Void Content Minimization in Vacuum Infusion (VI) via Effective Degassing

Area of Science:

• Materials Science
• Composite Manufacturing

Background:

• Component porosity is a critical issue in Vacuum Infusion (VI) manufacturing, particularly due to resin gelation under vacuum conditions.
• Effective degassing is essential to minimize resin outgassing and dissolve voids formed during preform impregnation.

Purpose of the Study:

• To analyze the efficacy of various degassing procedures on final void content in VI manufacturing.
• To isolate and study the effects of outgassing on void content by carefully controlling the manufacturing process.

Main Methods:

• Investigated vacuum degassing procedures, including the use of nucleation media, High-Speed (HS) resin stirring, and delayed pressurization.
• Manufactured specimens with distinct porosity regions to facilitate detailed analysis of void content.

Main Results:

• High-Speed (HS) resin stirring during degassing reduced porous area size by 72% compared to conventional vacuum degassing.
• Achieved a maximum void content below 4% through optimized degassing strategies.
• Demonstrated that enhancing bubble formation during degassing is crucial for reducing porosity.

Conclusions:

• Optimized degassing procedures, especially those enhancing bubble formation like HS resin stirring, are vital for minimizing porosity in VI composites.
• The study successfully isolated outgassing effects, providing clear insights into porosity reduction strategies.
• Achieving low void content (under 4%) is feasible with advanced degassing techniques.