What are the differences in elongation at break between polyethylene and PVC?

Polyethylene and PVC (polyvinyl chloride) are two of the most commonly used polymers in various industries, but they exhibit distinct mechanical properties, particularly in elongation at break. Elongation at break measures how much a material can stretch before it fractures, indicating its ductility.

Polyethylene, especially low-density polyethylene (LDPE), typically has a high elongation at break, ranging from 100% to 1000%, depending on the grade. This makes it highly flexible and resistant to cracking under stress. High-density polyethylene (HDPE) has lower elongation but still offers good ductility.

In contrast, PVC is generally more rigid, with elongation at break values between 20% and 400%, depending on whether it is plasticized (flexible PVC) or unplasticized (rigid PVC). Flexible PVC can stretch more due to added plasticizers, while rigid PVC is brittle and breaks at lower elongation.

The differences arise from their molecular structures: polyethylene has a simple, non-polar structure allowing chain mobility, while PVC's chlorine atoms create stronger intermolecular forces, reducing flexibility. These properties influence their applications, with polyethylene favored for packaging and PVC for pipes and rigid products.

Understanding these differences helps engineers select the right material for specific needs, balancing flexibility, strength, and durability.