Melting behavior of poly(l-lactic acid): Effects of crystallization temperature and time

Isothermal cold crystallization and melting behaviors of poly(L‐lactic acid)s prepared by melt polycondensation

“…The high melting peak indicates the melting of the a crystals formed originally and/or after recrystallization. Figure 7 shows that the T mL changed in an interesting ''Z-shape'' manner rather than a discrete manner reported by Yasuniwa et al 9 It decreased suddenly in a narrow T c range (95 C-102 C) though it increased with T c in lower or higher T c range. So, the whole T c range for PLLA3 can be divided into Figure 7.…”

“…8,9 Trigonal b crystal and orthorhombic a crystal are formed at T c 's lower and higher than 113 C, respectively, and both crystals are formed simultaneously around 113 C. 8,9 So, the low and middle melting peaks result from the melting off b and a crystals formed during isothermal crystallization, respectively. The high melting peak indicates the melting of the a crystals formed originally and/or after recrystallization.…”

“…Therefore, it is widely researched and applied as commodity plastics, agricultural films, fibers, and biomaterials. [2][3][4] As its crystalline properties have significant influence on its physical and mechanical properties, 5 the researches on its crystalline structure, [6][7][8][9] morphology, 10 kinetics and spherulite growth, 7,9,11,12 and their effects on the melting behaviors 6,8,13,14 have been extensively reported. Most of such researches were based on PLLA prepared by ring opening polymerization (ROP) of L-lactide.…”

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).…”

Isothermal and nonisothermal crystallization kinetics of poly(ϵ‐caprolactone)

“…4 The crystallization behavior 4,5 and kinetics of polymeric materials have been reviewed previously. [6][7][8] In particular, the isothermal and nonisothermal crystallization kinetics of commodity and engineering polymers, such as isotactic polypropylene, [9][10][11][12] filled polypropylenes, 13,14 poly(ethylene terephthalate), 15,16 poly(trimethylene terephthalate), 17,18 poly(butylenes terephthalate), 19 nylon, [20][21][22] and poly(sulfides), [23][24][25] have been investigated in detail, and to much lesser extent, those of biopolymers, such as poly(lactic acid) [26][27][28][29] and poly(e-caprolactone) (PCL), [30][31][32][33] have been studied, although they have found wide commercial importance.…”