Viscosity‐molecular weight relation and unperturbed dimensions of polyethylene terephthalate

A series of polyethylene terephthalate resins were characterized for molecular weight by light scattering measurements in trifluoracetic acid (TFA) solution and for intrinsic viscosity in TFA and in a mixture of tetrachloroethane (TCE)/phenol. The following viscositymolecular weight relations were established: The unperturbed dimensions (〈r02〉/M)1/2 were derived by the method of KURATA‐STOCK‐MAYER (0.985 a. u.) and STOCKMAYER‐FIXMAN (0.966 a.u.). The steric factor (1.4) is similar to that of other polymers with p‐phenylene groups in their chain backbone. The results are compared to previous findings based on end group, osmometric, and cryoscopic data.