摘要：

Part I. The experimental molecular dimensions for polymers obtained by direct averaging over a large number of chains offers experimental proof of the validity of the expressions for and < r squared >, where this expression is the mean square end-to-end distance of the chain, based on worm-like statistics. The values of are assumed to be correct based on the behavior of but the values of <1/r squared> are considered as approximations due to an error of < 20 percent in the averaging process for . An expression is given which corrects the to the theoretical value while the <1/r squared> correction is estimated graphically. Part II. Cellulose trinitrate in n-butyl acetate was shown to approach rod-like behavior at low molecular weights and to become more flexible as the molecular weight increased from considerations based on both viscosity and sedimentation. The approximate points at which the transitions to rod-like and Gaussian behaviors occur could only be estimated as less than 100,000 and greater than 500,000, respectively, although these are in range of the transition points found for cellulose trinitrate in other solvents. The dimensions calculated for the rod-like model are generally in poor agreement with the dimensions calculated from the Kurata-Stockmayer Theory.

展开