Modern Characterization of Long-Chain Branching

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Abstract
The importance of branching degree and its distribution in a polymer has been broadly recognized in polymer processing. Characterization with GPC-LALLS is becoming popular in the industry currently due to its instrumental and theoretical development. A recently published computer simulation supports strongly the hypothesis that the momentarily eluted polymer is essentially monodisperse on molecular weight distribution even in case of a real GPC. The relationship between intrinsic viscosity [η] and branching degree is not comprehensively understood although it is most fundamental in any approach to the branching structure with GPC. Therefore, the semiempirical exponential relationship between [η] and another property well correlated to the branching degree is investigated. The mean square radius of gyration is representative of such properties. Anyway, the exponent should be determined by the experiments using model polymers with known branching degrees. The relationships between [η] and the Stokes radius or the second virial coefficient are also studied but their completeness is less satisfactory. The modern renormalization group method makes a great success of the quantitative treatment of chain conformation of branched polymers of various kinds in good solvents, although the solution for the randomly branched polymers in most industrial applications is not yet given.