Year-end Sale % OFF 
Abstract
PLA is well known to exhibit a low degree of crystallinity and slow crystallization kinetics. It is also a polymorphic material with two slightly different crystalline phases named α and α’. This work aimed at investigating the effect of PLA crystalline phases on the kinetics of crystallization, by means of a simple, telling and expedient technique, known as self-nucleation. To achieve this purpose, PLA samples were first crystallized at various temperatures to change the mix in the α and α’ phases. The samples were then partially melted by increasing the temperature near the melting temperature and then crystallized again upon cooling to examine the effect of the α and α’ crystal remnants on the non-isothermal crystallization behavior. A double crystallization peak was clearly evidenced for self-nucleated PLA samples indicative of the different crystallization efficiency of the two PLA phases using a specific thermal protocol. Thermal analysis, XRD and optical microscopy were combined to examine the effect of cooling rate and holding time at a given partial melting temperature on the ratio between the two observed crystallization peaks. Moreover, effect of molecular weight of PLA on the crystallization kinetics and the self-nucleation of PLA was investigated. The self-nucleation experiments revealed that the low and high-molecular weight PLA exhibited the highest non-isothermal crystallization temperature, Tcmax, equal to 160 °C for the samples isothermally crystallized in the range of temperature between 80 and 130 °C. Although for the high-molecular weight PLA Tcmax was a function of the original crystalline phase as well as the phase transition mechanism, for the low-molecular weight PLA, it was constant regardless of what the initial crystalline phase was. Based on crystallization and melting enthalpies, the proportion of the α and α’ phases was quantified using deconvolution analysis.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
