Preventing Defects in Thermoset Composites With Air Release Additives

Thermoset composites are created by combining a thermoset polymer (resin) and a reinforcing fiber, like glass or carbon fiber, together in a formulation or via various manufacturing processes. After being cured, thermoset composites provide exceptional strength-to-weight performance; fillers and pigments can also be added to provide additional properties, such as fire retardancy, lightweighting, and coloring.

Because thermoset resins are highly viscous and are typically applied in high wet film thickness, air bubbles becoming entrapped is common. The problem with air bubbles is that they become pinholes once cured and can lead to increased porosity and defects in the composite, which then leads to a reduction in overall performance in the final part. If performance is compromised, the result can be additional costs and potential safety hazards for the end user.

When produced without pinhole defects, thermoset composites can outperform metal and other materials in a variety of settings and are desired for many types of applications because of their high strength-to-weight and resistance to heat, corrosion, and moisture.

Removing Air Bubbles

One solution to remove micro and macro air bubbles is to make the thermoset composite under vacuum to pre-release the air, or to employ a processing or engineering solution. A more practical and less costly option is to use air release additives in the formulation process.

Air release additives – a.k.a. air release or de-aeration agents – help deter pinhole defects in composite materials. They can also prevent blisters in gelcoats, surface imperfections and poor appearance.

How do air release additives work? They rely on the principle of Stokes’ law, whereby larger air bubbles rise faster than smaller air bubbles. If small bubbles can be made to collide, the result is a coalescence of bubbles into larger bubbles that rise to the surface for more effective air release. The incompatibility of the air release agent leads to a concentrated level at the resin/ bubble interface. If two bubbles approach, the air release agent layers fuse due to their incompatibility with the resin and the bubbles coalescence.

Solplus™ F-Series Air Release Agents

Lubrizol offers advanced de-aeration polymers for thermoset resins that are created for the removal of air bubbles. Solplus™ F-Series air release agents promote the coalescence of smaller air bubbles to form larger bubbles that migrate to the surface to be released prior to curing. Solplus™ F-Series air release agents are based on unique technology for rapid air release and effective wetting and have grades suitable for unsaturated polyester, epoxy and vinyl ester thermoset applications.

Solplus™ F-Series for Effective De-Aeration

Contact Lubrizol to learn more about Solplus F-Series Air Release Additives or to request a product sample.

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