A method is described for simulating the dynamical behavior of a linear polymer in dilute solution, subject to random collision with solvent molecules. Equilibrium distributions of various chain dimensions may be obtained by periodic inspection of the chain. Relaxation phenomena in such chains may also be studied. Results are given for equilibrium distribution and relaxation behavior of the end-to-end length, for chains of 8, 16, 32, and 64 beads. The equilibrium chain dimensions are in satisfactory accord with the calculations of Wall and his collaborators, while the relaxation times are close to those predicted with the aid of the hydrodynamic theory of Rouse and Zimm.

A method is presented for obtaining correlation functions in the free-draining statistical-bead model (Rouse model) of a polymer chain. Autocorrelation functions for the squares of end-to-end length and radius of gyration are given as functions of the number of statistical segments in the chain.

Linear polyeth yle ne Sta ndard Refe re nce Mate ri a ls S RM 1482, 1483 , a nd 1484 a re certifie d for we ightaverage mo lecular we ight Mw. In thi s pa pe r th e experime nt a l proced ures em ployed for th e d e te rmin a ti on of Mw for th ese ma te ri a ls by li ght scatt e ring a re d escribed, and th e tec hniqu es used to a na lyze th e da ta a nd to estima te limit s of syste mati c e rro r a re d iscussed .Key wo rds: F racti on; li ght scatt e rin g; limiting viscosit) nu mber; na rrow molecul a r we ight d is tribution; Ilumberaverage mo lecula r we ight ; polyeth yle n e; Sta nda rd Refe rence Ma te ri a l; we ight-average mo lecular we ight.

The conformations of random-coil polymer chains are known to be appreciably more aspherical than might have been expected intuitively. However, this instantaneous asphericity will only affect the measured physical properties of flexible chains in solution if the relaxation of the asphericity requires a time longer than the inherent sampling time of the experiment. It is therefore important, in the analysis of phenomena which depend upon chain shape, to know the time scale over which deviations from spherical symmetry persist. In this paper we extend our previous work on the relaxation of asphericity in chains without excluded volume interactions and present corresponding results for chains with excluded volume. Autocorrelation functions for the radius of gyration squared, its principal components, and the moments of inertia are determined using a dynamical model for linear polymer chains which simulates excluded volume effects. The results suggest that the asphericity of a random-flight chain is increased by the introduction of excluded volume interactions, and that the segment distribution will appear spherically symmetric only when it is averaged over a time comparable with or longer than the longest times in the relaxation-time spectrum of the chain.

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