Why Phenolic Prepregs Are Finding Their Way Into Marine Construction

As a class of composite materials, phenolic prepregs are considered high-performance composites capable of holding up under extreme stresses. They represent a strong alternative to traditional resin systems – like epoxy and polyester – in both structural and non-structural components.

They are gradually finding their way into marine construction thanks to their fire safety capabilities and exceptional corrosion resistance. Both are non-negotiable in marine environments.

The Basics of Phenolic Prepregs

A phenolic prepreg is an advanced type of pre-impregnated composite material. Standard prepregs are engineered by combining a fiber reinforcement like carbon, glass, or aramid fibers with a resin matrix. A phenolic prepreg is similar except that the matrix is a phenolic resin.

For the record, a phenolic resin is created through a reaction between phenol and formaldehyde. Its chemical structure and properties make it ideal for applications requiring high thermal stability, fire resistance, and exceptional mechanical strength.

Getting back to the phenolic prepreg, it is fully saturated with resin during the manufacturing process. The resin is partially cured prior to shipping, making the prepreg easier to handle. However, the prepreg still requires heat and pressure to fully cure. Autoclave curing is the best method.

Advantages to Marine Construction

There are still plenty of applications for epoxy resins in marine construction. Engineers still rely on them for manufacturing common components like high-performance hulls. But phenolic prepregs bring some unique properties to the table, properties that are very desirable for certain types of marine vessels.

1. Fire, Smoke, and Toxicity (FST)

Exceptional FST performance is the single greatest advantage phenolic prepregs have over those made with epoxy and polyester resins. Phenolic resins are inherently fire resistant. They do not burn easily.

Should a fire break out, phenolic resins generate minimal smoke and toxic fumes. Think of the implications for a passenger ferry where escape time and overall passenger safety are critically important.

2. Corrosion and Chemical Resistance

Composites made with phenolic resins are exceptionally resistant to a variety of harsh chemicals and solvents. More importantly, they are fully resistant to corrosion. Saltwater and constant marine environment moisture have little to no effect on phenolic composites.

3. High Strength-to-Weight Ratio

Like all composites, phenolic prepregs offer a high strength-to-weight ratio. And by precisely controlling resin content, designers can optimize the fiber-to-resin ratio for the purposes of achieving specific mechanical properties.

As a result, marine structures can be engineered with low density but still be strong and stiff. Balancing strength and stiffness with weight reduces fuel consumption while increasing efficiency and speed.

4. Dimensional Stability

Dimensional stability is non-negotiable in marine construction. Vessels must maintain their strength and integrity despite temperature changes, challenging marine environments, and the normal effects of time. Phenolic resins are up to the task. They contribute to excellent dimensional stability throughout a vessel’s lifetime.

Marine Applications for Phenolic Prepregs

Engineers specializing in marine design appreciate all the benefits phenolic prepregs have to offer. They rely on phenolic prepregs primarily for internal and secondary structures. Examples include:

• Interior panels (e.g., walls, ceilings, partition panels, bulkheads, etc.)
• Decks and walkways (especially where fire and slip-resistant surfaces are required)
• Superstructures (especially composite elements above the main deck)
• Honeycomb sandwich panels (face sheets and other internal structural elements)
• Pipes and conduit (e.g., deluge pipes, cable raceways, etc.)

Phenolic prepregs have become the material of choice in marine construction, especially for structural component applications where fire safety and low weight are top concerns. Axiom Materials deals in phenolic prepregs along with other composites that make modern marine construction what it is. Contact us to learn more.