摘要 : More than fifty years ago, Zimm and Stockmayer calculated the average contraction factor of star-branched polymers (stars) with uniformly distributed arms to be 6fl{(f + 1)(f + 2)}. Since then this contraction factor has also been... 展开 More than fifty years ago, Zimm and Stockmayer calculated the average contraction factor of star-branched polymers (stars) with uniformly distributed arms to be 6fl{(f + 1)(f + 2)}. Since then this contraction factor has also been used for stars with other arm distributions. In this paper we determine the (probability) density function of the contraction factor of stars with arms with a Flory (most probable) distribution and conclude that this function is equal to that for stars with uniformly distributed arms. Other arm distributions, however, lead to different contraction factor density functions. The moment of the contraction factor distribution were precisely determined with the aid of a recursion method. The stochastical behavior of the contraction factor of stars was applied to size-exclusion chromatography (SEC) analysis and showed that upward correction of the crude SEC data is necessary to determine the proper molecular-mass distribution of stars. [References: 36] 收起