Mechanism of degradation induced embrittlement in polyethylene

The following embrittlement mechanism is proposed: chain scission in the amorphous phase induces chemicrystallization. The thickness of the interlamellar amorphous layer (la) decreases until a critical value of the order of 6-7 nm, below which plasticity cannot be activated and the polymer behaves in a brittle manner, as previously shown for virgin polyethylene. Using (la, MW) maps, it is possible to explain the differences observed in the embrittlement behaviour of semi-crystalline polymers predominantly undergoing chain scission.