Polyvinyl Chloride (PVC)

Polyvinyl Chloride (PVC), a versatile thermoplastic made from vinyl chloride monomers, is utilized in aviation for its durability, flame resistance, and cost-effectiveness.

Background and Evolution

PVC was first synthesized in the 1870s and commercialized in the 1930s by companies like BFGoodrich, initially for industrial piping. Its aviation use began in the 1950s with aircraft like the Boeing 707, where it insulated wiring and ducted air. It remains a practical choice in modern planes like the Airbus A320, enhanced with additives for safety standards.

How PVC is Used

PVC, a rigid or flexible plastic varying in color, is processed into:

• Wire Insulation: Coats electrical wiring and cables, protecting against shorts and wear.
• Ducting: Forms lightweight air vents and conduits for cabin ventilation systems.
• Interior Trim: Shapes minor fittings like edge guards or panel linings, resisting abrasion.
• Piping: Used in low-pressure water or waste lines in galleys and lavatories.

Why PVC is Used

• Flame Resistance: Additives (e.g., plasticizers) meet FAR 25.853, reducing fire risk in electrical and interior roles.
• Lightweight: At 1.38 g/cm³, lighter than metals, aiding fuel efficiency in non-structural parts.
• Durability: Resists moisture, chemicals, and wear, ensuring long-term performance.
• Electrical Insulation: High dielectric strength (~20 kV/mm) prevents shorts in wiring.
• Cost-Effectiveness: Inexpensive to produce and process, ideal for widespread, non-critical use.

Technical Specifications

• Density: 1.38 g/cm³ (unplasticized), varies with additives.
• Melting Point: ~100–260°C (softens), depending on formulation.
• Hardness: 70–100 Shore D, durable yet flexible with plasticizers.
• Flammability: Self-extinguishing with proper additives.

Comparison to Alternative Materials

• PTFE: Superior heat resistance and insulation, but costlier and harder to process.
• ABS: Stronger and more impact-resistant, but less flame-retardant without additives.
• Polyethylene: Lighter (0.95 g/cm³) and flexible, but less durable and fire-resistant.
• Copper: Better conductivity for wiring, but heavier (8.9 g/cm³) and costlier.

PVC balances cost, safety, and utility.

Role in Modern Aviation

In aircraft like the Boeing 737 and Airbus A350, PVC insulates miles of wiring and shapes ducting, ensuring reliable electrical and air systems. It complements PTFE in high-heat zones and ABS in structural interiors, as seen in the Boeing 787 Dreamliner.

Environmental and Economic Considerations

• Production: Energy-efficient extrusion, though chlorine content raises environmental concerns.
• Cost: Among the cheapest plastics, widely accessible.
• Recycling: Recyclable, but aviation-grade additives complicate reuse.

Future Trends

Flame-retardant, eco-friendly PVC blends could sustain its use, though thermoplastics like PEEK may reduce its role in high-performance areas as sustainability pressures grow.

Summary

PVC’s flame resistance, durability, and affordability make it a key plastic in aviation’s wiring, ducting, and trim. Since the 1950s, it has supported reliable systems, retaining utility amid advanced material options.