Temperature-dependence modeling of highly crosslinked polymer networks

Abstract

The dependence on the temperature of the state of a highly crosslinked polymer network can be modeled as a function of well-defined molecular-level network parameters to yield a simple applied model equation. The tightness and strength (modulus of elasticity) of the crosslinked networks formed, as well as any further tightening of the network due to further curing, can easily be compared with the parameters A, M, and α (the coefficient of branching) and the m/E ratio and, therefore, with parameters directly related to molecular-level characteristics of the system. The crosslinking contribution to the network is represented by A and M, the former representing the frequency of crosslinking and the latter having the dimensions of an energy. The ratio m/E, that is, the ratio of the average number of degrees of freedom of chain segments between crosslinking nodes (m) to the average energy of nonbonded atom interactions between the same segments (E), and α model the noncrosslinked contribution to the characteristics of the network. These are the same parameters that appear in the simple equation modeling the dependence of the characteristics of the network on the temperature within a limited temperature range. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2416–2426, 2003