Brittleness and Brittle Temperature

Brittle temperature is very closely related to the and determines the minimum temperature at which a semi-crystalline polymer could be used without significant loss of its impact properties. According to ASTM D746 [31], the brittle temperature of LDPE is -156 C and that of HDPE lies between -156 and -73 C (brittleness temperature for HDPE is -70 C), which explains the good performance at low temperatures. 

At low temperatures, all plastics tend to become rigid and brittle, because the mobility of chains is greatly reduced. Impact strength at lower temperatures, e.g., 0 °C, can be considered as a useful criterion for material selection for use under artic conditions. Brittle temperature is close related to and is defined as the temperature at which 50% of specimens exhibit brittle failure under specified impact conditions. LDPE and HDPE have lower brittle temperature compared with other plastics [32]. 

---