Login | Register

Nucleation and crystallization of poly(lactic acid)


Nucleation and crystallization of poly(lactic acid)

Yuryev, Yury (2011) Nucleation and crystallization of poly(lactic acid). PhD thesis, Concordia University.

[thumbnail of Yury_Yuryev_PhD_thesis_final_submission.pdf]
Text (application/pdf)
Yury_Yuryev_PhD_thesis_final_submission.pdf - Accepted Version


Poly(lactic acid) is one of the most promising “green” polymers, having huge potential for use as a packaging and construction material. The lack of knowledge about polylactide-specific crystallization behaviour is one of the barriers to widespread industrial use.
In the present thesis, different aspects of one of the most important phenomena in polylactide crystallization were studied. In the series of articles included in this thesis, parameters of quiescent and field-induced crystallization were investigated. Significant attention was paid to the spherulitic morphology, growth rates, and stereocomplexation phenomenon that are intrinsic to polylactide, due its optical activity. A novel technique for growth rate measurements based on ultrafast heating and cooling of cast films, was suggested and validated.
Melt crystallization of polylactide was studied using rheological methods. A new advanced model allowing the relation of complex viscosity to melt crystallinity was proposed and verified. The physical cross-linking phenomenon was introduced and quantified in the frame of the proposed model. Also, a new technique allowing the determination of the induction time of crystallization was presented and successfully validated. A proposed technique allowed dramatically improved precision of the measurement of induction time for both quiescent and field-induced crystallization.
The phenomena of surface crystallization that had previously gone unexamined by the research community were investigated in detail. A theoretical model was suggested and its predictions were supported by extensive computer simulations. The simulation program used for research was developed during this study. It was found that surface crystallization can have an immense effect on crystallization kinetics and dramatically distort the observed thermal analysis results. Custom-designed experiments allowed the application of these results to polylactide crystallization.
Extensive studies of shear-induced crystallization were done in this work. The novel techniques developed in the research allowed for a better understanding of the field-induced phenomenon. New techniques allowing the implementation of rheological measurements to discover and quantitatively assess electric field-induced polylactide crystallization were investigated in this study as well. It was shown that a DC electric field significantly promotes homogeneous nucleation of polylactide and enhances crystallization. An explanation to this observation based on the dipole moments of repeat units in the polylactide chain was offered and validated.

Divisions:Concordia University > Gina Cody School of Engineering and Computer Science > Mechanical and Industrial Engineering
Item Type:Thesis (PhD)
Authors:Yuryev, Yury
Institution:Concordia University
Degree Name:Ph. D.
Program:Mechanical Engineering
Date:16 December 2011
Thesis Supervisor(s):Wood-Adams, Paula
ID Code:974024
Deposited By: YURY YURYEV
Deposited On:20 Jun 2012 19:45
Last Modified:18 Jan 2018 17:37
All items in Spectrum are protected by copyright, with all rights reserved. The use of items is governed by Spectrum's terms of access.

Repository Staff Only: item control page

Downloads per month over past year

Research related to the current document (at the CORE website)
- Research related to the current document (at the CORE website)
Back to top Back to top