Journal ArticleDOI
Polymorphous Crystallization and Multiple Melting Behavior of Poly(l-lactide): Molecular Weight Dependence
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TLDR
In this article, the effect of molecular weight (MW) on the polymorphous crystallization and melting behavior of poly(l-lactide) were systemically studied by differential scanning calorimetry (DSC), polarized optical microscopy (POM), wide-angle X-ray diffraction (WAXD), and time-resolved Fourier transform infrared (FTIR) spectroscopy.Abstract:
The effect of molecular weight (MW) on the polymorphous crystallization and melting behavior of poly(l-lactide) (PLLA) were systemically studied by differential scanning calorimetry (DSC), polarized optical microscopy (POM), wide-angle X-ray diffraction (WAXD), and time-resolved Fourier transform infrared (FTIR) spectroscopy. It was found that the polymorphism of PLLA is not influenced much by MW, and the α‘- and α-form crystals are produced at low and high crystallization temperature (Tc), respectively, regardless of the MW. However, MW significantly affects the crystallization kinetics, and the crystallization rate reduces greatly with MW increasing. Moreover, the Tc- and MW-dependent melting behavior of PLLA was clarified with combining the DSC and FTIR results. It was found that the α‘- to α-crystalline phase transition occurs prior to the dominant melting in both the low- and high-MW PLLA crystallized at low Tc. Unlike the high-MW PLLA, in low-MW PLLA crystallized at low Tc, the α‘-form crystals only...read more
Citations
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Poly(lactic acid) crystallization
TL;DR: An overview of the current understanding on the fundamentals of PLA crystallization in quiescent conditions and on the practical means to enhance its rate can be found in this paper, where the most promising efforts in enhancing PLA crystallisation kinetics through plasticization or heterogeneous nucleation are reviewed.
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Polymorphism and isomorphism in biodegradable polyesters
Pengju Pan,Yoshio Inoue +1 more
TL;DR: A comprehensive review of the current understanding on (i) polymorphic crystallization and phase transition of biodegradable polyesters, (ii) isomorphic crystallization of poly(3-hydroxybutyrate) and (iii) poly(butylene adipate) random copolyesters, where the effects of comonomer composition and crystallization conditions are highlighted.
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From interfacial ring-opening polymerization to melt processing of cellulose nanowhisker-filled polylactide-based nanocomposites.
Anne-Lise Goffin,Jean-Marie Raquez,Emmanuel Duquesne,Gilberto Siqueira,Youssef Habibi,Youssef Habibi,Alain Dufresne,Philippe Dubois +7 more
TL;DR: It was clearly evidenced that the chemical grafting of CNW enhances their compatibility with the polymeric matrix and thus improves the final properties of the nanocomposites.
Journal ArticleDOI
Polymorphic Transition in Disordered Poly(l-lactide) Crystals Induced by Annealing at Elevated Temperatures
TL;DR: In this article, the effects of annealing conditions and molecular weight on the crystalline phase transition in poly(l-lactide) (PLLA) were studied by wide-angle X-ray diffraction (WAXD), Fourier transform infrared (FTIR) spectroscopy, and differential scanning calorimetry (DSC).
Journal ArticleDOI
Isothermal Crystallization of Poly(l-lactide) Induced by Graphene Nanosheets and Carbon Nanotubes: A Comparative Study
TL;DR: In this paper, the effects of differently dimensional nanoparticles on the crystallization behavior of poly(l-lactide) matrices were investigated using time-resolved Fourier transform infrared spectroscopy (FTIR) and wide-angle X-ray diffraction (WAXD).
References
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Journal ArticleDOI
Polylactic Acid Technology
TL;DR: Polylactic acid is proving to be a viable alternative to petrochemical-based plastics for many applications It is produced from renewable resources and is biodegradable, decomposing to give H2O, CO2, and humus, the black material in soil as mentioned in this paper.
Journal ArticleDOI
Melting process and the equilibrium melting temperature of polychlorotrifluoroethylene
John D. Hoffman,James J. Weeks +1 more
TL;DR: In this paper, a new method of estimating the equilibrium melting temperature, Tm, of a polymer is described, and applied to polychlorotrifluoroethylene (PCTFE), where the data fit a straight line of positive slope on a Ti (obs) versus Tx plot, Tx being the abscissa.
Journal ArticleDOI
Crystal structure, conformation and morphology of solution-spun poly(L-lactide) fibers
TL;DR: In this article, two crystal structures for solution-spun poly(L-lactide) are obtained: the pseudoorthorhombic α structure (a = 10.6, b = 6.1, and c = 28.8 A) is found at relatively low drawing temperatures and/or low hot-draw ratios.
Journal ArticleDOI
Crystal modifications and thermal behavior of poly(L-lactic acid) revealed by infrared spectroscopy
TL;DR: In this paper, a new crystal modification named the α form was proposed for the crystal structure of poly(l-lactic acid) samples annealed at temperature below 120 °C.
Journal ArticleDOI
The glass temperature and related properties of polystyrene. Influence of molecular weight
T. G. Fox,Paul J. Flory +1 more
TL;DR: In this article, the authors re-examined the previously reported empirical equations relating the above properties to molecular weight and temperature are re-expressed in terms of a revised molecular weight scale.