When selecting plastics for outdoor applications, their performance in extreme weather conditions becomes a critical consideration. The durability and lifespan of plastic materials under the stress of varying temperatures, UV exposure, precipitation, and wind can vary significantly.
Understanding the properties and limitations of different plastics is essential for making informed choices for outdoor uses.
UV Resistance and Thermal Stability
Polymers react to UV light and temperature changes in diverse ways. Extended exposure to sunlight can cause many plastics to degrade, losing colour and strength over time. UV stabilisers are often added to plastics to improve their resistance to sun damage.
Acrylic, also known as polymethyl methacrylate (PMMA), offers excellent clarity and UV resistance, making it suitable for outdoor glazing applications. It retains its properties and appearance for years, even under direct sunlight. However, it can become brittle in extremely cold temperatures.
Polyethylene (PE) and polypropylene (PP), commonly used in outdoor furniture and playground equipment, also exhibit good resistance to UV radiation. These materials can withstand a wide range of temperatures and are less likely to crack in cold weather.
Impact Resistance
In regions prone to hail or debris carried by high winds, impact resistance becomes a critical factor.
Polycarbonate is renowned for its high impact resistance and is often used in applications where a material must withstand blows without breaking, such as in riot shields and bulletproof glass. It maintains its integrity in harsh weather, though it is more prone to scratching than some other plastics.
Chemical Resistance and Water Absorption
Plastics like PVC (polyvinyl chloride) and polyethylene terephthalate (PET) are highly resistant to a wide range of chemicals, which is particularly important in areas with high pollution or salt spray from coastal environments. They also have low water absorption rates, which prevents them from swelling and losing structural integrity.
Expansion and Contraction
All materials expand and contract with temperature changes, but plastics exhibit a higher coefficient of thermal expansion than metals or glass. Nylon, for example, can absorb moisture and expand or contract significantly with temperature fluctuations, which may lead to dimensional instability in some applications.
Conversely, ABS (acrylonitrile butadiene styrene) has a lower coefficient of thermal expansion and is preferred for components that require dimensional stability across a range of temperatures.
Performance in Cold Climates
In cold climates, the brittleness of plastic is a major concern. PVC, for instance, can become brittle at sub-zero temperatures. In these environments, plastics like acetal (polyoxymethylene, POM) are favoured due to their high strength, stiffness, and excellent resistance to creep, even at low temperatures.
Longevity and Maintenance
The longevity of plastics is not only dependent on their inherent properties but also on maintenance and environmental factors. Simply Plastics can often provide guidance on the right type of plastic for specific environmental conditions, ensuring that maintenance is kept to a minimum while longevity is maximised. Kick-it plastic shed has low maintenance costs and is durable.
Polystyrene (PS) and polyvinyl chloride (PVC) are low-cost options for outdoor applications but may not perform well over long periods compared to other plastics, requiring more frequent replacement or maintenance.
Eco-Friendly Considerations
The environmental impact of plastics is a growing concern. Many plastics are not biodegradable and can cause significant pollution. However, some newer plastics and composites are designed to be more eco-friendly, breaking down more easily at the end of their life cycle without releasing harmful substances.
Conclusion
The choice of plastic for harsh weather conditions depends on a variety of factors, including UV resistance, impact strength, chemical and water resistance, thermal stability, and eco-friendliness.
Industry experts like Simply Plastics can provide valuable insights into the best materials for specific conditions, balancing performance requirements with sustainability concerns.
By carefully selecting the right type of plastic, one can ensure that structures and products remain functional and aesthetically pleasing for years to come, even in the face of nature’s extremes.