How does the environmental stress crack resistance (ESCR) of polyethylene vary by grade?

The environmental stress crack resistance (ESCR) of polyethylene varies significantly depending on the grade of the polymer. High-density polyethylene (HDPE) generally exhibits higher ESCR compared to low-density polyethylene (LDPE) due to its more linear molecular structure and higher crystallinity. HDPE's resistance to cracking under stress makes it ideal for applications like piping and containers. In contrast, LDPE, with its branched structure, has lower ESCR but offers greater flexibility. Additionally, medium-density polyethylene (MDPE) and linear low-density polyethylene (LLDPE) fall between these extremes, balancing flexibility and crack resistance. Factors such as molecular weight, additives, and processing conditions also influence ESCR performance across different polyethylene grades.