Amorphous copolyesters based on bibenzoic acids and neopentyl glycol. Issue 5 (23rd December 2018)

• Record Type: Journal Article
• Authors: Eliot Edling, Hans; Mondschein, Ryan J.; Davis, Mark K.; Long, Timothy E.; Richard Turner, Sam
• Is Part Of: Journal of polymer science. Volume 57:Issue 5(2019)
• Page Start: 579
• Page End: 587
• Publication Date: 2018-12-23
• Subjects: amorphous -- bibenzoate -- calorimetry -- cyclohexanedimethanol -- neopentyl glycol -- polyester -- rheology; 547
• DOI: 10.1002/pola.29296
• Languages: English
• ISSNs: 0887-624X

Abstract

ABSTRACT: High T g amorphous copolyester thermoplastics were synthesized by incorporating 4, 4′‐bibenzoate (4, 4′BB) and 3, 4′‐bibenzoate moieties into the polyester backbone via melt polycondensation. The high levels of crystallinity typically associated with 4, 4′BB containing polyesters were suppressed through copolymerization of ethylene glycol, 1, 4‐cyclohexane dimethanol, and neopentyl glycol (NPG) diols. NPG was shown to be highly effective in suppressing crystallization and was used to produce amorphous compositions with T g 's as high as 129 °C. Diol ratios were determined by 1 H NMR spectroscopy and molecular weights were assessed with inherent viscosity ( η inh ). Thermogravimetric analysis showed single‐step weight losses in the range of 395– 419 °C. Differential scanning calorimetry was used to determine melting points and glass transition temperatures over a wide range of copolyester compositions and identified amorphous compositions. Dynamic mechanical analysis confirmed T g 's and was used to study β ‐relaxations below the T g . Rheological analysis revealed the effect of NPG structures on shear thinning and thermal stability. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem.2019, 57, 579–587 Abstract : Novel copolyesters were synthesized containing bibenzoate structures and various diols by using melt polycondensation. Neopentyl glycol, ethylene glycol, and 1, 4‐cyclohexanedimethanol were investigated for their ability to suppress crystallinity in copolyesters and produce amorphous materials. Amorphous copolyesters with glass transition temperatures as high as 129 °C were shown to have good melt stability and favorable mechanical properties relative to other amorphous copolyesters.