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Thermal analysis, glass transition temperature and rheological behaviour of emulsion copolymers of methyl methacrylate with styrene
Author(s) -
Zhang Liucheng,
Liu Guodong,
Ji Rongqin,
Yao Yanmei,
Qu Xiongwei,
Yang Liting,
Gao Jungang
Publication year - 2003
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.1014
Subject(s) - copolymer , glass transition , polymer chemistry , methyl methacrylate , materials science , differential scanning calorimetry , rheology , monomer , thermogravimetric analysis , styrene , thermodynamics , polymer , chemistry , composite material , organic chemistry , physics
Poly(MMA‐ ran ‐St) samples were synthesized under monomer‐starved conditions (drop feeding method) by emulsion copolymerization. Their thermostability was determined by thermogravimetric analysis. The glass transition temperature ( T g ) of the copolymers was determined by differential scanning calorimetry (DSC) and torsional braid analysis (TBA). The results showed that the MMA–St copolymers exhibit an asymmetric T g versus composition curve, which could not be interpreted by Johnston's equation, taking the different contributions of the diads to the T g of the copolymer into consideration. A new sequence distribution equation taking into account the different contributions of the triads was proposed to predict the copolymer T g . The new equation fitted the experimental data exactly. The T g determined by torsional braid analysis (TBA) is higher than the one determined by DSC, but the difference is not constant. The rheological behaviour of the copolymers was also studied and T gTBA ‐ T gDSC increased with the increasing flow index of the copolymer. © 2003 Society of Chemical Industry