Thermal oxidation‐induced long chain branching and its effect on phase separation kinetics of a polyethylene blend |
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Authors: | Yan‐Hua Niu Zhi‐Gang Wang Xiao‐Li Duan Wei Shao Du‐Jin Wang Jie Qiu |
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Affiliation: | 1. CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui Province 230026 People's Republic of China;2. CAS Key Laboratory of Engineering Plastics, Joint Laboratory of Polymer Science and Materials, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190 People's Republic of China;3. Graduate School, Chinese Academy of Sciences, Beijing, 100049 People's Republic of China |
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Abstract: | Thermal oxidation‐induced long chain branching (LCB) during the molding processes for polyolefin copolymer poly(ethylene‐co‐butene) (PEB) and its blend with another polyolefin copolymer poly(ethylene‐co‐hexene) (PEH/PEB 50/50 blend, denoted as H50) was investigated mainly by rheological measurements. LCB with different levels could be introduced on PEB backbones by changing the molding temperature and/or molding time, which could be sensitively characterized by changes of rheological parameters, that is, storage modulus G′ and complex viscosity η*. Thermal oxidation‐induced LCB of PEB in H50 samples could largely influence the phase separation kinetics. Rheological measurements and phase‐contrast optical microscope observations coherently indicated that thermal oxidation‐induced LCB of PEB more or less retarded the development of phase separation and once it reached a certain level, the reduced chain diffusion even arrested phase separation. The decrease of mass‐averaged molecular mass in H50 with high LCB level was ascribed to the reduced hydrodynamic volume. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 |
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Keywords: | polyolefin blend long chain branching phase separation kinetics |
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