Fabrication of (unsaturated polyester/eggshell fibers) composites as white natural gelcoat with high mechanical properties

To prepare an inexpensive gelcoat that has excellent mechanical properties, white eggshell powder of small particle size (∼300 nm) has been added with different weight fractions (1, 2, 3, 4, 5, 6, 7, and 8 %) to Unsaturated Polyester. The weight ratio (1%) of eggshell powder is the best ratio to be added to polyester to improve its mechanical properties such as hardness, impact strength, and wear resistance. 2% weight ratio of titanium dioxide was added to (polyester/ 1% eggshell powder) composite as a white color, as well as to get further improvements in mechanical properties of polyester, where the hardness was improved by (0.57%), impact strength improved by (∼8.6%) and the flexural strength by (78.6%). Wear resistance and thermal conductivity of (polyester +1% E.S+2% TiO2) Gelcoat are increased by (58.6%) and (17.5%) respectively, compared to its values for (polyester +2% eggshell+2% TiO2) Gelcoat. The images of electron microscope were used to observe the degree of homogeneity in polyester composite microstructure, which interpreted the results that are improved mechanically and thermally.