Amorphous minimum cooling rate

There is one characteristic that heavily limits the use of PLLA for commercial applications and that is the low crystallization rate. This results in a mostly amorphous product after processing. The minimum crystallization half time, t, for pure PLLA is of the order of several minutes, this is an extremely long time since the cooling time after the general processing methods is around 1 s. It has been described that the mechanical properties and degradation kinetics of the semi-crystalline PLLA are different from those of completely amorphous PDLLA. Mechanical and thermal properties of PLLA become almost constant when its molecular weight is above a threshold value of 70,000 Da (10). 

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