Miscibility and transesterification in blends of liquid crystalline copolyesters and polyarylate

✍ Scribed by Horng-Long Tyan; Kung-Hwa Wei

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 458 KB
• Volume: 36
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(199808)36:11<1959::aid-polb17>3.0.co;2-6

✦ Synopsis

Blends of poly(oxybenzoate-p-ethylene terephthalate) (POB-PET) and polyarylate were confirmed to be a partially miscible system by differential scanning calorimetry. When 60/40 POB-PET/PAr blend was annealed at high temperature (above 270ЊC) for several minutes, the ester-ester interchange (transesterification) in the blend took place immediately, as evidenced by Fourier Transformed infrared analyses. The analysis of the blend annealed at 290ЊC by 1 H-13 C nuclear magnetic resonance disclosed that there were four new diads appearing in 15 min and an additional one produced in 60 min during the heat treatment. The miscibility between POB-PET and polyarylate increased with the mol concentration of these new diads judging from differential scanning calorimetry. The evolution of the concentration of the diad ethylene glycol-isophthalate during the annealing can be described by a second-order reaction. The activation energy of forming the diad ethylene glycol-isophthalate was 26.5 kcal/mol, and the preexponential factor for the transesterification reaction is 3.7 1 10 8 min 01 .