Which material is generally not recommended for use in outdoor applications?

In outdoor applications, materials are often evaluated based on their durability, weather resistance, and potential for corrosion. Plastic is generally not recommended for outdoor use because it can deteriorate when exposed to UV light from the sun, leading to brittleness and degradation over time. While it can be utilized in certain niche applications, its overall lack of robustness compared to metals makes it less suitable for widely used outdoor installations.

In contrast, aluminum, steel, and copper have properties that make them more favorable for outdoor use. Aluminum is lightweight and resistant to corrosion, making it a popular choice for outdoor applications. Steel, while susceptible to rust, can be treated to resist corrosion, and it has the strength that makes it viable for many outdoor structures. Copper is highly durable and also develops a protective patina that shields it from corrosion, thus making it suitable for various outdoor electrical applications. Therefore, plastic stands out as the least recommended choice for enduring outdoor conditions.