Why is a laboratory vacuum degassing chamber necessary for bio-based epoxy? Eliminate Voids & Maximize Strength

A laboratory vacuum degassing chamber is essential for preserving the structural integrity of bio-based epoxy and graphene composites. During the preparation phase, mechanical stirring and ultrasonic dispersion inevitably entrap microscopic air bubbles within the resin system. If not removed via vacuum, these bubbles harden into permanent defects, significantly compromising the material's density and mechanical strength.

Core Takeaway: While mixing is required to disperse graphene, it creates a secondary problem by aerating the resin. Degassing is the critical corrective step that prevents these air pockets from becoming stress concentration points, ensuring the final composite achieves its maximum potential strength.

The Consequence of Processing

To understand the necessity of a vacuum chamber, one must look at how the composite is created.

The Side Effect of Dispersion

To create a high-quality mixture, researchers must use mechanical stirring and ultrasonic dispersion.

While these methods are effective at distributing graphene throughout the epoxy, they act as aeration mechanisms. They mechanically force air into the viscous resin, creating a suspension of microscopic bubbles that will not escape naturally before the resin cures.

From Bubbles to Microporous Defects

If the mixture is cured immediately after stirring, the trapped air is locked in place.

These bubbles transform into microporous defects within the solid composite. The result is a material that looks solid to the naked eye but is internally riddled with voids.

The Impact on Mechanical Performance

The presence of air bubbles is not merely a cosmetic issue; it is a structural liability.

Creating Stress Concentration Points

A uniform material distributes load evenly. However, microporous defects act as stress concentration points.

When the composite is placed under load, stress accumulates rapidly at these void sites rather than dispersing through the matrix. This leads to crack initiation and premature mechanical failure at loads far below the material's theoretical limit.

Ensuring Lap Shear Strength

Degassing is directly linked to the lap shear strength of the final product.

By removing the voids, the vacuum process ensures a continuous, solid matrix. This continuity is required to transfer stress effectively between the resin and the graphene reinforcement.

Maximizing Density

A composite full of air bubbles has a lower density than a solid composite.

To achieve consistent, reproducible density metrics, the air must be evacuated. This ensures that the measured properties reflect the true nature of the bio-based epoxy and graphene, rather than the volume of trapped air.

Understanding the Risks

Skipping or rushing the degassing phase introduces significant variables into your research.

The Illusion of Strength

Without degassing, a researcher might attribute a material failure to the bio-based resin or the graphene concentration.

In reality, the failure may be caused solely by the processing defect (air bubbles). This leads to incorrect conclusions about the material's viability.

Incomplete Evacuation

Simply applying a vacuum is sometimes not enough; the process must be thorough.

If the vacuum is insufficient, the smallest bubbles—often the most difficult to remove from viscous epoxy—will remain. These residual defects can still act as failure points, negating the effort put into the mixing process.

Making the Right Choice for Your Goal

To ensure your composite performs as intended, apply the following guidelines based on your specific objectives:

• If your primary focus is maximum durability: Ensure a complete vacuum cycle to eliminate stress concentration points and optimize lap shear strength.
• If your primary focus is fundamental research: Standardize your degassing procedure to prevent microporous defects from creating variable density data across your samples.

By rigorously removing entrapped air, you ensure that your composite's performance is defined by its chemistry, not its defects.

Summary Table:

Process Phase	Effect of Degassing	Impact on Final Composite
Post-Mixing	Removes entrapped air bubbles	Eliminates internal microporous defects
Curing	Creates a continuous solid matrix	Prevents crack-inducing stress points
Final Testing	Standardizes material density	Maximizes lap shear & mechanical strength

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Ensure your composites achieve their theoretical maximum strength. Contact KINTEK today to find the perfect degassing solution for your laboratory!

References

1. Sheikh Rehman, Panagiotis Karagiannidis. Βio-Based Epoxy/Amine Reinforced with Reduced Graphene Oxide (rGO) or GLYMO-rGO: Study of Curing Kinetics, Mechanical Properties, Lamination and Bonding Performance. DOI: 10.3390/nano12020222

This article is also based on technical information from Kintek Solution Knowledge Base .