What are the differences in thermal expansion between PVC and polyethylene?

Thermal expansion is a critical property in plastics, affecting their performance in various applications. PVC (Polyvinyl Chloride) and polyethylene are two widely used plastics with distinct thermal expansion behaviors.

PVC has a linear thermal expansion coefficient of approximately 50–80 x 10^-6 /°C, making it more dimensionally stable under temperature changes compared to polyethylene. Polyethylene, depending on its density (LDPE or HDPE), exhibits a higher thermal expansion coefficient, ranging from 100–200 x 10^-6 /°C. This means polyethylene expands more significantly when heated, which can impact its suitability for precision applications.

The differences arise from their molecular structures. PVC's rigid, polar structure resists expansion, while polyethylene's flexible, non-polar chains allow greater movement. Engineers must consider these properties when selecting materials for environments with temperature fluctuations.

Understanding these differences ensures optimal material choice for construction, packaging, and industrial uses where thermal stability is crucial.