Quenching enthalpy/entropy

Blundell [28] first demonstrated that the main features of crystallization for thermotropic longitudinal PLCs are (1) small crystallites ( 5 nm for quenched samples and about 10 nm across for annealed ones) (2) limited crystallinity (about 20% in wide angle X-ray diffraction (WAXD)) (3) low surface energy of the crystallites (4) little change of molecular conformation before and after melting and (5) low fusion entropy and enthalpy (sometimes no detectable endotherm on DSC thermograms). A model of small crystal size for extended chain polymers was proposed by Blundell [28]. 

Separation of the two stages of polymerization is possible because the propagation of strained monomers is much faster than the backbiting and chain transfer. In contrast to the entropy-driven polymerizations of unstrained cydosiloxanes, the driving force for the polymerization of cydotrisiloxanes is the enthalpy of the ring-strain release. If the polymerization is quenched at a proper moment, a high yield of polymer maybe obtained even in the case when the equilibrium concentration of linear polysiloxane is very low. 

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