The effect of nano-gelcoat on freeze-thaw resistance of glass fiber-reinforced polymer composite for marine applications

Glass fiber-reinforced polymers and protective gelcoats are important construction materials used in marine structure engineering. This study focused on the effect of freeze-thaw test on the properties of glass fiber-reinforced epoxy composites coated with nano-gelcoat. Nanoclay and nano TiO2 (1, 2, 3 wt%) were used to prepare nano-gelcoat and applied to composite surfaces. After the 45 and 90 freeze-thaw cycles, the change in the mechanical properties of the composites was determined and the thermal stability of the coatings was investigated. Mechanical features were investigated by tensile, flexural, short beam and compression tests. The thermal stability of the gelcoats was determined using Differential thermal analysis (DTA) and Thermogravi-metric analysis (TGA). The morphology of the coatings was investigated by SEM (Scanning electron microscope). Water absorption properties were tested in hydrothermal environment. Finally, a statistical analysis, ANOVA (Analysis of variance), was conducted to determine whether the experimental results were significant or not. Nano TiO2 improved the water absorption property by 15.09% and preserved the mechanical properties by up to 8.8% compared to pure gelcoat. Nano TiO2 increased the melting temperature from 224.46 degrees C to 261.59 degrees C and provided a 16.54% improvement and also increased the decomposition temperature. Since the thermal con-ductivity of nanoclay is higher than nano TiO2, the nanoclay contribution increased this value by 7.14% and the nano TiO2 contribution by 3.57%. However, nanoclay has reduced the protection property of pure gelcoat due to its shape and size disadvantages. ANOVA analysis also revealed that the results were statistically significant.

Automated summary

This study investigated the effects of freeze-thaw test on glass fiber-reinforced epoxy composite coatings with nano-gelcoat. The mechanical properties and thermal stability of the coatings were examined through various tests and analyses. Results showed that the addition of nano TiO2 improved water absorption property and preserved mechanical properties. However, the presence of nanoclay reduced the protection property of the pure gelcoat. Statistical analysis confirmed the significance of the experimental results.