writer：Niu YH, Wang ZG, Duan XL, Shao W, Wang DJ, Qiu J.
keywords：长链支化，共混物，热氧化，流变学
source：期刊
specific source：J. Appl. Polym. Sci. 2011, 119, 530-538.
Issue time：2011年

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 eta*. 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.