Blends of poly(ethylene terephthalate) and cellulose

Poly(ethylene terephthalate) (PET) (intrinsic viscosity 0.59) and cellulose (Whatman) are compatible in up to 7.5% (w/v) solutions in trifluoroacetic acid and in mixtures of trifluoroacetic acid and methylene chloride. Evaporation of the solutions yielded films that did not contain cellulose per se , but rather partial esters of cellulose and trifluoroacetic acid. Clear films were cast from these solutions with compositions of 100/0, 75/25, 50/50, 25/75, and 0/100 PET. cellulose (w/w). Infrared spectra and DSC measurements indicate specific polymer‐polymer interaction although two T g were observed. Hydrolysis of the trifluoroacetate films to blends of PET and regenerated cellulose was accomplished by suspending the films in water at the boil. Infrared spectra indicate no interaction between the two polymers, although the films of the 50/50 and 25/75 PET. cellulose compositions were clear. The 25/75 composition, from its T g and melting‐point behavior appears to be a dispersion of very small‐particle PET in a cellulose matrix. The 75/25 composition became opalescent during the hydrolysis and may be a dispersion of large‐particle cellulose in a PET matrix. The regenerated cellulose appears to be a mixture of cellulose II and IV polymorphs.