Hygrothermal Durability and Damage Evolution of Bio-Epoxy-Based Composites Reinforced with Different Fibre Types

Area of Science:

• Materials Science
• Polymer Science
• Composite Materials

Background:

• Bio-epoxy composites are explored as sustainable alternatives.
• Understanding hygrothermal durability is crucial for performance-critical applications.

Purpose of the Study:

• To investigate the hygrothermal durability of bio-epoxy composites reinforced with carbon, E-glass, basalt, and flax fibers.
• To assess the impact of hygrothermal aging on fiber and interfacial properties.
• To elucidate damage mechanisms in these composites.

Main Methods:

• Exposure of fiber yarns and composites to 60°C and 98% relative humidity for 3000 hours.
• Assessment of tensile strength reduction in fibers and interfacial shear strength (IFSS) reduction in composites.
• Chemical analysis using Energy-Dispersive X-ray Spectroscopy (EDS) and morphological examination using Scanning Electron Microscopy (SEM).

Main Results:

• Fiber type significantly influences durability; flax fibers showed better resistance to chemical degradation than synthetic fibers.
• Tensile strength reduction was higher in carbon, glass, and basalt fibers due to sizing layer degradation.
• IFSS reduction was highest in flax composites (10%) and lowest in carbon composites (4%).
• EDS revealed hydrolysis and erosion of sizing, and reduced silica in glass/basalt fibers.
• SEM showed varied failure modes: matrix-dominated in carbon, interfacial debonding in glass/basalt, and fiber pull-out in flax composites.

Conclusions:

• Bio-epoxy composites demonstrate acceptable performance under hygrothermal aging.
• Flax-reinforced bio-epoxy composites exhibit promising durability characteristics.
• The study highlights damage pathways and supports the potential of bio-epoxy composites as sustainable materials.