Studies on amylose and its derivatives. X. Dilute solution conformation of amylose tripropionate

Some dilute solution parameters have been measured for linear amylose tripropionate samples in ethyl acetate and tetrahydrofuran. Mark-Houwink relations for the molecular weight range 10⁴ to 1.5 × 10⁵ have been established, and the exponents are 0.58 and 0.61 in ethyl acetate and tetrahydrofuran, respectively. This indicates that the coil is only slightly expanded in these solvents. A value of 6.21 was calculated for the characteristic ratio C_∞ leading to a steric parameter of σ = 2.32. The temperature dependence of the unperturbed dimensions (d In C_∞/dT) was found to negative and of the order ?4.05 × 10^?3°K^?1.