Rheology and Crystallization of Long-Chain Branched Poly(l‑lactide)s with Controlled Branch Length

A series of long-chain branched poly(l-lactide)s (LCB-PLAs) with controlled branch length were prepared by a simple and efficient method through a combination of ring-opening polymerization (ROP) of l-lactide and a coupling reaction between the terminal OH groups of the PLA prepolymers and the NCO g...

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Bibliographic Details
Published in:Industrial & engineering chemistry research 2012-08, Vol.51 (33), p.10731-10741
Main Authors: Wang, Liangyan, Jing, Xiabin, Cheng, Haibo, Hu, Xiuli, Yang, Lixin, Huang, Yubin
Format: Article
Language:English
Subjects:
Applied sciences
Branched
Chemical engineering
Crystallization
Crystallization, leaching, miscellaneous separations
Density
Exact sciences and technology
Molecular structure
Polymerization
Prepolymers
Rheology
Viscosity
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Summary:A series of long-chain branched poly(l-lactide)s (LCB-PLAs) with controlled branch length were prepared by a simple and efficient method through a combination of ring-opening polymerization (ROP) of l-lactide and a coupling reaction between the terminal OH groups of the PLA prepolymers and the NCO groups of HDI. The influences of reaction conditions on the synthesis of the LCB-PLAs were investigated, and the structures of the resultant LCB-PLAs were characterized by 1H NMR spectroscopy and SEC-MALLS. By adjusting the degree of polymerization and the composition of the prepolymers, LCB-PLAs with different branch densities and molecular weights between branch points were obtained. The effect of macromolecular chain branching on the rheology and crystallization of PLA was also investigated. The LCB structure contributed to the enhancement of the zero-shear viscosity, complex viscosity, storage modulus, melt strength, and strain hardening under elongational flow. Thermal behavior indicated that the branch structure resulted in a short nucleation induction period and more rapid crystallization, which can be a guarantee of high-strength foams.
ISSN:0888-5885
1520-5045
DOI:10.1021/ie300524j