PET copolyesters made from a D-mannitol-derived bicyclic diol

The carbohydrate-based bicyclic diol 2,4: 3,5-di-O-methylene-D-mannitol (Manx) was made to react in the melt with ethylene glycol and dimethyl terephthalate to produce random PE(x)Manx(y)T copolyesters covering the whole range of molar compositions. The copolyesters had weight-average molecular weights in the 33 000-41 000 g mol(-1) interval and were thermally stable up to nearly 380 degrees C. They displayed T-g in the 81 to 137 degrees C range with values largely increasing with the content in Manx units. Copolyesters containing minor amounts of Manx were semicrystalline whereas those with contents equal to or more than 30% of Manx were amorphous. Stress-strain parameters were affected by composition, increasing tensile strength and elastic modulus and reducing elongation at break when introducing Manx units. These bio-based PET copolyesters showed enhanced susceptibility to hydrolysis.