Long chain branching effects prediction

However, without theories that explicitly consider the effect of long-chain branching on rheology, we can say nothing beyond affirming that the samples contain LCB. In what follows, we will describe some recently developed theories for predicting the linear viscoelasticity of long-chain-branched polymer melts. Theories for the nonlinear viscoelasticity of branched polymers are covered in Section 11.6. 

Meyer and Spitzer (52) have calculated the electronic properties of rings and chains of sulfur atoms. An EH procedure was employed with parameters chosen to fit the energy levels of S8. For S4 it was found that the tetrahedron was only weakly stable, with branched chains and zigzag chains more stable. The calculations predict that above S5 the gas-phase species are cyclic. In addition to these geometry effects, a long-wavelength shift was observed for light absorption by the chains. 

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