Steady-State Compliance of Model Star Polymers

2 Steady-State Compliance of Model Star Polymers 

For multi-armed stars, where is less than M, Ham s model for unentangled melts [85] indicates that the ratio of /° values for /-armed stars and linear molecules having the same molecular weight, is given by  

Combining this with the prediction of the Rouse-Bueche theory for Hnear, imentangled melts (Eq. 6.16), we obtain  

GeU etal. [95] fotmd that the steady-state compliance of a symmetric, three-arm star with Mg/Mg = 18 was about 18 -10 cm /dyn, whereas the value predicted by Eq. 5.47 is about 14 10 cm /dyn (g2 = 0.63 for/= 3). At the same time, the value normally expected for an entangled, monodisperse, linear polymer, as given by Eq. 5.10, is much less than 18 -10 cm / dyn. 

We see here once again that the behavior of the branched polymer with entangled arms is much closer to that of an unentangled branched polymer than to an entangled linear polymer. 

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