SYNTHESIS, CHARACTERIZATION AND MECHANICAL-PROPERTIES OF NETWORKS PREPARED FROM POLY(PROPYLENE GLYCOL) DI(ETHYLMALEATE) AND A TRIFUNCTIONALTHIOL

One option to understand and possibly improve the properties of thermo sets is to investigate well-defined polymer networks. Various novel, a lpha, omega-ethylmaleate functionalized poly(propylene glycol)s were e ndlinked with a trifunctional thiol, 2-ethyl-2-(hydroxymethyl)-1,3-pro panediol tris(3-mercaptopropionate) (EHPT). Model reactions of EHPT an d diethyl maleate indicated that a substitution effect in the thiol is absent. Characterization of the model networks revealed that the mole cular weight between junction points, M(c), calculated from the sol fr action (branching theory) agrees with the M(c) calculated from the ten sile storage rubber modulus E'. The glass transition temperature (T-g) decreases linearly with increasing M(c). The K-1c (critical stress in tensity factor) seems to be independent of the crosslink density. Copy right (C) 1996 Elsevier Science Ltd.