Seawater-immersed glass-polyester composites with optimized mechanical properties

Area of Science:

• Materials Science
• Marine Engineering

Background:

• Composites offer excellent properties for marine applications but degrade with seawater exposure.
• Understanding composite degradation is vital for their longevity in marine environments.

Purpose of the Study:

• To investigate the effect of seawater immersion on the mechanical properties of glass fiber reinforced unsaturated polyester composites (CMPG).
• To evaluate how fiber configuration, areal density, and immersion time influence composite performance.
• To develop a predictive model for CMPG mechanical properties under marine conditions.

Main Methods:

• Tensile testing (EN ISO 527) on CMPG samples with varying fiber layers (1- and 3-layer) and areal densities (300–600 g/m²).
• Seawater immersion for 3, 21, and 30 days.
• Fourier Transform Infrared (FTIR) spectroscopy and dimensional swelling analysis.
• Multiple regression modeling and Analysis of Variance (ANOVA) for data analysis.

Main Results:

• Mechanical properties like maximum stress and tensile modulus decreased with increased seawater immersion time.
• 3-layer composites showed superior tensile strength compared to 1-layer.
• Higher fiber density (600 g/m²) composites absorbed less water and exhibited less swelling.
• Seawater immersion significantly impacted tensile performance (p < 0.01), causing chemical degradation.

Conclusions:

• CMPG composites are susceptible to degradation in marine environments, with immersion time being a critical factor.
• Material design (layering, fiber density) influences seawater resistance.
• Careful material selection and protective surface treatments are essential for durable marine applications of CMPG.