Polymerhyphen;Melt Viscosity and the Glass Transition: An Evaluation of the Adamndash;Gibbs and the Freehyphen;Volume Models

摘要

The Adamndash;Gibbs and the freehyphen;volume theories of polymerhyphen;melt viscosity and the glass transition are applied to the infinite polymethylene chain by comparing the exponential terms in the respective viscosity equations:2.3Bthinsp;sol;thinsp;lpar;Tthinsp;minus;thinsp;T0rpar;thinsp;equals;thinsp;Cthinsp;sol;thinsp;TScthinsp;equals;thinsp;bthinsp;sol;thinsp;phgr;. It is shown that the configurational entropyScand the free volumephgr;, which apply in these equations, constitute only a portion of the thermodynamic ldquo;excessrdquo; liquid entropy and volume. In an alternate form of the Andash;G equation:Cthinsp;sol;thinsp;TScthinsp;equals;thinsp;Dgr;mgr;z*thinsp;sol;thinsp;RT, ifDgr;mgr;is identified as2.3BR, zg*turns out to be equal to the ldquo;activation volumerdquo; expressed as monomer segments atTg. In the Adamndash;Gibbs context, the glass transition is assumed to be characterized by the constant:zg*Scgthinsp;equals;thinsp;5.5e.u.On this basis, a value ofScis derived for polystyrene atTmwhich agrees with independent estimates. Values of the Andash;G and the freehyphen;volume parameters are reported for (CH2)infin;, polystyrene, and polyisobutylene, and relationships betweenScandphgr;are presented.