CONTRIBUTION OF ENTANGLEMENTS TO THE MODULUS OF END-LINKED POLY(ETHYLENE OXIDE) NETWORKS

Poly(ethylene oxide) networks were made at 75-degrees-C by end-linking of short linear chains with an excess of Tolonate HDT, a tri-function al aliphatic isocyanate.Molecular weights of poly(ethylene oxide)were 4000, 6000 and 12000. The observed elastic moduli were much higher tha n predicted from affine theory, indicating a large contribution from e ntanglements in contrast to the findings of previous studies. With inc reasing excess of cross-linker, the contribution from entanglements le vels off at a value of approximately 5 MPa which is in good agreement with the rubber plateau modulus of pure poly(ethylene oxide).