Weatherability of Plastics: A Complete Guide

Key Takeaways

• Weatherability shows how well a material resists outdoor conditions.

• Plastics with low resistance can weaken over time, so proper selection is key.

• Acrylic, polycarbonate, PTFE, and PVC are highly durable, while super-engineering plastics offer maximum longevity at a higher cost.

Overview

Outdoor plastic parts can quickly discolor, crack, or degrade if the material wasn’t properly selected. The key to long-lasting performance is weatherability, a material’s ability to resist sunlight, rain, and temperature fluctuations.

This guide explains the main causes of plastic degradation and provides designers and engineers with practical guidance for choosing materials that ensure reliable outdoor performance over time.

Weather Resistance of Resins and Plastics

Weatherability measures how well a material withstands sunlight, heat, humidity, and rain without warping, fading, or degrading. Consider plastic clothespins as an example of low weatherability. They are inexpensive and easy to make, but when left outdoors for long periods, they often discolor and become brittle.

Main Causes of Degradation

1. Sunlight and ultraviolet (UV) radiation

2. Rainwater

3. Oxidation from exposure to air

4. Temperature fluctuations between day and night

If a product will be used outdoors, material weatherability is a critical consideration.

Testing Material Weatherability

Weatherability is often assessed through outdoor exposure tests, where samples are placed outside to observe real-world effects. Since these tests are time-consuming and are difficult to reproduce consistently, accelerated tests are often used to simulate sunlight, heat, and humidity to quickly estimate material lifespan. Combining both methods provides the most reliable results.

Plastics with Superior Weather Resistance

Materials with high weatherability include acrylic, polycarbonate, PTFE, and PVC. Each has distinct properties, so understanding these differences is key for proper selection.

Acrylic

Acrylic is extremely transparent, with a light transmittance of 93%, surpassing glass. It resists sunlight, rain, and other outdoor conditions, and it is also impact-resistant, reducing the risk of shattering. Acrylic can also be bonded with adhesives, making it suitable for applications such as signage, automotive lamp lenses, illuminated sign covers, aquariums, and catalog cases.

Polycarbonate

Polycarbonate has exceptionally high impact strength, even suitable for bullet-resistant applications. Like acrylic, it can be bonded with adhesives, and is commonly used in signage, illuminated signs, balcony and parking lot roofs, and highway noise barriers.

PVC

PVC is a widely-used, cost-effective plastic that resists most acids, alkalis, and salts, and it can be bonded or welded. PVC also offers high weather resistance, making it suitable for economical outdoor applications. Rigid PVC is used for pipes, ducts, and industrial water supply products, while flexible PVC is used in clothing, bags, and greenhouses. (Yumoto Electric processes only rigid PVC.)

PTFE (Teflon)

PTFE is a high-performance super-engineering plastic with excellent weather resistance, showing minimal degradation even with long-term outdoor use. It also has extremely high heat resistance and excellent wear resistance. PTFE is used both as a material and as a coating to improve self-lubrication and weather resistance, such as in non-stick cookware and membrane materials like membrane roofs. Its near-zero water absorption prevents water infiltration.

Plastic CNC Machining at Yumoto Electric

Yumoto Electric delivers high-quality components fast, worldwide. We provide precision machining for a wide range of engineering plastics, including PEEK, PPS, MC Nylon, and POM.

If you’re unsure about material selection or machining methods, we offer complimentary consultations to help optimize your design and production. For any questions, please feel free to contact us.