Thermal analysis, glass transition temperature and rheological behaviour of emulsion copolymers of methyl methacrylate with styrene

✍ Scribed by Liucheng Zhang; Guodong Liu; Rongqin Ji; Yanmei Yao; Xiongwei Qu; Liting Yang; Jungang Gao

• Book ID: 104526564
• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 129 KB
• Volume: 52
• Category: Article
• ISSN: 0959-8103
• DOI: 10.1002/pi.1014

✦ Synopsis

Abstract

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