How Retting Could Affect the Mechanical Behavior of Flax/Epoxy Biocomposite Materials?

Area of Science:

• Materials Science
• Biomaterials Engineering
• Textile Science

Background:

• Flax fibers are crucial for biobased materials.
• Understanding retting's impact on flax fiber properties is essential for optimizing biocomposite performance.
• Previous research has explored flax fiber processing, but a detailed analysis of retting's biochemical and mechanical effects on both fibers and resultant biocomposites is needed.

Purpose of the Study:

• To investigate the effect of retting on the mechanical properties of flax biobased materials.
• To establish a link between the biochemical alterations of flax fibers during retting and their mechanical performance.
• To analyze the mechanical behavior of flax biocomposites produced via thermocompression as a function of retting level.

Main Methods:

• Technical flax fibers were subjected to varying retting levels.
• Biochemical analysis was performed to quantify changes in soluble and holocellulose fractions.
• Mechanical testing (ultimate modulus, maximum stress, Young's moduli) was conducted on both individual fibers and thermocompressed biocomposites.
• Biocomposite porosity (Vp) and fiber fraction (Vf) were analyzed.

Main Results:

• Retting led to smoother, more individualized flax fibers but decreased ultimate modulus and maximum stress.
• Biochemical analysis showed a decrease in soluble fractions and an increase in holocellulose fractions with increased retting.
• Biocomposites exhibited non-elastic behavior; Young's moduli (E1 and E2) increased with retting.
• Normalization revealed a 40% increase in elastic modulus between under-retted and over-retted flax.
• Porosity content (Vp) generally increased with fiber content, with Setup 3 showing optimal processing.

Conclusions:

• Retting significantly influences the biochemical composition and mechanical properties of flax fibers.
• The retting level directly affects the mechanical performance of flax biocomposites, with higher retting potentially increasing stiffness.
• Optimized processing parameters (Setup 3) are crucial for maximizing fiber fraction while minimizing porosity in flax biocomposites.