Diluent induced cyclization and phase separation in polymer networks

0366161 - ÚMCH 2012 RIV DE eng J - Journal Article
Dušková-Smrčková, Miroslava - Valentová, H. - Ďuračková, Andrea - Dušek, Karel
Diluent induced cyclization and phase separation in polymer networks.
Macromolecular Symposia. 306-307, č. 1 (2011), s. 67-76. ISSN 1022-1360.
[Polymer Networks Group Meeting /20./. Goslar, 29.08.2010-02.09.2010]
R&D Projects: GA ČR GA106/08/1409
Institutional research plan: CEZ:AV0Z40500505
Keywords : cyclization * elasticity * gelation
Subject RIV: JI - Composite Materials

The effect of the presence of diluent during network formation on the gel-point conversion, αcrit, and on the equilibrium elastic modulus was studied using polyurethane networks from star-shaped polyols and a star-shaped triisocyanate.The dependence of αcrit on reciprocal concentration of functional groups,1/c0, extrapolated well for 1/c0—›0 to the value calculated corresponding to the ring-free system.The decrease of the equilibrium modulus and the concentration of elastically active network chains (EANC) in dependence on the volume fraction of polymerizable compounds (solids).The continuous change of gel volume as a result of phase separation was obtained by solving an integral equation respecting the thermodynamic stability of the system.The change of the concentration of EANCs obtained from equilibrium modulus was translated into the intermolecular conversion calculated using the branching theory. Intermolecular conversion depended linearly on the shift of the gel-point conversion.
Permanent Link: http://hdl.handle.net/11104/0201235