Statistical polymer segments

Since branched chains like LDPE have many chain ends, it is customary to use the radius of gyration, S, as a measure of the distribution of polymer segments. The radius of gyration is the distance of a chain end from the polymer s center of gravity rather than a measure of the RMS. Both measures are statistically related. 

Smith, Lemstra and Booij developed a similar argument for a gel-spun fibre. The molecular weight between entanglements in the undiluted polymer melt is denoted by M,. The number of statistical chain segments between entanglements is given by... 

Some important properties of polymer chains in dilute solutions [steric hindrance parameter, characteristic ratio, persistence length, radius of gyration, statistical chain segment length (introduced earlier, in Chapter 11), intrinsic viscosity, and viscosity at small but finite concentrations] will be discussed, and new correlations will be presented for the steric hindrance parameter and the molar stiffness function, in Chapter 12. 

Several parameters, most of which are interrelated and can be estimated in terms of each other, are utilized to describe the conformational properties of polymer chains [1,2]. These quantities include the steric hindrance parameter a, the characteristic ratio Cx, the persistence length Ip, the statistical chain segment (or Kuhn segment) length lk, the root mean square radius of gyration Rg (often briefly referred to as simply the "radius of gyration"), and the molar... 

Table 12.1. Literature data for the statistical chain segment length lk, in units of A, tabulated by Bershtein and Yegorov [18], The average value is listed below for any polymer for which more than one lk value or a range of lk values was indicated.

Methods for analysing the polarizability and nonlinear optical response of polymers that can be broken into statistically oriented segments or into active chromophores distributed on a backbone have been described by Pretre et al,216 Nanavati et al.217 and Dworczak et a/.218... 

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