Crystallization behavior of poly(l-lactic acid)

Application of Differential Scanning Calorimetry to the Characterization of Biopolymers

“…Some semi-crystalline polymers with the slow crystallization ability like poly(lactic acid) do not have time to crystallize during cooling and thus crystallize during 2 nd heating cycle (cold crystallization) and consequently the melting peak may appear as double peak due to the content of different kinds of crystals. The melting behaviour of PLA is complex with regard to its multiple melting behaviour and polymorphism and has been intensively studied by several authors (Yasiniwa et al, 2004;Yasuniwa et al, 2006;Yasuniwa et al, 2007;Di Lorenzo, 2006).…”

Amino acids and poly(amino acids) as nucleating agents for poly(lactic acid)

“…According to literature [8,9], the formed crystal structure at this T c is the α-form. To compare the effect of different agents, they were added at the same concentration: 1.5 wt%.…”

“…This phenomenon gives rise to a discontinuity in the typical bell-shaped curve where the characteristic crystallization time is plotted as a function of T c . Yasuniwa et al [9] explained it as a change in crystal structure from orthorhombic (α-form) to trigonal (β-form), formed at high and low T c s, respectively. Furthermore, Miyata and Masuko [10] and He et al [11] investigated the influence of PLA molecular weight on the isothermal crystallization behavior.…”

Crystallization Behaviors and Structure Transitions of Biocompatible and Biodegradable Diblock Copolymers

“…Furthermore, the morphologies formed at 130 °C are more regular, which are composed of six main branches, and the second branches grow along the main branches, the second branches along one main branch are parallel with each other, then the third branches grow in the same way as the second branches. The peculiar dendrite formed in high temperature range can be explained with nucleation, diffusion, growth, and their competition with each other and the addition of PEO block [7,44,48]. As shown in Figure 18, the morphologies of the diblock copolymer are crystallization temperature (T c ) dependent.…”

“…An interesting morphology of which the center is spherulite and the outer is dendrite was formed at T c = 115 °C shown in Figure 18d. When crystallized at a higher temperature, T c > 115 °C, the crystallization behavior and the crystalline morphologies are absolutely different from those at low T c [7,[44][45][46][47]. Dense dendrites were formed at 120 °C, as shown in Figure 18e,f; the morphologies composed by the main branches were star-shaped, and the second branches grew along the main branches.…”