Influence of melt processing conditions on poly(lactic acid) degradation: Molar mass distribution and crystallization

The influence of melt processing on the thermal behaviour of PLA was also investigated using temperature modulated differential scanning calorimetry (TMDSC). It was evidenced that the molar mass reduction affects the crystallizability of PLA. Cold crystallization temperature progressively decreases with decreasing molar mass and the metastable α' phase is formed in place of the stable α phase. The α′ phase can be partially converted into α form during melting giving rise to a double-melting peak. The two peaks can be separated using reversing and non-reversing signals confirming that recrystallization of the α′ form occurs.