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. Author manuscript; available in PMC: 2022 Jul 27.
Published in final edited form as: J Mater Res Technol. 2021 Nov 20;15:6356–6366. doi: 10.1016/j.jmrt.2021.11.048

Table 1.

Various PLA crystalline phases regarding their unit cell parameters, their chains conformation state, and formation condition.

Crystalline
phase		 Unit cell Conformation Formation condition
α Orthorhombic a = 9.95 °A, b = 6.25 °A, c = 8.8 °A 103 left-handed helix Crystalizes above 120 °c
α′ Pseudo-hexagonal a = b = 6.2 °A, c = 28.8 °A 103 distorted helix Crystalizes below 120 °c
β Trigonal a = b = 10.52 °A, c = 8.8 °A 31 left-handed helix with frustrated structure Drawing ratio ≥6 T ≈ Tmelting
γ Orthorhombic a = 9.95 °A, b = 6.25 °A, c = 8.8 °A 31 antiparallel left-handed helix Epitaxial crystallization on hexamethylbenzene (HBM) substrate