be lower compared to pure polyester. Surface gloss measurements indicated that higher talc content makes the composite more matte. While the increase in pistachio shell content decreases the density, the increase in talc content increases the density of the composite. Thermal analysis results showed that talc content enhances the thermal stability of the composite, whereas pistachio shell slightly reduces this stability. Microstructural analyses demonstrated that the homogeneous distribution of talc within the composite enhances crack resistance, whereas pistachio shell causes density variations in certain areas. These findings emphasize that careful selection of filler material ratios is essential to optimize the performance of polyester matrix hybrid composites.