The radius of gyration is a good parameter for characterizing the dimensional distribution of a given polymer chain at perturbation conditions.But it is hard to give information about stack structures of polymer chains both in bulk and solution.It is highly desirable to establish the relationship between the micro structure parameter and macroscopical properties of polymers in bulk or in solution.The degree of chain overlap is a good parameter for that

which has been defined and applied very well in bulk state.Based on Flory theory of intrinsic viscosity of polymers and the model of concentration dependence of polymer chain dimension in solution

a quantitative expression of the degree of chain overlap ξc

ξc≡c/ρc=4πNA/3Φ′×［η］c/{1+［η］-［η］θ/［η］θ［1-exp(-c /c*)］}

in terms of the concentration of the polymer solution from diluted solution to concentrated solution was deduced.A master curve of the relative viscosity ηr of polychloroprene solutions in literature for different molecular weights

various solvents and temperatures can be obtained as the ξc was used as a variable for replacing the concentration.It suggests that the microstructure parameter of ξc and its quantitative expression proposed in solution state could correlate the macroscopical properties of polymer solutions，ηr，very well even at high concentration range.Also，ξc could be expected to be a promising micro-structure parameter for associating other properties of polymer in solutions.