The 1H NMR spectrum of Mater-Bi (Fig. 3) further confirms the
structural information obtained by FT-IR spectral data. The ratio
between each monomer (butylene terephthalate and butylene adipate)
has been determined from the 1H NMR spectra. The integration
of the adequate peaks of the butylene adipate unit at 2.33 ppm
and of the butylene terephthalate unit at 8.1 ppm (aromatic) gives
the composition of 51.3 mol% of butylene terephthalate and 48.7%
of butylene adipate [21,34].