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Rheological and topological characterizations of electron beam irradiation prepared long‐chain branched polylactic acid
Author(s) -
Wang Yongbin,
Yang Liang,
Niu Yanhua,
Wang Zhigang,
Zhang Jun,
Yu Fengyuan,
Zhang Hongbin
Publication year - 2011
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.34276
Subject(s) - tmpta , materials science , radius of gyration , branching (polymer chemistry) , rheology , polymer chemistry , irradiation , crystallinity , viscometer , chemical engineering , composite material , monomer , viscosity , polymer , acrylate , nuclear physics , physics , engineering
In this study, a series of linear‐ and long‐chain branched polylactic acid (PLA) samples was prepared by electron beam irradiation without or with addition of a trifunctional monomer, trimethylolpropane triacrylate (TMPTA). The chain structures of the PLA samples were characterized by size‐exclusion chromatography coupled with a light scattering detector (SEC‐MALLS) and shear and extensional rheology. PLA tends to degrade while keeps linear structures with increasing irradiation dose and without addition of TMPTA, as evidenced by decreased molecular mass M w and reductions of storage modulus G′ and the zero shear viscosity η 0 . Long‐chain branched PLA samples were successfully prepared with irradiation and addition of TMPTA, which shows prominent higher η 0 and apparent flow activation energy, longer characteristic relaxation time τ, and pronounced strain‐hardening behaviors. With increasing amount of TMPTA, M w dependences of η 0 and the root mean square radius of gyration R g obviously deviate from the scaling relation of linear PLA samples, which strongly indicates the increased long‐chain branching degree for the branched PLA samples. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011