Translational diffusion coefficient and diffusion average molar mass of polydisperse polymers in solution

✍ Scribed by G. Vancso

• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 293 KB
• Volume: 26
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(90)90252-y

✦ Synopsis

Results of photon correlation spectroscopy measurements on mixtures of two polystyrene standards in dilute cyclohexane solutions are reported. The centre of mass translational diffusion coefficients (DC) of bimodal mixtures with various weight compositions and of the two components were determined. For the mixtures, the magnitude of the average DC was also calculated assuming that the corresponding value is a z-average over the molar mass distribution function. Calculated and measured values for three mixtures agree within the 1% experimental error. The diffusion average molar mass ~o, which describes the molar mass dependence of the DC in polydisperse systems, was calculated for different molar mass distribution functions. The results show that the value of ~o falls between the weight and z-average molar masses, 2f/ w and 20"~. The relative position of ~Oi~ over the molar mass scale with respect to Mw and 2~: is calculated as a function of the polydispersity index Mw/A3s for three different distributions.