Dilute solution properties of polylaurolactam

For a number of fractions and unfractionated samples of polylaurolactam, molecular weights ($\text{M}{}_{\mathrm{<mtext>w</mtext>}}\text{= 1 × 10}{}^4\text{?12·5 × 10}{}^4$) were measured by the light-scattering method in a mixed solvent of m-cresol with 60 vol. % 2,2,3,3-tetrafluoropropanol; intrinsic viscosities were determined in m-cresol and 96% H₂SO₄, and the constants of the Mark-Houwink equation were calculated. The calculated values of the characteristic ratio of unperturbed dimensions (virtually identical for m-cresol and 96% H₂SO₄) were compared with the respective values for polypyrrolidone and polycaprolactam. It was found that the higher frequency of the CONH-groups reduces the rigidity of the polyamide chain.