How do expansion and contraction rates of PVC compare to polyethylene in outdoor temperature cycles?

PVC (Polyvinyl Chloride) and polyethylene are widely used plastics in outdoor applications, but their responses to temperature fluctuations differ significantly. PVC has a higher coefficient of thermal expansion (approximately 50-70 x 10^-6 per °C) compared to polyethylene (around 100-200 x 10^-6 per °C), meaning polyethylene expands and contracts more under temperature changes. This makes PVC more dimensionally stable in environments with frequent temperature cycles, such as outdoor construction or piping systems. However, polyethylene's flexibility can better accommodate stress from expansion without cracking. Engineers must consider these differences when selecting materials for long-term outdoor use to ensure durability and performance. Proper joint design and installation techniques can mitigate issues caused by thermal movement in both materials.